Spring Cloud provides tools for developers to quickly build some of the common patterns in distributed systems (e.g. configuration management, service discovery, circuit breakers, intelligent routing, micro-proxy, control bus, one-time tokens, global locks, leadership election, distributed sessions, cluster state). Coordination of distributed systems leads to boiler plate patterns, and using Spring Cloud developers can quickly stand up services and applications that implement those patterns. They will work well in any distributed environment, including the developer’s own laptop, bare metal data centres, and managed platforms such as Cloud Foundry.
Version: Camden.SR7
Features
Spring Cloud focuses on providing good out of box experience for typical use cases and extensibility mechanism to cover others.
-
Distributed/versioned configuration
-
Service registration and discovery
-
Routing
-
Service-to-service calls
-
Load balancing
-
Circuit Breakers
-
Global locks
-
Leadership election and cluster state
-
Distributed messaging
Cloud Native Applications
Cloud Native is a style of application development that encourages easy adoption of best practices in the areas of continuous delivery and value-driven development. A related discipline is that of building 12-factor Apps in which development practices are aligned with delivery and operations goals, for instance by using declarative programming and management and monitoring. Spring Cloud facilitates these styles of development in a number of specific ways and the starting point is a set of features that all components in a distributed system either need or need easy access to when required.
Many of those features are covered by Spring Boot, which we build on in Spring Cloud. Some more are delivered by Spring Cloud as two libraries: Spring Cloud Context and Spring Cloud Commons. Spring Cloud Context provides utilities and special services for the ApplicationContext
of a Spring Cloud application (bootstrap context, encryption, refresh scope and environment endpoints). Spring Cloud Commons is a set of abstractions and common classes used in different Spring Cloud implementations (eg. Spring Cloud Netflix vs. Spring Cloud Consul).
If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:
Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).
Note
|
Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. |
Spring Cloud Context: Application Context Services
Spring Boot has an opinionated view of how to build an application with Spring: for instance it has conventional locations for common configuration file, and endpoints for common management and monitoring tasks. Spring Cloud builds on top of that and adds a few features that probably all components in a system would use or occasionally need.
The Bootstrap Application Context
A Spring Cloud application operates by creating a "bootstrap"
context, which is a parent context for the main application. Out of
the box it is responsible for loading configuration properties from
the external sources, and also decrypting properties in the local
external configuration files. The two contexts share an Environment
which is the source of external properties for any Spring
application. Bootstrap properties are added with high precedence, so
they cannot be overridden by local configuration, by default.
The bootstrap context uses a different convention for locating
external configuration than the main application context, so instead
of application.yml
(or .properties
) you use bootstrap.yml
,
keeping the external configuration for bootstrap and main context
nicely separate. Example:
spring: application: name: foo cloud: config: uri: ${SPRING_CONFIG_URI:http://localhost:8888}
It is a good idea to set the spring.application.name
(in
bootstrap.yml
or application.yml
) if your application needs any
application-specific configuration from the server.
You can disable the bootstrap process completely by setting
spring.cloud.bootstrap.enabled=false
(e.g. in System properties).
Application Context Hierarchies
If you build an application context from SpringApplication
or
SpringApplicationBuilder
, then the Bootstrap context is added as a
parent to that context. It is a feature of Spring that child contexts
inherit property sources and profiles from their parent, so the "main"
application context will contain additional property sources, compared
to building the same context without Spring Cloud Config. The
additional property sources are:
-
"bootstrap": an optional
CompositePropertySource
appears with high priority if anyPropertySourceLocators
are found in the Bootstrap context, and they have non-empty properties. An example would be properties from the Spring Cloud Config Server. See below for instructions on how to customize the contents of this property source. -
"applicationConfig: [classpath:bootstrap.yml]" (and friends if Spring profiles are active). If you have a
bootstrap.yml
(or properties) then those properties are used to configure the Bootstrap context, and then they get added to the child context when its parent is set. They have lower precedence than theapplication.yml
(or properties) and any other property sources that are added to the child as a normal part of the process of creating a Spring Boot application. See below for instructions on how to customize the contents of these property sources.
Because of the ordering rules of property sources the "bootstrap"
entries take precedence, but note that these do not contain any data
from bootstrap.yml
, which has very low precedence, but can be used
to set defaults.
You can extend the context hierarchy by simply setting the parent
context of any ApplicationContext
you create, e.g. using its own
interface, or with the SpringApplicationBuilder
convenience methods
(parent()
, child()
and sibling()
). The bootstrap context will be
the parent of the most senior ancestor that you create yourself.
Every context in the hierarchy will have its own "bootstrap" property
source (possibly empty) to avoid promoting values inadvertently from
parents down to their descendants. Every context in the hierarchy can
also (in principle) have a different spring.application.name
and
hence a different remote property source if there is a Config
Server. Normal Spring application context behaviour rules apply to
property resolution: properties from a child context override those in
the parent, by name and also by property source name (if the child has
a property source with the same name as the parent, the one from the
parent is not included in the child).
Note that the SpringApplicationBuilder
allows you to share an
Environment
amongst the whole hierarchy, but that is not the
default. Thus, sibling contexts in particular do not need to have the
same profiles or property sources, even though they will share common
things with their parent.
Changing the Location of Bootstrap Properties
The bootstrap.yml
(or .properties
) location can be specified using
spring.cloud.bootstrap.name
(default "bootstrap") or
spring.cloud.bootstrap.location
(default empty), e.g. in System
properties. Those properties behave like the spring.config.*
variants with the same name, in fact they are used to set up the
bootstrap ApplicationContext
by setting those properties in its
Environment
. If there is an active profile (from
spring.profiles.active
or through the Environment
API in the
context you are building) then properties in that profile will be
loaded as well, just like in a regular Spring Boot app, e.g. from
bootstrap-development.properties
for a "development" profile.
Overriding the Values of Remote Properties
The property sources that are added to you application by the
bootstrap context are often "remote" (e.g. from a Config Server), and
by default they cannot be overridden locally, except on the command
line. If you want to allow your applications to override the remote
properties with their own System properties or config files, the
remote property source has to grant it permission by setting
spring.cloud.config.allowOverride=true
(it doesn’t work to set this
locally). Once that flag is set there are some finer grained settings
to control the location of the remote properties in relation to System
properties and the application’s local configuration:
spring.cloud.config.overrideNone=true
to override with any local
property source, and
spring.cloud.config.overrideSystemProperties=false
if only System
properties and env vars should override the remote settings, but not
the local config files.
Customizing the Bootstrap Configuration
The bootstrap context can be trained to do anything you like by adding
entries to /META-INF/spring.factories
under the key
org.springframework.cloud.bootstrap.BootstrapConfiguration
. This is
a comma-separated list of Spring @Configuration
classes which will
be used to create the context. Any beans that you want to be available
to the main application context for autowiring can be created here,
and also there is a special contract for @Beans
of type
ApplicationContextInitializer
. Classes can be marked with an @Order
if you want to control the startup sequence (the default order is
"last").
Warning
|
Be careful when adding custom BootstrapConfiguration that the
classes you add are not @ComponentScanned by mistake into your
"main" application context, where they might not be needed.
Use a separate package name for boot configuration classes that is
not already covered by your @ComponentScan or @SpringBootApplication
annotated configuration classes.
|
The bootstrap process ends by injecting initializers into the main
SpringApplication
instance (i.e. the normal Spring Boot startup
sequence, whether it is running as a standalone app or deployed in an
application server). First a bootstrap context is created from the
classes found in spring.factories
and then all @Beans
of type
ApplicationContextInitializer
are added to the main
SpringApplication
before it is started.
Customizing the Bootstrap Property Sources
The default property source for external configuration added by the
bootstrap process is the Config Server, but you can add additional
sources by adding beans of type PropertySourceLocator
to the
bootstrap context (via spring.factories
). You could use this to
insert additional properties from a different server, or from a
database, for instance.
As an example, consider the following trivial custom locator:
@Configuration
public class CustomPropertySourceLocator implements PropertySourceLocator {
@Override
public PropertySource<?> locate(Environment environment) {
return new MapPropertySource("customProperty",
Collections.<String, Object>singletonMap("property.from.sample.custom.source", "worked as intended"));
}
}
The Environment
that is passed in is the one for the
ApplicationContext
about to be created, i.e. the one that we are
supplying additional property sources for. It will already have its
normal Spring Boot-provided property sources, so you can use those to
locate a property source specific to this Environment
(e.g. by
keying it on the spring.application.name
, as is done in the default
Config Server property source locator).
If you create a jar with this class in it and then add a
META-INF/spring.factories
containing:
org.springframework.cloud.bootstrap.BootstrapConfiguration=sample.custom.CustomPropertySourceLocator
then the "customProperty" PropertySource
will show up in any
application that includes that jar on its classpath.
Environment Changes
The application will listen for an EnvironmentChangedEvent
and react
to the change in a couple of standard ways (additional
ApplicationListeners
can be added as @Beans
by the user in the
normal way). When an EnvironmentChangedEvent
is observed it will
have a list of key values that have changed, and the application will
use those to:
-
Re-bind any
@ConfigurationProperties
beans in the context -
Set the logger levels for any properties in
logging.level.*
Note that the Config Client does not by default poll for changes in
the Environment
, and generally we would not recommend that approach
for detecting changes (although you could set it up with a
@Scheduled
annotation). If you have a scaled-out client application
then it is better to broadcast the EnvironmentChangedEvent
to all
the instances instead of having them polling for changes (e.g. using
the Spring Cloud
Bus).
The EnvironmentChangedEvent
covers a large class of refresh use
cases, as long as you can actually make a change to the Environment
and publish the event (those APIs are public and part of core
Spring). You can verify the changes are bound to
@ConfigurationProperties
beans by visiting the /configprops
endpoint (normal Spring Boot Actuator feature). For instance a
DataSource
can have its maxPoolSize
changed at runtime (the
default DataSource
created by Spring Boot is an
@ConfigurationProperties
bean) and grow capacity
dynamically. Re-binding @ConfigurationProperties
does not cover
another large class of use cases, where you need more control over the
refresh, and where you need a change to be atomic over the whole
ApplicationContext
. To address those concerns we have
@RefreshScope
.
Refresh Scope
A Spring @Bean
that is marked as @RefreshScope
will get special
treatment when there is a configuration change. This addresses the
problem of stateful beans that only get their configuration injected
when they are initialized. For instance if a DataSource
has open
connections when the database URL is changed via the Environment
, we
probably want the holders of those connections to be able to complete
what they are doing. Then the next time someone borrows a connection
from the pool he gets one with the new URL.
Refresh scope beans are lazy proxies that initialize when they are used (i.e. when a method is called), and the scope acts as a cache of initialized values. To force a bean to re-initialize on the next method call you just need to invalidate its cache entry.
The RefreshScope
is a bean in the context and it has a public method
refreshAll()
to refresh all beans in the scope by clearing the
target cache. There is also a refresh(String)
method to refresh an
individual bean by name. This functionality is exposed in the
/refresh
endpoint (over HTTP or JMX).
Note
|
@RefreshScope works (technically) on an @Configuration
class, but it might lead to surprising behaviour: e.g. it does not
mean that all the @Beans defined in that class are themselves
@RefreshScope . Specifically, anything that depends on those beans
cannot rely on them being updated when a refresh is initiated, unless
it is itself in @RefreshScope (in which it will be rebuilt on a
refresh and its dependencies re-injected, at which point they will be
re-initialized from the refreshed @Configuration ).
|
Encryption and Decryption
Spring Cloud has an Environment
pre-processor for decrypting
property values locally. It follows the same rules as the Config
Server, and has the same external configuration via encrypt.*
. Thus
you can use encrypted values in the form {cipher}*
and as long as
there is a valid key then they will be decrypted before the main
application context gets the Environment
. To use the encryption
features in an application you need to include Spring Security RSA in
your classpath (Maven co-ordinates
"org.springframework.security:spring-security-rsa") and you also need
the full strength JCE extensions in your JVM.
If you are getting an exception due to "Illegal key size" and you are using Sun’s JDK, you need to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files. See the following links for more information:
Extract files into JDK/jre/lib/security folder (whichever version of JRE/JDK x64/x86 you are using).
Endpoints
For a Spring Boot Actuator application there are some additional management endpoints:
-
POST to
/env
to update theEnvironment
and rebind@ConfigurationProperties
and log levels -
/refresh
for re-loading the boot strap context and refreshing the@RefreshScope
beans -
/restart
for closing theApplicationContext
and restarting it (disabled by default) -
/pause
and/resume
for calling theLifecycle
methods (stop()
andstart()
on theApplicationContext
)
Spring Cloud Commons: Common Abstractions
Patterns such as service discovery, load balancing and circuit breakers lend themselves to a common abstraction layer that can be consumed by all Spring Cloud clients, independent of the implementation (e.g. discovery via Eureka or Consul).
Spring RestTemplate as a Load Balancer Client
RestTemplate
can be automatically configured to use ribbon. To create a load balanced RestTemplate
create a RestTemplate
@Bean
and use the @LoadBalanced
qualifier.
Warning
|
A RestTemplate bean is no longer created via auto configuration. It must be created by individual applications.
|
@Configuration
public class MyConfiguration {
@LoadBalanced
@Bean
RestTemplate restTemplate() {
return new RestTemplate();
}
}
public class MyClass {
@Autowired
private RestTemplate restTemplate;
public String doOtherStuff() {
String results = restTemplate.getForObject("http://stores/stores", String.class);
return results;
}
}
The URI needs to use a virtual host name (ie. service name, not a host name).
The Ribbon client is used to create a full physical address. See
RibbonAutoConfiguration
for details of how the RestTemplate
is set up.
Retrying Failed Requests
A load balanced RestTemplate
can be configured to retry failed requests.
By default this logic is disabled, you can enable it by setting
spring.cloud.loadbalancer.retry.enabled=true
and adding Spring Retry to your application’s classpath.
The load balanced RestTemplate
will
honor some of the Ribbon configuration values related to retrying failed requests.
The properties you can use are client.ribbon.MaxAutoRetries
,
client.ribbon.MaxAutoRetriesNextServer
, and client.ribbon.OkToRetryOnAllOperations
.
See the Ribbon documentation
for a description of what there properties do.
Note
|
client in the above examples should be replaced with your Ribbon client’s
name.
|
Multiple RestTemplate objects
If you want a RestTemplate
that is not load balanced, create a RestTemplate
bean and inject it as normal. To access the load balanced RestTemplate use
the `@LoadBalanced
qualifier when you create your @Bean
.
Important
|
Notice the @Primary annotation on the plain RestTemplate declaration in the example below, to disambiguate the unqualified @Autowired injection.
|
@Configuration
public class MyConfiguration {
@LoadBalanced
@Bean
RestTemplate loadBalanced() {
return new RestTemplate();
}
@Primary
@Bean
RestTemplate restTemplate() {
return new RestTemplate();
}
}
public class MyClass {
@Autowired
private RestTemplate restTemplate;
@Autowired
@LoadBalanced
private RestTemplate loadBalanced;
public String doOtherStuff() {
return loadBalanced.getForObject("http://stores/stores", String.class);
}
public String doStuff() {
return restTemplate.getForObject("http://example.com", String.class);
}
}
Tip
|
If you see errors like java.lang.IllegalArgumentException: Can not set org.springframework.web.client.RestTemplate field com.my.app.Foo.restTemplate to com.sun.proxy.$Proxy89 try injecting RestOperations instead or setting spring.aop.proxyTargetClass=true .
|
Ignore Network Interfaces
Sometimes it is useful to ignore certain named network interfaces so they can be excluded from Service Discovery registration (eg. running in a Docker container). A list of regular expressions can be set that will cause the desired network interfaces to be ignored. The following configuration will ignore the "docker0" interface and all interfaces that start with "veth".
spring: cloud: inetutils: ignoredInterfaces: - docker0 - veth.*
You can also force to use only specified network addresses using list of regular expressions:
spring: cloud: inetutils: preferredNetworks: - 192.168 - 10.0
You can also force to use only site local addresses. See Inet4Address.html.isSiteLocalAddress() for more details what is site local address.
spring: cloud: inetutils: useOnlySiteLocalInterfaces: true
Spring Cloud Config
Camden.SR7
Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With the Config Server you have a central place to manage external properties for applications across all environments. The concepts on both client and server map identically to the Spring Environment
and PropertySource
abstractions, so they fit very well with Spring applications, but can be used with any application running in any language. As an application moves through the deployment pipeline from dev to test and into production you can manage the configuration between those environments and be certain that applications have everything they need to run when they migrate. The default implementation of the server storage backend uses git so it easily supports labelled versions of configuration environments, as well as being accessible to a wide range of tooling for managing the content. It is easy to add alternative implementations and plug them in with Spring configuration.
Quick Start
Start the server:
$ cd spring-cloud-config-server $ ../mvnw spring-boot:run
The server is a Spring Boot application so you can run it from your
IDE instead if you prefer (the main class is
ConfigServerApplication
). Then try out a client:
$ curl localhost:8888/foo/development {"name":"development","label":"master","propertySources":[ {"name":"https://github.com/scratches/config-repo/foo-development.properties","source":{"bar":"spam"}}, {"name":"https://github.com/scratches/config-repo/foo.properties","source":{"foo":"bar"}} ]}
The default strategy for locating property sources is to clone a git
repository (at spring.cloud.config.server.git.uri
) and use it to
initialize a mini SpringApplication
. The mini-application’s
Environment
is used to enumerate property sources and publish them
via a JSON endpoint.
The HTTP service has resources in the form:
/{application}/{profile}[/{label}] /{application}-{profile}.yml /{label}/{application}-{profile}.yml /{application}-{profile}.properties /{label}/{application}-{profile}.properties
where the "application" is injected as the spring.config.name
in the
SpringApplication
(i.e. what is normally "application" in a regular
Spring Boot app), "profile" is an active profile (or comma-separated
list of properties), and "label" is an optional git label (defaults to
"master".)
Spring Cloud Config Server pulls configuration for remote clients from a git repository (which must be provided):
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
Client Side Usage
To use these features in an application, just build it as a Spring
Boot application that depends on spring-cloud-config-client (e.g. see
the test cases for the config-client, or the sample app). The most
convenient way to add the dependency is via a Spring Boot starter
org.springframework.cloud:spring-cloud-starter-config
. There is also a
parent pom and BOM (spring-cloud-starter-parent
) for Maven users and a
Spring IO version management properties file for Gradle and Spring CLI
users. Example Maven configuration:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.5.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-config</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<!-- repositories also needed for snapshots and milestones -->
Then you can create a standard Spring Boot application, like this simple HTTP server:
@SpringBootApplication @RestController public class Application { @RequestMapping("/") public String home() { return "Hello World!"; } public static void main(String[] args) { SpringApplication.run(Application.class, args); } }
When it runs it will pick up the external configuration from the
default local config server on port 8888 if it is running. To modify
the startup behaviour you can change the location of the config server
using bootstrap.properties
(like application.properties
but for
the bootstrap phase of an application context), e.g.
spring.cloud.config.uri: http://myconfigserver.com
The bootstrap properties will show up in the /env
endpoint as a
high-priority property source, e.g.
$ curl localhost:8080/env { "profiles":[], "configService:https://github.com/spring-cloud-samples/config-repo/bar.properties":{"foo":"bar"}, "servletContextInitParams":{}, "systemProperties":{...}, ... }
(a property source called "configService:<URL of remote repository>/<file name>" contains the property "foo" with value "bar" and is highest priority).
Note
|
the URL in the property source name is the git repository not the config server URL. |
Spring Cloud Config Server
The Server provides an HTTP, resource-based API for external
configuration (name-value pairs, or equivalent YAML content). The
server is easily embeddable in a Spring Boot application using the
@EnableConfigServer
annotation. So this app is a config server:
@SpringBootApplication
@EnableConfigServer
public class ConfigServer {
public static void main(String[] args) {
SpringApplication.run(ConfigServer.class, args);
}
}
Like all Spring Boot apps it runs on port 8080 by default, but you
can switch it to the conventional port 8888 in various ways. The
easiest, which also sets a default configuration repository,
is by launching it with spring.config.name=configserver
(there
is a configserver.yml
in the Config Server jar). Another is
to use your own application.properties
, e.g.
server.port: 8888
spring.cloud.config.server.git.uri: file://${user.home}/config-repo
where ${user.home}/config-repo
is a git repository containing
YAML and properties files.
Note
|
in Windows you need an extra "/" in the file URL if it is
absolute with a drive prefix, e.g. file:///${user.home}/config-repo .
|
Tip
|
Here’s a recipe for creating the git repository in the example above: $ cd $HOME $ mkdir config-repo $ cd config-repo $ git init . $ echo info.foo: bar > application.properties $ git add -A . $ git commit -m "Add application.properties" |
Warning
|
using the local filesystem for your git repository is intended for testing only. Use a server to host your configuration repositories in production. |
Warning
|
the initial clone of your configuration repository will be quick and efficient if you only keep text files in it. If you start to store binary files, especially large ones, you may experience delays on the first request for configuration and/or out of memory errors in the server. |
Environment Repository
Where do you want to store the configuration data for the Config
Server? The strategy that governs this behaviour is the
EnvironmentRepository
, serving Environment
objects. This
Environment
is a shallow copy of the domain from the Spring
Environment
(including propertySources
as the main feature). The
Environment
resources are parametrized by three variables:
-
{application}
maps to "spring.application.name" on the client side; -
{profile}
maps to "spring.profiles.active" on the client (comma separated list); and -
{label}
which is a server side feature labelling a "versioned" set of config files.
Repository implementations generally behave just like a Spring Boot
application loading configuration files from a "spring.config.name"
equal to the {application}
parameter, and "spring.profiles.active"
equal to the {profiles}
parameter. Precedence rules for profiles are
also the same as in a regular Boot application: active profiles take
precedence over defaults, and if there are multiple profiles the last
one wins (like adding entries to a Map
).
Example: a client application has this bootstrap configuration:
spring:
application:
name: foo
profiles:
active: dev,mysql
(as usual with a Spring Boot application, these properties could also be set as environment variables or command line arguments).
If the repository is file-based, the server will create an
Environment
from application.yml
(shared between all clients), and
foo.yml
(with foo.yml
taking precedence). If the YAML files have
documents inside them that point to Spring profiles, those are applied
with higher precedence (in order of the profiles listed), and if
there are profile-specific YAML (or properties) files these are also
applied with higher precedence than the defaults. Higher precedence
translates to a PropertySource
listed earlier in the
Environment
. (These are the same rules as apply in a standalone
Spring Boot application.)
Git Backend
The default implementation of EnvironmentRepository
uses a Git
backend, which is very convenient for managing upgrades and physical
environments, and also for auditing changes. To change the location of
the repository you can set the "spring.cloud.config.server.git.uri"
configuration property in the Config Server (e.g. in
application.yml
). If you set it with a file:
prefix it should work
from a local repository so you can get started quickly and easily
without a server, but in that case the server operates directly on the
local repository without cloning it (it doesn’t matter if it’s not
bare because the Config Server never makes changes to the "remote"
repository). To scale the Config Server up and make it highly
available, you would need to have all instances of the server pointing
to the same repository, so only a shared file system would work. Even
in that case it is better to use the ssh:
protocol for a shared
filesystem repository, so that the server can clone it and use a local
working copy as a cache.
This repository implementation maps the {label}
parameter of the
HTTP resource to a git label (commit id, branch name or tag). If the
git branch or tag name contains a slash ("/") then the label in the
HTTP URL should be specified with the special string "(_)" instead (to
avoid ambiguity with other URL paths). Be careful with the brackets in
the URL if you are using a command line client like curl (e.g. escape
them from the shell with quotes '').
Placeholders in Git URI
Spring Cloud Config Server supports a git repository URL with
placeholders for the {application}
and {profile}
(and {label}
if
you need it, but remember that the label is applied as a git label
anyway). So you can easily support a "one repo per application" policy
using (for example):
spring:
cloud:
config:
server:
git:
uri: https://github.com/myorg/{application}
or a "one repo per profile" policy using a similar pattern but with
{profile}
.
Pattern Matching and Multiple Repositories
There is also support for more complex requirements with pattern
matching on the application and profile name. The pattern format is a
comma-separated list of {application}/{profile}
names with wildcards
(where a pattern beginning with a wildcard may need to be
quoted). Example:
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
repos:
simple: https://github.com/simple/config-repo
special:
pattern: special*/dev*,*special*/dev*
uri: https://github.com/special/config-repo
local:
pattern: local*
uri: file:/home/configsvc/config-repo
If {application}/{profile}
does not match any of the patterns, it
will use the default uri defined under
"spring.cloud.config.server.git.uri". In the above example, for the
"simple" repository, the pattern is simple/*
(i.e. it only matches
one application named "simple" in all profiles). The "local"
repository matches all application names beginning with "local" in all
profiles (the /*
suffix is added automatically to any pattern that
doesn’t have a profile matcher).
Note
|
the "one-liner" short cut used in the "simple" example above can only be used if the only property to be set is the URI. If you need to set anything else (credentials, pattern, etc.) you need to use the full form. |
The pattern
property in the repo is actually an array, so you can
use a YAML array (or [0]
, [1]
, etc. suffixes in properties files)
to bind to multiple patterns. You may need to do this if you are going
to run apps with multiple profiles. Example:
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
repos:
development:
pattern:
- */development
- */staging
uri: https://github.com/development/config-repo
staging:
pattern:
- */qa
- */production
uri: https://github.com/staging/config-repo
Note
|
Spring Cloud will guess that a pattern containing a profile that
doesn’t end in * implies that you actually want to match a list of
profiles starting with this pattern (so */staging is a shortcut for
["*/staging", "*/staging,*"] ). This is common where you need to run
apps in the "development" profile locally but also the "cloud" profile
remotely, for instance.
|
Every repository can also optionally store config files in
sub-directories, and patterns to search for those directories can be
specified as searchPaths
. For example at the top level:
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
searchPaths: foo,bar*
In this example the server searches for config files in the top level and in the "foo/" sub-directory and also any sub-directory whose name begins with "bar".
By default the server clones remote repositories when configuration is first requested. The server can be configured to clone the repositories at startup. For example at the top level:
spring:
cloud:
config:
server:
git:
uri: https://git/common/config-repo.git
repos:
team-a:
pattern: team-a-*
cloneOnStart: true
uri: http://git/team-a/config-repo.git
team-b:
pattern: team-b-*
cloneOnStart: false
uri: http://git/team-b/config-repo.git
team-c:
pattern: team-c-*
uri: http://git/team-a/config-repo.git
In this example the server clones team-a’s config-repo on startup before it accepts any requests. All other repositories will not be cloned until configuration from the repository is requested.
Note
|
Setting a repository to be cloned when the Config Server starts up can
help to identify a misconfigured configuration source (e.g., an invalid
repository URI) quickly, while the Config Server is starting up. With
cloneOnStart not enabled for a configuration source, the Config Server may
start successfully with a misconfigured or invalid configuration source and
not detect an error until an application requests configuration from that
configuration source.
|
To use HTTP basic authentication on the remote repository add the "username" and "password" properties separately (not in the URL), e.g.
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
username: trolley
password: strongpassword
If you don’t use HTTPS and user credentials, SSH should also work out
of the box when you store keys in the default directories (~/.ssh
)
and the uri points to an SSH location,
e.g. "[email protected]:configuration/cloud-configuration". It is important that all
keys in ~/.ssh/known_hosts are in "ssh-rsa" format. The new "ecdsa-sha2-nistp256" format is NOT supported.
The repository is accessed using JGit, so any documentation you find on
that should be applicable. HTTPS proxy settings can be set in
~/.git/config
or in the same way as for any other JVM process via
system properties (-Dhttps.proxyHost
and -Dhttps.proxyPort
).
Tip
|
If you don’t know where your ~/.git directory is us git config
--global to manipulate the settings (e.g. git config --global
http.sslVerify false ).
|
Placeholders in Git Search Paths
Spring Cloud Config Server also supports a search path with
placeholders for the {application}
and {profile}
(and {label}
if
you need it). Example:
spring:
cloud:
config:
server:
git:
uri: https://github.com/spring-cloud-samples/config-repo
searchPaths: '{application}'
searches the repository for files in the same name as the directory (as well as the top level). Wildcards are also valid in a search path with placeholders (any matching directory is included in the search).
Version Control Backend Filesystem Use
Warning
|
With VCS based backends (git, svn) files are checked out or cloned to the local filesystem. By default they are put in the system temporary directory with a prefix of config-repo- . On linux, for example it could be /tmp/config-repo-<randomid> . Some operating systems routinely clean out temporary directories. This can lead to unexpected behaviour such as missing properties. To avoid this problem, change the directory Config Server uses, by setting spring.cloud.config.server.git.basedir or spring.cloud.config.server.svn.basedir to a directory that does not reside in the system temp structure.
|
File System Backend
There is also a "native" profile in the Config Server that doesn’t use Git, but just loads the config files from the local classpath or file system (any static URL you want to point to with "spring.cloud.config.server.native.searchLocations"). To use the native profile just launch the Config Server with "spring.profiles.active=native".
Note
|
Remember to use the file: prefix for file resources (the
default without a prefix is usually the classpath). Just as with any
Spring Boot configuration you can embed ${} -style environment
placeholders, but remember that absolute paths in Windows require an
extra "/", e.g. file:///${user.home}/config-repo
|
Warning
|
The default value of the searchLocations is identical to a
local Spring Boot application (so [classpath:/, classpath:/config,
file:./, file:./config] ). This does not expose the
application.properties from the server to all clients because any
property sources present in the server are removed before being sent
to the client.
|
Tip
|
A filesystem backend is great for getting started quickly and for testing. To use it in production you need to be sure that the file system is reliable, and shared across all instances of the Config Server. |
The search locations can contain placeholders for {application}
,
{profile}
and {label}
. In this way you can segregate the
directories in the path, and choose a strategy that makes sense for
you (e.g. sub-directory per application, or sub-directory per
profile).
If you don’t use placeholders in the search locations, this repository
also appends the {label}
parameter of the HTTP resource to a suffix
on the search path, so properties files are loaded from each search
location and a subdirectory with the same name as the label (the
labelled properties take precedence in the Spring Environment). Thus
the default behaviour with no placeholders is the same as adding a
search location ending with /{label}/. For example `file:/tmp/config
is the same as file:/tmp/config,file:/tmp/config/{label}
Vault Backend
Spring Cloud Config Server also supports Vault as a backend.
For more information on Vault see the Vault quickstart guide.
To enable the config server to use a Vault backend you must run your config server
with the vault
profile. For example in your config server’s application.properties
you can add spring.profiles.active=vault
.
By default the config server will assume your Vault server is running at
http://127.0.0.1:8200
. It also will assume that the name of backend
is secret
and the key is application
. All of these defaults can be
configured in your config server’s application.properties
. Below is a
table of configurable Vault properties. All properties are prefixed with
spring.cloud.config.server.vault
.
Name | Default Value |
---|---|
host |
127.0.0.1 |
port |
8200 |
scheme |
http |
backend |
secret |
defaultKey |
application |
profileSeparator |
, |
All configurable properties can be found in
org.springframework.cloud.config.server.environment.VaultEnvironmentRepository
.
With your config server running you can make HTTP requests to the server to retrieve values from the Vault backend. To do this you will need a token for your Vault server.
First place some data in you Vault. For example
$ vault write secret/application foo=bar baz=bam
$ vault write secret/myapp foo=myappsbar
Now make the HTTP request to your config server to retrieve the values.
$ curl -X "GET" "http://localhost:8888/myapp/default" -H "X-Config-Token: yourtoken"
You should see a response similar to this after making the above request.
{
"name":"myapp",
"profiles":[
"default"
],
"label":null,
"version":null,
"state":null,
"propertySources":[
{
"name":"vault:myapp",
"source":{
"foo":"myappsbar"
}
},
{
"name":"vault:application",
"source":{
"baz":"bam",
"foo":"bar"
}
}
]
}
Multiple Properties Sources
When using Vault you can provide your applications with multiple properties sources. For example, assume you have written data to the following paths in Vault.
secret/myApp,dev
secret/myApp
secret/application,dev
secret/application
Properties written to secret/application
are available to
all applications using the Config Server. An
application with the name myApp
would have any properties
written to secret/myApp
and secret/application
available to it.
When myApp
has the dev
profile enabled than properties written to
all of the above paths would be available to it, with properties in
the first path in the list taking priority over the others.
Sharing Configuration With All Applications
File Based Repositories
With file-based (i.e. git, svn and native) repositories, resources
with file names in application*
are shared between all client
applications (so application.properties
, application.yml
,
application-*.properties
etc.). You can use resources with these
file names to configure global defaults and have them overridden by
application-specific files as necessary.
The #_property_overrides[property overrides] feature can also be used for setting global defaults, and with placeholders applications are allowed to override them locally.
Tip
|
With the "native" profile (local file system backend) it is
recommended that you use an explicit search location that isn’t part
of the server’s own configuration. Otherwise the application*
resources in the default search locations are removed because they are
part of the server.
|
Vault Server
When using Vault as a backend you can share configuration with
all applications by placing configuration in
html5/application
. For example, if you run this Vault command
$ vault write secret/application foo=bar baz=bam
All applications using the config server will have the properties
foo
and baz
available to them.
Property Overrides
The Config Server has an "overrides" feature that allows the operator
to provide configuration properties to all applications that cannot be
accidentally changed by the application using the normal Spring Boot
hooks. To declare overrides just add a map of name-value pairs to
spring.cloud.config.server.overrides
. For example
spring:
cloud:
config:
server:
overrides:
foo: bar
will cause all applications that are config clients to read foo=bar
independent of their own configuration. (Of course an application can
use the data in the Config Server in any way it likes, so overrides
are not enforceable, but they do provide useful default behaviour if
they are Spring Cloud Config clients.)
Tip
|
Normal, Spring environment placeholders with "${}" can be escaped
(and resolved on the client) by using backslash ("\") to escape the
"$" or the "{", e.g. \${app.foo:bar} resolves to "bar" unless the
app provides its own "app.foo". Note that in YAML you don’t need to
escape the backslash itself, but in properties files you do, when you
configure the overrides on the server.
|
You can change the priority of all overrides in the client to be more
like default values, allowing applications to supply their own values
in environment variables or System properties, by setting the flag
spring.cloud.config.overrideNone=true
(default is false) in the
remote repository.
Health Indicator
Config Server comes with a Health Indicator that checks if the configured
EnvironmentRepository
is working. By default it asks the EnvironmentRepository
for an application named app
, the default
profile and the default
label provided by the EnvironmentRepository
implementation.
You can configure the Health Indicator to check more applications along with custom profiles and custom labels, e.g.
spring:
cloud:
config:
server:
health:
repositories:
myservice:
label: mylabel
myservice-dev:
name: myservice
profiles: development
You can disable the Health Indicator by setting spring.cloud.config.server.health.enabled=false
.
Security
You are free to secure your Config Server in any way that makes sense to you (from physical network security to OAuth2 bearer tokens), and Spring Security and Spring Boot make it easy to do pretty much anything.
To use the default Spring Boot configured HTTP Basic security, just
include Spring Security on the classpath (e.g. through
spring-boot-starter-security
). The default is a username of "user"
and a randomly generated password, which isn’t going to be very useful
in practice, so we recommend you configure the password (via
security.user.password
) and encrypt it (see below for instructions
on how to do that).
Encryption and Decryption
Important
|
Prerequisites: to use the encryption and decryption features you need the full-strength JCE installed in your JVM (it’s not there by default). You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" from Oracle, and follow instructions for installation (essentially replace the 2 policy files in the JRE lib/security directory with the ones that you downloaded). |
If the remote property sources contain encrypted content (values
starting with {cipher}
) they will be decrypted before sending to
clients over HTTP. The main advantage of this set up is that the
property values don’t have to be in plain text when they are "at rest"
(e.g. in a git repository). If a value cannot be decrypted it is
removed from the property source and an additional property is added
with the same key, but prefixed with "invalid." and a value that means
"not applicable" (usually "<n/a>"). This is largely to prevent cipher
text being used as a password and accidentally leaking.
If you are setting up a remote config repository for config client
applications it might contain an application.yml
like this, for
instance:
spring:
datasource:
username: dbuser
password: '{cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ'
Encrypted values in a .properties file must not be wrapped in quotes, otherwise the value will not be decrypted:
spring.datasource.username: dbuser spring.datasource.password: {cipher}FKSAJDFGYOS8F7GLHAKERGFHLSAJ
You can safely push this plain text to a shared git repository and the secret password is protected.
The server also exposes /encrypt
and /decrypt
endpoints (on the
assumption that these will be secured and only accessed by authorized
agents). If you are editing a remote config file you can use the Config Server
to encrypt values by POSTing to the /encrypt
endpoint, e.g.
$ curl localhost:8888/encrypt -d mysecret 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda
The inverse operation is also available via /decrypt
(provided the server is
configured with a symmetric key or a full key pair):
$ curl localhost:8888/decrypt -d 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda mysecret
Tip
|
If you are testing like this with curl, then use
--data-urlencode (instead of -d ) or set an explicit Content-Type:
text/plain to make sure curl encodes the data correctly when there
are special characters ('+' is particularly tricky).
|
Take the encrypted value and add the {cipher}
prefix before you put
it in the YAML or properties file, and before you commit and push it
to a remote, potentially insecure store.
The /encrypt
and /decrypt
endpoints also both accept paths of the
form /*/{name}/{profiles}
which can be used to control cryptography
per application (name) and profile when clients call into the main
Environment resource.
Note
|
to control the cryptography in this granular way you must also
provide a @Bean of type TextEncryptorLocator that creates a
different encryptor per name and profiles. The one that is provided
by default does not do this (so all encryptions use the same key).
|
The spring
command line client (with Spring Cloud CLI extensions
installed) can also be used to encrypt and decrypt, e.g.
$ spring encrypt mysecret --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda $ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda mysecret
To use a key in a file (e.g. an RSA public key for encryption) prepend the key value with "@" and provide the file path, e.g.
$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...
The key argument is mandatory (despite having a --
prefix).
Key Management
The Config Server can use a symmetric (shared) key or an asymmetric one (RSA key pair). The asymmetric choice is superior in terms of security, but it is often more convenient to use a symmetric key since it is just a single property value to configure.
To configure a symmetric key you just need to set encrypt.key
to a
secret String (or use an enviroment variable ENCRYPT_KEY
to keep it
out of plain text configuration files).
To configure an asymmetric key you can either set the key as a
PEM-encoded text value (in encrypt.key
), or via a keystore (e.g. as
created by the keytool
utility that comes with the JDK). The
keystore properties are encrypt.keyStore.*
with *
equal to
-
location
(aResource
location), -
password
(to unlock the keystore) and -
alias
(to identify which key in the store is to be used).
The encryption is done with the public key, and a private key is needed for decryption. Thus in principle you can configure only the public key in the server if you only want to do encryption (and are prepared to decrypt the values yourself locally with the private key). In practice you might not want to do that because it spreads the key management process around all the clients, instead of concentrating it in the server. On the other hand it’s a useful option if your config server really is relatively insecure and only a handful of clients need the encrypted properties.
Creating a Key Store for Testing
To create a keystore for testing you can do something like this:
$ keytool -genkeypair -alias mytestkey -keyalg RSA \ -dname "CN=Web Server,OU=Unit,O=Organization,L=City,S=State,C=US" \ -keypass changeme -keystore server.jks -storepass letmein
Put the server.jks
file in the classpath (for instance) and then in
your application.yml
for the Config Server:
encrypt:
keyStore:
location: classpath:/server.jks
password: letmein
alias: mytestkey
secret: changeme
Using Multiple Keys and Key Rotation
In addition to the {cipher}
prefix in encrypted property values, the
Config Server looks for {name:value}
prefixes (zero or many) before
the start of the (Base64 encoded) cipher text. The keys are passed to
a TextEncryptorLocator
which can do whatever logic it needs to
locate a TextEncryptor
for the cipher. If you have configured a
keystore (encrypt.keystore.location
) the default locator will look
for keys in the store with aliases as supplied by the "key" prefix,
i.e. with a cipher text like this:
foo:
bar: `{cipher}{key:testkey}...`
the locator will look for a key named "testkey". A secret can also be
supplied via a {secret:…}
value in the prefix, but if it is not
the default is to use the keystore password (which is what you get
when you build a keytore and don’t specify a secret). If you do
supply a secret it is recommended that you also encrypt the secrets
using a custom SecretLocator
.
Key rotation is hardly ever necessary on cryptographic grounds if the
keys are only being used to encrypt a few bytes of configuration data
(i.e. they are not being used elsewhere), but occasionally you might
need to change the keys if there is a security breach for instance. In
that case all the clients would need to change their source config
files (e.g. in git) and use a new {key:…}
prefix in all the
ciphers, checking beforehand of course that the key alias is available
in the Config Server keystore.
Tip
|
the {name:value} prefixes can also be added to plaintext posted
to the /encrypt endpoint, if you want to let the Config Server
handle all encryption as well as decryption.
|
Serving Encrypted Properties
Sometimes you want the clients to decrypt the configuration locally,
instead of doing it in the server. In that case you can still have
/encrypt and /decrypt endpoints (if you provide the encrypt.*
configuration to locate a key), but you need to explicitly switch off
the decryption of outgoing properties using
spring.cloud.config.server.encrypt.enabled=false
. If you don’t care
about the endpoints, then it should work if you configure neither the
key nor the enabled flag.
Serving Alternative Formats
The default JSON format from the environment endpoints is perfect for
consumption by Spring applications because it maps directly onto the
Environment
abstraction. If you prefer you can consume the same data
as YAML or Java properties by adding a suffix to the resource path
(".yml", ".yaml" or ".properties"). This can be useful for consumption
by applications that do not care about the structure of the JSON
endpoints, or the extra metadata they provide, for example an
application that is not using Spring might benefit from the simplicity
of this approach.
The YAML and properties representations have an additional flag
(provided as a boolean query parameter resolvePlaceholders
) to
signal that placeholders in the source documents, in the standard
Spring ${…}
form, should be resolved in the output where possible
before rendering. This is a useful feature for consumers that don’t
know about the Spring placeholder conventions.
Note
|
there are limitations in using the YAML or properties formats, mainly in relation to the loss of metadata. The JSON is structured as an ordered list of property sources, for example, with names that correlate with the source. The YAML and properties forms are coalesced into a single map, even if the origin of the values has multiple sources, and the names of the original source files are lost. The YAML representation is not necessarily a faithful representation of the YAML source in a backing repository either: it is constructed from a list of flat property sources, and assumptions have to be made about the form of the keys. |
Serving Plain Text
Instead of using the Environment
abstraction (or one of the
alternative representations of it in YAML or properties format) your
applications might need generic plain text configuration files,
tailored to their environment. The Config Server provides these
through an additional endpoint at /{name}/{profile}/{label}/{path}
where "name", "profile" and "label" have the same meaning as the
regular environment endpoint, but "path" is a file name
(e.g. log.xml
). The source files for this endpoint are located in
the same way as for the environment endpoints: the same search path is
used as for properties or YAML files, but instead of aggregating all
matching resources, only the first one to match is returned.
After a resource is located, placeholders in the normal format
(${…}
) are resolved using the effective Environment
for the
application name, profile and label supplied. In this way the resource
endpoint is tightly integrated with the environment
endpoints. Example, if you have this layout for a GIT (or SVN)
repository:
application.yml nginx.conf
where nginx.conf
looks like this:
server { listen 80; server_name ${nginx.server.name}; }
and application.yml
like this:
nginx:
server:
name: example.com
---
spring:
profiles: development
nginx:
server:
name: develop.com
then the /foo/default/master/nginx.conf
resource looks like this:
server { listen 80; server_name example.com; }
and /foo/development/master/nginx.conf
like this:
server { listen 80; server_name develop.com; }
Note
|
just like the source files for environment configuration, the
"profile" is used to resolve the file name, so if you want a
profile-specific file then /*/development/*/logback.xml will be
resolved by a file called logback-development.xml (in preference
to logback.xml ).
|
Embedding the Config Server
The Config Server runs best as a standalone application, but if you
need to you can embed it in another application. Just use the
@EnableConfigServer
annotation. An optional property that can be
useful in this case is spring.cloud.config.server.bootstrap
which is
a flag to indicate that the server should configure itself from its
own remote repository. The flag is off by default because it can delay
startup, but when embedded in another application it makes sense to
initialize the same way as any other application.
Note
|
It should be obvious, but remember that if you use the bootstrap
flag the config server will need to have its name and repository URI
configured in bootstrap.yml .
|
To change the location of the server endpoints you can (optionally)
set spring.cloud.config.server.prefix
, e.g. "/config", to serve the
resources under a prefix. The prefix should start but not end with a
"/". It is applied to the @RequestMappings
in the Config Server
(i.e. underneath the Spring Boot prefixes server.servletPath
and
server.contextPath
).
If you want to read the configuration for an application directly from
the backend repository (instead of from the config server) that’s
basically an embedded config server with no endpoints. You can switch
off the endpoints entirely if you don’t use the @EnableConfigServer
annotation (just set spring.cloud.config.server.bootstrap=true
).
Push Notifications and Spring Cloud Bus
Many source code repository providers (like Github, Gitlab or Bitbucket
for instance) will notify you of changes in a repository through a
webhook. You can configure the webhook via the provider’s user
interface as a URL and a set of events in which you are
interested. For instance
Github
will POST to the webhook with a JSON body containing a list of
commits, and a header "X-Github-Event" equal to "push". If you add a
dependency on the spring-cloud-config-monitor
library and activate
the Spring Cloud Bus in your Config Server, then a "/monitor" endpoint
is enabled.
When the webhook is activated the Config Server will send a
RefreshRemoteApplicationEvent
targeted at the applications it thinks
might have changed. The change detection can be strategized, but by
default it just looks for changes in files that match the application
name (e.g. "foo.properties" is targeted at the "foo" application, and
"application.properties" is targeted at all applications). The strategy
if you want to override the behaviour is PropertyPathNotificationExtractor
which accepts the request headers and body as parameters and returns a list
of file paths that changed.
The default configuration works out of the box with Github, Gitlab or
Bitbucket. In addition to the JSON notifications from Github, Gitlab
or Bitbucket you can trigger a change notification by POSTing to
"/monitor" with a form-encoded body parameters path={name}
. This will
broadcast to applications matching the "{name}" pattern (can contain
wildcards).
Note
|
the RefreshRemoteApplicationEvent will only be transmitted if
the spring-cloud-bus is activated in the Config Server and in the
client application.
|
Note
|
the default configuration also detects filesystem changes in local git repositories (the webhook is not used in that case but as soon as you edit a config file a refresh will be broadcast). |
Spring Cloud Config Client
A Spring Boot application can take immediate advantage of the Spring
Config Server (or other external property sources provided by the
application developer), and it will also pick up some additional
useful features related to Environment
change events.
Config First Bootstrap
This is the default behaviour for any application which has the Spring
Cloud Config Client on the classpath. When a config client starts up
it binds to the Config Server (via the bootstrap configuration
property spring.cloud.config.uri
) and initializes Spring
Environment
with remote property sources.
The net result of this is that all client apps that want to consume
the Config Server need a bootstrap.yml
(or an environment variable)
with the server address in spring.cloud.config.uri
(defaults to
"http://localhost:8888").
Discovery First Bootstrap
If you are using a `DiscoveryClient implementation, such as Spring Cloud Netflix and Eureka Service Discovery or Spring Cloud Consul (Spring Cloud Zookeeper does not support this yet), then you can have the Config Server register with the Discovery Service if you want to, but in the default "Config First" mode, clients won’t be able to take advantage of the registration.
If you prefer to use DiscoveryClient
to locate the Config Server, you can do
that by setting spring.cloud.config.discovery.enabled=true
(default
"false"). The net result of that is that client apps all need a
bootstrap.yml
(or an environment variable) with the appropriate discovery
configuration. For example, with Spring Cloud Netflix, you need to define the
Eureka server address, e.g. in eureka.client.serviceUrl.defaultZone
. The
price for using this option is an extra network round trip on start up to
locate the service registration. The benefit is that the Config Server
can change its co-ordinates, as long as the Discovery Service is a fixed point. The
default service id is "configserver" but you can change that on the
client with spring.cloud.config.discovery.serviceId
(and on the server
in the usual way for a service, e.g. by setting spring.application.name
).
The discovery client implementations all support some kind of metadata
map (e.g. for Eureka we have eureka.instance.metadataMap
). Some
additional properties of the Config Server may need to be configured
in its service registration metadata so that clients can connect
correctly. If the Config Server is secured with HTTP Basic you can
configure the credentials as "username" and "password". And if the
Config Server has a context path you can set "configPath". Example,
for a Config Server that is a Eureka client:
eureka:
instance:
...
metadataMap:
user: osufhalskjrtl
password: lviuhlszvaorhvlo5847
configPath: /config
Config Client Fail Fast
In some cases, it may be desirable to fail startup of a service if
it cannot connect to the Config Server. If this is the desired
behavior, set the bootstrap configuration property
spring.cloud.config.failFast=true
and the client will halt with
an Exception.
Config Client Retry
If you expect that the config server may occasionally be unavailable when
your app starts, you can ask it to keep trying after a failure. First you need
to set spring.cloud.config.failFast=true
, and then you need to add
spring-retry
and spring-boot-starter-aop
to your classpath. The default
behaviour is to retry 6 times with an initial backoff interval of 1000ms and an
exponential multiplier of 1.1 for subsequent backoffs. You can configure these
properties (and others) using spring.cloud.config.retry.*
configuration properties.
Tip
|
To take full control of the retry add a @Bean of type
RetryOperationsInterceptor with id "configServerRetryInterceptor". Spring
Retry has a RetryInterceptorBuilder that makes it easy to create one.
|
Locating Remote Configuration Resources
The Config Service serves property sources from /{name}/{profile}/{label}
, where the default bindings in the client app are
-
"name" =
${spring.application.name}
-
"profile" =
${spring.profiles.active}
(actuallyEnvironment.getActiveProfiles()
) -
"label" = "master"
All of them can be overridden by setting spring.cloud.config.*
(where *
is "name", "profile" or "label"). The "label" is useful for
rolling back to previous versions of configuration; with the default
Config Server implementation it can be a git label, branch name or
commit id. Label can also be provided as a comma-separated list, in
which case the items in the list are tried on-by-one until one succeeds.
This can be useful when working on a feature branch, for instance,
when you might want to align the config label with your branch, but
make it optional (e.g. spring.cloud.config.label=myfeature,develop
).
Security
If you use HTTP Basic security on the server then clients just need to know the password (and username if it isn’t the default). You can do that via the config server URI, or via separate username and password properties, e.g.
spring:
cloud:
config:
uri: https://user:[email protected]
or
spring:
cloud:
config:
uri: https://myconfig.mycompany.com
username: user
password: secret
The spring.cloud.config.password
and spring.cloud.config.username
values override anything that is provided in the URI.
If you deploy your apps on Cloud Foundry then the best way to provide the password is through service credentials, e.g. in the URI, since then it doesn’t even need to be in a config file. An example which works locally and for a user-provided service on Cloud Foundry named "configserver":
spring:
cloud:
config:
uri: ${vcap.services.configserver.credentials.uri:http://user:password@localhost:8888}
If you use another form of security you might need to provide a
RestTemplate
to the ConfigServicePropertySourceLocator
(e.g. by
grabbing it in the bootstrap context and injecting one).
Health Indicator
The Config Client supplies a Spring Boot Health Indicator that attempts to load configuration from Config Server. The health indicator can be disabled by setting health.config.enabled=false
. The response is also cached for performance reasons. The default cache time to live is 5 minutes. To change that value set the health.config.time-to-live
property (in milliseconds).
Providing A Custom RestTemplate
In some cases you might need to customize the requests made to the config server from
the client. Typically this involves passing special Authorization
headers to
authenticate requests to the server. To provide a custom RestTemplate
follow the
steps below.
-
Set
spring.cloud.config.enabled=false
to disable the existing config server property source. -
Create a new configuration bean with an implementation of
PropertySourceLocator
.
@Configuration
public class CustomConfigServiceBootstrapConfiguration {
@Bean
public ConfigClientProperties configClientProperties() {
ConfigClientProperties client = new ConfigClientProperties(this.environment);
client.setEnabled(false);
return client;
}
@Bean
public ConfigServicePropertySourceLocator configServicePropertySourceLocator() {
ConfigClientProperties clientProperties = configClientProperties();
ConfigServicePropertySourceLocator configServicePropertySourceLocator = new ConfigServicePropertySourceLocator(clientProperties);
configServicePropertySourceLocator.setRestTemplate(customRestTemplate(clientProperties));
return configServicePropertySourceLocator;
}
}
-
In
resources/META-INF
create a file calledspring.factories
and specify your custom configuration.
org.springframework.cloud.bootstrap.BootstrapConfiguration = com.my.config.client.CustomConfigServiceBootstrapConfiguration
Vault
When using Vault as a backend to your config server the client will need to
supply a token for the server to retrieve values from Vault. This token
can be provided within the client by setting spring.cloud.config.token
in bootstrap.yml
.
spring:
cloud:
config:
token: YourVaultToken
Vault
Nested Keys In Vault
Vault supports the ability to nest keys in a value stored in Vault. For example
echo -n '{"appA": {"secret": "appAsecret"}, "bar": "baz"}' | vault write secret/myapp -
This command will write a JSON object to your Vault. To access these values in Spring you would use the traditional dot(.) annotation. For example
@Value("${appA.secret}")
String name = "World";
The above code would set the name
variable to appAsecret
.
Spring Cloud Netflix
Camden.SR7
This project provides Netflix OSS integrations for Spring Boot apps through autoconfiguration and binding to the Spring Environment and other Spring programming model idioms. With a few simple annotations you can quickly enable and configure the common patterns inside your application and build large distributed systems with battle-tested Netflix components. The patterns provided include Service Discovery (Eureka), Circuit Breaker (Hystrix), Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon).
Service Discovery: Eureka Clients
Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Eureka is the Netflix Service Discovery Server and Client. The server can be configured and deployed to be highly available, with each server replicating state about the registered services to the others.
How to Include Eureka Client
To include Eureka Client in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-eureka
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Registering with Eureka
When a client registers with Eureka, it provides meta-data about itself such as host and port, health indicator URL, home page etc. Eureka receives heartbeat messages from each instance belonging to a service. If the heartbeat fails over a configurable timetable, the instance is normally removed from the registry.
Example eureka client:
@Configuration
@ComponentScan
@EnableAutoConfiguration
@EnableEurekaClient
@RestController
public class Application {
@RequestMapping("/")
public String home() {
return "Hello world";
}
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}
(i.e. utterly normal Spring Boot app). In this example we use
@EnableEurekaClient
explicitly, but with only Eureka available you
could also use @EnableDiscoveryClient
. Configuration is required to
locate the Eureka server. Example:
eureka: client: serviceUrl: defaultZone: http://localhost:8761/eureka/
where "defaultZone" is a magic string fallback value that provides the service URL for any client that doesn’t express a preference (i.e. it’s a useful default).
The default application name (service ID), virtual host and non-secure
port, taken from the Environment
, are ${spring.application.name}
,
${spring.application.name}
and ${server.port}
respectively.
@EnableEurekaClient
makes the app into both a Eureka "instance"
(i.e. it registers itself) and a "client" (i.e. it can query the
registry to locate other services). The instance behaviour is driven
by eureka.instance.*
configuration keys, but the defaults will be
fine if you ensure that your application has a
spring.application.name
(this is the default for the Eureka service
ID, or VIP).
See EurekaInstanceConfigBean and EurekaClientConfigBean for more details of the configurable options.
Authenticating with the Eureka Server
HTTP basic authentication will be automatically added to your eureka
client if one of the eureka.client.serviceUrl.defaultZone
URLs has
credentials embedded in it (curl style, like
http://user:password@localhost:8761/eureka
). For more complex needs
you can create a @Bean
of type DiscoveryClientOptionalArgs
and
inject ClientFilter
instances into it, all of which will be applied
to the calls from the client to the server.
Note
|
Because of a limitation in Eureka it isn’t possible to support per-server basic auth credentials, so only the first set that are found will be used. |
Status Page and Health Indicator
The status page and health indicators for a Eureka instance default to
"/info" and "/health" respectively, which are the default locations of
useful endpoints in a Spring Boot Actuator application. You need to
change these, even for an Actuator application if you use a
non-default context path or servlet path
(e.g. server.servletPath=/foo
) or management endpoint path
(e.g. management.contextPath=/admin
). Example:
eureka: instance: statusPageUrlPath: ${management.context-path}/info healthCheckUrlPath: ${management.context-path}/health
These links show up in the metadata that is consumed by clients, and used in some scenarios to decide whether to send requests to your application, so it’s helpful if they are accurate.
Registering a Secure Application
If your app wants to be contacted over HTTPS you can set two flags in
the EurekaInstanceConfig
, viz
eureka.instance.[nonSecurePortEnabled,securePortEnabled]=[false,true]
respectively. This will make Eureka publish instance information
showing an explicit preference for secure communication. The Spring
Cloud DiscoveryClient
will always return an https://…;
URI for a
service configured this way, and the Eureka (native) instance
information will have a secure health check URL.
Because of the way Eureka works internally, it will still publish a non-secure URL for status and home page unless you also override those explicitly. You can use placeholders to configure the eureka instance urls, e.g.
eureka: instance: statusPageUrl: https://${eureka.hostname}/info healthCheckUrl: https://${eureka.hostname}/health homePageUrl: https://${eureka.hostname}/
(Note that ${eureka.hostname}
is a native placeholder only available
in later versions of Eureka. You could achieve the same thing with
Spring placeholders as well, e.g. using ${eureka.instance.hostName}
.)
Note
|
If your app is running behind a proxy, and the SSL termination is in the proxy (e.g. if you run in Cloud Foundry or other platforms as a service) then you will need to ensure that the proxy "forwarded" headers are intercepted and handled by the application. An embedded Tomcat container in a Spring Boot app does this automatically if it has explicit configuration for the 'X-Forwarded-\*` headers. A sign that you got this wrong will be that the links rendered by your app to itself will be wrong (the wrong host, port or protocol). |
Eureka’s Health Checks
By default, Eureka uses the client heartbeat to determine if a client is up. Unless specified otherwise the Discovery Client will not propagate the current health check status of the application per the Spring Boot Actuator. Which means that after successful registration Eureka will always announce that the application is in 'UP' state. This behaviour can be altered by enabling Eureka health checks, which results in propagating application status to Eureka. As a consequence every other application won’t be sending traffic to application in state other then 'UP'.
eureka: client: healthcheck: enabled: true
Warning
|
eureka.client.healthcheck.enabled=true should only be set in application.yml . Setting the value in bootstrap.yml will cause undesirable side effects like registering in eureka with an UNKNOWN status.
|
If you require more control over the health checks, you may consider
implementing your own com.netflix.appinfo.HealthCheckHandler
.
Eureka Metadata for Instances and Clients
It’s worth spending a bit of time understanding how the Eureka metadata works, so you can use it in a way that makes sense in your platform. There is standard metadata for things like hostname, IP address, port numbers, status page and health check. These are published in the service registry and used by clients to contact the services in a straightforward way. Additional metadata can be added to the instance registration in the eureka.instance.metadataMap
, and this will be accessible in the remote clients, but in general will not change the behaviour of the client, unless it is made aware of the meaning of the metadata. There are a couple of special cases described below where Spring Cloud already assigns meaning to the metadata map.
Using Eureka on Cloudfoundry
Cloudfoundry has a global router so that all instances of the same app have the same hostname (it’s the same in other PaaS solutions with a similar architecture). This isn’t necessarily a barrier to using Eureka, but if you use the router (recommended, or even mandatory depending on the way your platform was set up), you need to explicitly set the hostname and port numbers (secure or non-secure) so that they use the router. You might also want to use instance metadata so you can distinguish between the instances on the client (e.g. in a custom load balancer). By default, the eureka.instance.instanceId
is vcap.application.instance_id
. For example:
eureka: instance: hostname: ${vcap.application.uris[0]} nonSecurePort: 80
Depending on the way the security rules are set up in your Cloudfoundry instance, you might be able to register and use the IP address of the host VM for direct service-to-service calls. This feature is not (yet) available on Pivotal Web Services (PWS).
Using Eureka on AWS
If the application is planned to be deployed to an AWS cloud, then the Eureka instance will have to be configured to be Amazon aware and this can be done by customizing the EurekaInstanceConfigBean the following way:
@Bean
@Profile("!default")
public EurekaInstanceConfigBean eurekaInstanceConfig() {
EurekaInstanceConfigBean b = new EurekaInstanceConfigBean();
AmazonInfo info = AmazonInfo.Builder.newBuilder().autoBuild("eureka");
b.setDataCenterInfo(info);
return b;
}
Changing the Eureka Instance ID
A vanilla Netflix Eureka instance is registered with an ID that is equal to its host name (i.e. only one service per host). Spring Cloud Eureka provides a sensible default that looks like this: ${spring.cloud.client.hostname}:${spring.application.name}:${spring.application.instance_id:${server.port}}}
. For example myhost:myappname:8080
.
Using Spring Cloud you can override this by providing a unique identifier in eureka.instance.instanceId
. For example:
eureka: instance: instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}
With this metadata, and multiple service instances deployed on
localhost, the random value will kick in there to make the instance
unique. In Cloudfoundry the vcap.application.instance_id
will be
populated automatically in a Spring Boot application, so the
random value will not be needed.
Using the EurekaClient
Once you have an app that is @EnableDiscoveryClient
(or @EnableEurekaClient
) you can use it to
discover service instances from the Eureka Server. One way to do that is to use the native
com.netflix.discovery.EurekaClient
(as opposed to the Spring
Cloud DiscoveryClient
), e.g.
@Autowired private EurekaClient discoveryClient; public String serviceUrl() { InstanceInfo instance = discoveryClient.getNextServerFromEureka("STORES", false); return instance.getHomePageUrl(); }
Tip
|
Don’t use the |
Alternatives to the native Netflix EurekaClient
You don’t have to use the raw Netflix EurekaClient
and usually it
is more convenient to use it behind a wrapper of some sort. Spring
Cloud has support for Feign (a REST client
builder) and also Spring RestTemplate
using
the logical Eureka service identifiers (VIPs) instead of physical
URLs. To configure Ribbon with a fixed list of physical servers you
can simply set <client>.ribbon.listOfServers
to a comma-separated
list of physical addresses (or hostnames), where <client>
is the ID
of the client.
You can also use the org.springframework.cloud.client.discovery.DiscoveryClient
which provides a simple API for discovery clients that is not specific
to Netflix, e.g.
@Autowired private DiscoveryClient discoveryClient; public String serviceUrl() { List<ServiceInstance> list = discoveryClient.getInstances("STORES"); if (list != null && list.size() > 0 ) { return list.get(0).getUri(); } return null; }
Why is it so Slow to Register a Service?
Being an instance also involves a periodic heartbeat to the registry
(via the client’s serviceUrl
) with default duration 30 seconds. A
service is not available for discovery by clients until the instance,
the server and the client all have the same metadata in their local
cache (so it could take 3 heartbeats). You can change the period using
eureka.instance.leaseRenewalIntervalInSeconds
and this will speed up
the process of getting clients connected to other services. In
production it’s probably better to stick with the default because
there are some computations internally in the server that make
assumptions about the lease renewal period.
Service Discovery: Eureka Server
How to Include Eureka Server
To include Eureka Server in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-eureka-server
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
How to Run a Eureka Server
Example eureka server;
@SpringBootApplication
@EnableEurekaServer
public class Application {
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}
The server has a home page with a UI, and HTTP API endpoints per the
normal Eureka functionality under /eureka/*
.
Eureka background reading: see flux capacitor and google group discussion.
Tip
|
Due to Gradle’s dependency resolution rules and the lack of a parent bom feature, simply depending on spring-cloud-starter-eureka-server can cause failures on application startup. To remedy this the Spring Boot Gradle plugin must be added and the Spring cloud starter parent bom must be imported like so: build.gradle
|
High Availability, Zones and Regions
The Eureka server does not have a backend store, but the service instances in the registry all have to send heartbeats to keep their registrations up to date (so this can be done in memory). Clients also have an in-memory cache of eureka registrations (so they don’t have to go to the registry for every single request to a service).
By default every Eureka server is also a Eureka client and requires (at least one) service URL to locate a peer. If you don’t provide it the service will run and work, but it will shower your logs with a lot of noise about not being able to register with the peer.
See also below for details of Ribbon support on the client side for Zones and Regions.
Standalone Mode
The combination of the two caches (client and server) and the heartbeats make a standalone Eureka server fairly resilient to failure, as long as there is some sort of monitor or elastic runtime keeping it alive (e.g. Cloud Foundry). In standalone mode, you might prefer to switch off the client side behaviour, so it doesn’t keep trying and failing to reach its peers. Example:
server: port: 8761 eureka: instance: hostname: localhost client: registerWithEureka: false fetchRegistry: false serviceUrl: defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
Notice that the serviceUrl
is pointing to the same host as the local
instance.
Peer Awareness
Eureka can be made even more resilient and available by running
multiple instances and asking them to register with each other. In
fact, this is the default behaviour, so all you need to do to make it
work is add a valid serviceUrl
to a peer, e.g.
--- spring: profiles: peer1 eureka: instance: hostname: peer1 client: serviceUrl: defaultZone: http://peer2/eureka/ --- spring: profiles: peer2 eureka: instance: hostname: peer2 client: serviceUrl: defaultZone: http://peer1/eureka/
In this example we have a YAML file that can be used to run the same
server on 2 hosts (peer1 and peer2), by running it in different
Spring profiles. You could use this configuration to test the peer
awareness on a single host (there’s not much value in doing that in
production) by manipulating /etc/hosts
to resolve the host names. In
fact, the eureka.instance.hostname
is not needed if you are running
on a machine that knows its own hostname (it is looked up using
java.net.InetAddress
by default).
You can add multiple peers to a system, and as long as they are all connected to each other by at least one edge, they will synchronize the registrations amongst themselves. If the peers are physically separated (inside a data centre or between multiple data centres) then the system can in principle survive split-brain type failures.
Prefer IP Address
In some cases, it is preferable for Eureka to advertise the IP Adresses
of services rather than the hostname. Set eureka.instance.preferIpAddress
to true
and when the application registers with eureka, it will use its
IP Address rather than its hostname.
Circuit Breaker: Hystrix Clients
Netflix has created a library called Hystrix that implements the circuit breaker pattern. In a microservice architecture it is common to have multiple layers of service calls.
A service failure in the lower level of services can cause cascading failure all the way up to the user. When calls to a particular service reach a certain threshold (20 failures in 5 seconds is the default in Hystrix), the circuit opens and the call is not made. In cases of error and an open circuit a fallback can be provided by the developer.
Having an open circuit stops cascading failures and allows overwhelmed or failing services time to heal. The fallback can be another Hystrix protected call, static data or a sane empty value. Fallbacks may be chained so the first fallback makes some other business call which in turn falls back to static data.
How to Include Hystrix
To include Hystrix in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-hystrix
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Example boot app:
@SpringBootApplication @EnableCircuitBreaker public class Application { public static void main(String[] args) { new SpringApplicationBuilder(Application.class).web(true).run(args); } } @Component public class StoreIntegration { @HystrixCommand(fallbackMethod = "defaultStores") public Object getStores(Map<String, Object> parameters) { //do stuff that might fail } public Object defaultStores(Map<String, Object> parameters) { return /* something useful */; } }
The @HystrixCommand
is provided by a Netflix contrib library called
"javanica".
Spring Cloud automatically wraps Spring beans with that
annotation in a proxy that is connected to the Hystrix circuit
breaker. The circuit breaker calculates when to open and close the
circuit, and what to do in case of a failure.
To configure the @HystrixCommand
you can use the commandProperties
attribute with a list of @HystrixProperty
annotations. See
here
for more details. See the Hystrix wiki
for details on the properties available.
Propagating the Security Context or using Spring Scopes
If you want some thread local context to propagate into a @HystrixCommand
the default declaration will not work because it executes the command in a thread pool (in case of timeouts). You can switch Hystrix to use the same thread as the caller using some configuration, or directly in the annotation, by asking it to use a different "Isolation Strategy". For example:
@HystrixCommand(fallbackMethod = "stubMyService",
commandProperties = {
@HystrixProperty(name="execution.isolation.strategy", value="SEMAPHORE")
}
)
...
The same thing applies if you are using @SessionScope
or @RequestScope
. You will know when you need to do this because of a runtime exception that says it can’t find the scoped context.
You also have the option to set the hystrix.shareSecurityContext
property to true
. Doing so will auto configure an Hystrix concurrency strategy plugin hook who will transfer the SecurityContext
from your main thread to the one used by the Hystrix command. Hystrix does not allow multiple hystrix concurrency strategy to be registered so an extension mechanism is available by declaring your own HystrixConcurrencyStrategy
as a Spring bean. Spring Cloud will lookup for your implementation within the Spring context and wrap it inside its own plugin.
Health Indicator
The state of the connected circuit breakers are also exposed in the
/health
endpoint of the calling application.
{
"hystrix": {
"openCircuitBreakers": [
"StoreIntegration::getStoresByLocationLink"
],
"status": "CIRCUIT_OPEN"
},
"status": "UP"
}
Hystrix Metrics Stream
To enable the Hystrix metrics stream include a dependency on spring-boot-starter-actuator
. This will expose the /hystrix.stream
as a management endpoint.
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
Circuit Breaker: Hystrix Dashboard
One of the main benefits of Hystrix is the set of metrics it gathers about each HystrixCommand. The Hystrix Dashboard displays the health of each circuit breaker in an efficient manner.
How to Include Hystrix Dashboard
To include the Hystrix Dashboard in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-hystrix-dashboard
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
To run the Hystrix Dashboard annotate your Spring Boot main class with @EnableHystrixDashboard
. You then visit /hystrix
and point the dashboard to an individual instances /hystrix.stream
endpoint in a Hystrix client application.
Turbine
Looking at an individual instances Hystrix data is not very useful in terms of the overall health of the system. Turbine is an application that aggregates all of the relevant /hystrix.stream
endpoints into a combined /turbine.stream
for use in the Hystrix Dashboard. Individual instances are located via Eureka. Running Turbine is as simple as annotating your main class with the @EnableTurbine
annotation (e.g. using spring-cloud-starter-turbine to set up the classpath). All of the documented configuration properties from the Turbine 1 wiki apply. The only difference is that the turbine.instanceUrlSuffix
does not need the port prepended as this is handled automatically unless turbine.instanceInsertPort=false
.
Note
|
By default, Turbine looks for the /hystrix.stream endpoint on a registered instance by looking up its homePageUrl entry in Eureka, then appending /hystrix.stream to it. This means that if spring-boot-actuator is running on its own port (which is the default), the call to /hystrix.stream will fail.
To make turbine find the Hystrix stream at the correct port, you need to add management.port to the instances' metadata:
|
eureka: instance: metadata-map: management.port: ${management.port:8081}
The configuration key turbine.appConfig
is a list of eureka serviceIds that turbine will use to lookup instances. The turbine stream is then used in the Hystrix dashboard using a url that looks like: http://my.turbine.sever:8080/turbine.stream?cluster=<CLUSTERNAME>
(the cluster parameter can be omitted if the name is "default"). The cluster
parameter must match an entry in turbine.aggregator.clusterConfig
. Values returned from eureka are uppercase, thus we expect this example to work if there is an app registered with Eureka called "customers":
turbine: aggregator: clusterConfig: CUSTOMERS appConfig: customers
The clusterName
can be customized by a SPEL expression in turbine.clusterNameExpression
with root an instance of InstanceInfo
. The default value is appName
, which means that the Eureka serviceId ends up as the cluster key (i.e. the InstanceInfo
for customers has an appName
of "CUSTOMERS"). A different example would be turbine.clusterNameExpression=aSGName
, which would get the cluster name from the AWS ASG name. Another example:
turbine: aggregator: clusterConfig: SYSTEM,USER appConfig: customers,stores,ui,admin clusterNameExpression: metadata['cluster']
In this case, the cluster name from 4 services is pulled from their metadata map, and is expected to have values that include "SYSTEM" and "USER".
To use the "default" cluster for all apps you need a string literal expression (with single quotes, and escaped with double quotes if it is in YAML as well):
turbine: appConfig: customers,stores clusterNameExpression: "'default'"
Spring Cloud provides a spring-cloud-starter-turbine
that has all the dependencies you need to get a Turbine server running. Just create a Spring Boot application and annotate it with @EnableTurbine
.
Note
|
by default Spring Cloud allows Turbine to use the host and port to allow multiple processes per host, per cluster. If you want the native Netflix behaviour built into Turbine that does not allow multiple processes per host, per cluster (the key to the instance id is the hostname), then set the property turbine.combineHostPort=false .
|
Turbine Stream
In some environments (e.g. in a PaaS setting), the classic Turbine model of pulling metrics from all the distributed Hystrix commands doesn’t work. In that case you might want to have your Hystrix commands push metrics to Turbine, and Spring Cloud enables that with messaging. All you need to do on the client is add a dependency to spring-cloud-netflix-hystrix-stream
and the spring-cloud-starter-stream-*
of your choice (see Spring Cloud Stream documentation for details on the brokers, and how to configure the client credentials, but it should work out of the box for a local broker).
On the server side Just create a Spring Boot application and annotate it with @EnableTurbineStream
and by default it will come up on port 8989 (point your Hystrix dashboard to that port, any path). You can customize the port using either server.port
or turbine.stream.port
. If you have spring-boot-starter-web
and spring-boot-starter-actuator
on the classpath as well, then you can open up the Actuator endpoints on a separate port (with Tomcat by default) by providing a management.port
which is different.
You can then point the Hystrix Dashboard to the Turbine Stream Server instead of individual Hystrix streams. If Turbine Stream is running on port 8989 on myhost, then put http://myhost:8989
in the stream input field in the Hystrix Dashboard. Circuits will be prefixed by their respective serviceId, followed by a dot, then the circuit name.
Spring Cloud provides a spring-cloud-starter-turbine-stream
that has all the dependencies you need to get a Turbine Stream server running - just add the Stream binder of your choice, e.g. spring-cloud-starter-stream-rabbit
. You need Java 8 to run the app because it is Netty-based.
Client Side Load Balancer: Ribbon
Ribbon is a client side load balancer which gives you a lot of control
over the behaviour of HTTP and TCP clients. Feign already uses Ribbon,
so if you are using @FeignClient
then this section also applies.
A central concept in Ribbon is that of the named client. Each load
balancer is part of an ensemble of components that work together to
contact a remote server on demand, and the ensemble has a name that
you give it as an application developer (e.g. using the @FeignClient
annotation). Spring Cloud creates a new ensemble as an
ApplicationContext
on demand for each named client using
RibbonClientConfiguration
. This contains (amongst other things) an
ILoadBalancer
, a RestClient
, and a ServerListFilter
.
How to Include Ribbon
To include Ribbon in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-ribbon
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Customizing the Ribbon Client
You can configure some bits of a Ribbon client using external
properties in <client>.ribbon.*
, which is no different than using
the Netflix APIs natively, except that you can use Spring Boot
configuration files. The native options can
be inspected as static fields in CommonClientConfigKey
(part of
ribbon-core).
Spring Cloud also lets you take full control of the client by
declaring additional configuration (on top of the
RibbonClientConfiguration
) using @RibbonClient
. Example:
@Configuration
@RibbonClient(name = "foo", configuration = FooConfiguration.class)
public class TestConfiguration {
}
In this case the client is composed from the components already in
RibbonClientConfiguration
together with any in FooConfiguration
(where the latter generally will override the former).
Warning
|
The FooConfiguration has to be @Configuration but take
care that it is not in a @ComponentScan for the main application
context, otherwise it will be shared by all the @RibbonClients . If
you use @ComponentScan (or @SpringBootApplication ) you need to
take steps to avoid it being included (for instance put it in a
separate, non-overlapping package, or specify the packages to scan
explicitly in the @ComponentScan ).
|
Spring Cloud Netflix provides the following beans by default for ribbon
(BeanType
beanName: ClassName
):
-
IClientConfig
ribbonClientConfig:DefaultClientConfigImpl
-
IRule
ribbonRule:ZoneAvoidanceRule
-
IPing
ribbonPing:NoOpPing
-
ServerList<Server>
ribbonServerList:ConfigurationBasedServerList
-
ServerListFilter<Server>
ribbonServerListFilter:ZonePreferenceServerListFilter
-
ILoadBalancer
ribbonLoadBalancer:ZoneAwareLoadBalancer
Creating a bean of one of those type and placing it in a @RibbonClient
configuration (such as FooConfiguration
above) allows you to override each
one of the beans described. Example:
@Configuration
public class FooConfiguration {
@Bean
public IPing ribbonPing(IClientConfig config) {
return new PingUrl();
}
}
This replaces the NoOpPing
with PingUrl
.
Customizing the Ribbon Client using properties
Starting with version 1.2.0, Spring Cloud Netflix now supports customizing Ribbon clients using properties to be compatible with the Ribbon documentation.
This allows you to change behavior at start up time in different environments.
The supported properties are listed below and should be prefixed by <clientName>.ribbon.
:
-
NFLoadBalancerClassName
: should implementILoadBalancer
-
NFLoadBalancerRuleClassName
: should implementIRule
-
NFLoadBalancerPingClassName
: should implementIPing
-
NIWSServerListClassName
: should implementServerList
-
NIWSServerListFilterClassName
should implementServerListFilter
Note
|
Classes defined in these properties have precedence over beans defined using @RibbonClient(configuration=MyRibbonConfig.class) and the defaults provided by Spring Cloud Netflix.
|
To set the IRule
for a service name users
you could set the following:
users: ribbon: NFLoadBalancerRuleClassName: com.netflix.loadbalancer.WeightedResponseTimeRule
See the Ribbon documentation for implementations provided by Ribbon.
Using Ribbon with Eureka
When Eureka is used in conjunction with Ribbon (i.e., both are on the classpath) the ribbonServerList
is overridden with an extension of DiscoveryEnabledNIWSServerList
which populates the list of servers from Eureka. It also replaces the
IPing
interface with NIWSDiscoveryPing
which delegates to Eureka
to determine if a server is up. The ServerList
that is installed by
default is a DomainExtractingServerList
and the purpose of this is
to make physical metadata available to the load balancer without using
AWS AMI metadata (which is what Netflix relies on). By default the
server list will be constructed with "zone" information as provided in
the instance metadata (so on the remote clients set
eureka.instance.metadataMap.zone
), and if that is missing it can use
the domain name from the server hostname as a proxy for zone (if the
flag approximateZoneFromHostname
is set). Once the zone information
is available it can be used in a ServerListFilter
. By default it
will be used to locate a server in the same zone as the client because
the default is a ZonePreferenceServerListFilter
. The zone of the
client is determined the same way as the remote instances by default,
i.e. via eureka.instance.metadataMap.zone
.
Note
|
The orthodox "archaius" way to set the client zone is via a configuration property called "@zone", and Spring Cloud will use that in preference to all other settings if it is available (note that the key will have to be quoted in YAML configuration). |
Note
|
If there is no other source of zone data then a guess is made
based on the client configuration (as opposed to the instance
configuration). We take eureka.client.availabilityZones , which is a
map from region name to a list of zones, and pull out the first zone
for the instance’s own region (i.e. the eureka.client.region , which
defaults to "us-east-1" for comatibility with native Netflix).
|
Example: How to Use Ribbon Without Eureka
Eureka is a convenient way to abstract the discovery of remote servers
so you don’t have to hard code their URLs in clients, but if you
prefer not to use it, Ribbon and Feign are still quite
amenable. Suppose you have declared a @RibbonClient
for "stores",
and Eureka is not in use (and not even on the classpath). The Ribbon
client defaults to a configured server list, and you can supply the
configuration like this
stores: ribbon: listOfServers: example.com,google.com
Example: Disable Eureka use in Ribbon
Setting the property ribbon.eureka.enabled = false
will explicitly
disable the use of Eureka in Ribbon.
ribbon: eureka: enabled: false
Using the Ribbon API Directly
You can also use the LoadBalancerClient
directly. Example:
public class MyClass {
@Autowired
private LoadBalancerClient loadBalancer;
public void doStuff() {
ServiceInstance instance = loadBalancer.choose("stores");
URI storesUri = URI.create(String.format("http://%s:%s", instance.getHost(), instance.getPort()));
// ... do something with the URI
}
}
Declarative REST Client: Feign
Feign is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same HttpMessageConverters
used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.
How to Include Feign
To include Feign in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-feign
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Example spring boot app
@Configuration
@ComponentScan
@EnableAutoConfiguration
@EnableEurekaClient
@EnableFeignClients
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
@FeignClient("stores")
public interface StoreClient {
@RequestMapping(method = RequestMethod.GET, value = "/stores")
List<Store> getStores();
@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
Store update(@PathVariable("storeId") Long storeId, Store store);
}
In the @FeignClient
annotation the String value ("stores" above) is
an arbitrary client name, which is used to create a Ribbon load
balancer (see below for details of Ribbon
support). You can also specify a URL using the url
attribute
(absolute value or just a hostname). The name of the bean in the
application context is the fully qualified name of the interface.
An alias is also created which is the 'name' attribute plus 'FeignClient'.
For the example above, @Qualifier("storesFeignClient")
could be used to
reference the bean. If you want to change the default @Qualifier
value,
this can be done with the qualifier
value in @FeignClient
.
The Ribbon client above will want to discover the physical addresses for the "stores" service. If your application is a Eureka client then it will resolve the service in the Eureka service registry. If you don’t want to use Eureka, you can simply configure a list of servers in your external configuration (see above for example).
Overriding Feign Defaults
A central concept in Spring Cloud’s Feign support is that of the named client. Each feign client is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer using the @FeignClient
annotation. Spring Cloud creates a new ensemble as an
ApplicationContext
on demand for each named client using FeignClientsConfiguration
. This contains (amongst other things) an feign.Decoder
, a feign.Encoder
, and a feign.Contract
.
Spring Cloud lets you take full control of the feign client by declaring additional configuration (on top of the FeignClientsConfiguration
) using @FeignClient
. Example:
@FeignClient(name = "stores", configuration = FooConfiguration.class)
public interface StoreClient {
//..
}
In this case the client is composed from the components already in FeignClientsConfiguration
together with any in FooConfiguration
(where the latter will override the former).
Warning
|
The FooConfiguration has to be @Configuration but take care that it is not in a @ComponentScan for the main application context, otherwise it will be used for every @FeignClient . If you use @ComponentScan (or @SpringBootApplication ) you need to take steps to avoid it being included (for instance put it in a separate, non-overlapping package, or specify the packages to scan explicitly in the @ComponentScan ).
|
Note
|
The serviceId attribute is now deprecated in favor of the name attribute.
|
Warning
|
Previously, using the url attribute, did not require the name attribute. Using name is now required.
|
Placeholders are supported in the name
and url
attributes.
@FeignClient(name = "${feign.name}", url = "${feign.url}")
public interface StoreClient {
//..
}
Spring Cloud Netflix provides the following beans by default for feign (BeanType
beanName: ClassName
):
-
Decoder
feignDecoder:ResponseEntityDecoder
(which wraps aSpringDecoder
) -
Encoder
feignEncoder:SpringEncoder
-
Logger
feignLogger:Slf4jLogger
-
Contract
feignContract:SpringMvcContract
-
Feign.Builder
feignBuilder:HystrixFeign.Builder
-
Client
feignClient: if Ribbon is enabled it is aLoadBalancerFeignClient
, otherwise the default feign client is used.
The OkHttpClient and ApacheHttpClient feign clients can be used by setting feign.okhttp.enabled
or feign.httpclient.enabled
to true
, respectively, and having them on the classpath.
Spring Cloud Netflix does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:
-
Logger.Level
-
Retryer
-
ErrorDecoder
-
Request.Options
-
Collection<RequestInterceptor>
Creating a bean of one of those type and placing it in a @FeignClient
configuration (such as FooConfiguration
above) allows you to override each one of the beans described. Example:
@Configuration
public class FooConfiguration {
@Bean
public Contract feignContract() {
return new feign.Contract.Default();
}
@Bean
public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
return new BasicAuthRequestInterceptor("user", "password");
}
}
This replaces the SpringMvcContract
with feign.Contract.Default
and adds a RequestInterceptor
to the collection of RequestInterceptor
.
Default configurations can be specified in the @EnableFeignClients
attribute defaultConfiguration
in a similar manner as described above. The difference is that this configuration will apply to all feign clients.
Creating Feign Clients Manually
In some cases it might be necessary to customize your Feign Clients in a way that is not possible using the methods above. In this case you can create Clients using the Feign Builder API. Below is an example which creates two Feign Clients with the same interface but configures each one with a separate request interceptor.
@Import(FeignClientsConfiguration.class)
class FooController {
private FooClient fooClient;
private FooClient adminClient;
@Autowired
public FooController(
ResponseEntityDecoder decoder, SpringEncoder encoder, Client client) {
this.fooClient = Feign.builder().client(client)
.encoder(encoder)
.decoder(decoder)
.requestInterceptor(new BasicAuthRequestInterceptor("user", "user"))
.target(FooClient.class, "http://PROD-SVC");
this.adminClient = Feign.builder().client(client)
.encoder(encoder)
.decoder(decoder)
.requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin"))
.target(FooClient.class, "http://PROD-SVC");
}
}
Note
|
In the above example FeignClientsConfiguration.class is the default configuration
provided by Spring Cloud Netflix.
|
Note
|
PROD-SVC is the name of the service the Clients will be making requests to.
|
Feign Hystrix Support
If Hystrix is on the classpath, by default Feign will wrap all methods with a circuit breaker. Returning a com.netflix.hystrix.HystrixCommand
is also available. This lets you use reactive patterns (with a call to .toObservable()
or .observe()
or asynchronous use (with a call to .queue()
).
To disable Hystrix support for Feign, set feign.hystrix.enabled=false
.
To disable Hystrix support on a per-client basis create a vanilla Feign.Builder
with the "prototype" scope, e.g.:
@Configuration
public class FooConfiguration {
@Bean
@Scope("prototype")
public Feign.Builder feignBuilder() {
return Feign.builder();
}
}
Feign Hystrix Fallbacks
Hystrix supports the notion of a fallback: a default code path that is executed when they circuit is open or there is an error. To enable fallbacks for a given @FeignClient
set the fallback
attribute to the class name that implements the fallback.
@FeignClient(name = "hello", fallback = HystrixClientFallback.class)
protected interface HystrixClient {
@RequestMapping(method = RequestMethod.GET, value = "/hello")
Hello iFailSometimes();
}
static class HystrixClientFallback implements HystrixClient {
@Override
public Hello iFailSometimes() {
return new Hello("fallback");
}
}
If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory
attribute inside @FeignClient
.
@FeignClient(name = "hello", fallbackFactory = HystrixClientFallbackFactory.class)
protected interface HystrixClient {
@RequestMapping(method = RequestMethod.GET, value = "/hello")
Hello iFailSometimes();
}
@Component
static class HystrixClientFallbackFactory implements FallbackFactory<HystrixClient> {
@Override
public HystrixClient create(Throwable cause) {
return new HystrixClientWithFallBackFactory() {
@Override
public Hello iFailSometimes() {
return new Hello("fallback; reason was: " + cause.getMessage());
}
};
}
}
Warning
|
There is a limitation with the implementation of fallbacks in Feign and how Hystrix fallbacks work. Fallbacks are currently not supported for methods that return com.netflix.hystrix.HystrixCommand and rx.Observable .
|
Feign Inheritance Support
Feign supports boilerplate apis via single-inheritance interfaces. This allows grouping common operations into convenient base interfaces.
public interface UserService {
@RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
User getUser(@PathVariable("id") long id);
}
@RestController
public class UserResource implements UserService {
}
package project.user;
@FeignClient("users")
public interface UserClient extends UserService {
}
Note
|
It is generally not advisable to share an interface between a server and a client. It introduces tight coupling, and also actually doesn’t work with Spring MVC in its current form (method parameter mapping is not inherited). |
Feign request/response compression
You may consider enabling the request or response GZIP compression for your Feign requests. You can do this by enabling one of the properties:
feign.compression.request.enabled=true
feign.compression.response.enabled=true
Feign request compression gives you settings similar to what you may set for your web server:
feign.compression.request.enabled=true
feign.compression.request.mime-types=text/xml,application/xml,application/json
feign.compression.request.min-request-size=2048
These properties allow you to be selective about the compressed media types and minimum request threshold length.
Feign logging
A logger is created for each Feign client created. By default the name of the logger is the full class name of the interface used to create the Feign client. Feign logging only responds to the DEBUG
level.
logging.level.project.user.UserClient: DEBUG
The Logger.Level
object that you may configure per client, tells Feign how much to log. Choices are:
-
NONE
, No logging (DEFAULT). -
BASIC
, Log only the request method and URL and the response status code and execution time. -
HEADERS
, Log the basic information along with request and response headers. -
FULL
, Log the headers, body, and metadata for both requests and responses.
For example, the following would set the Logger.Level
to FULL
:
@Configuration
public class FooConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
External Configuration: Archaius
Archaius is the Netflix client side configuration library. It is the library used by all of the Netflix OSS components for configuration. Archaius is an extension of the Apache Commons Configuration project. It allows updates to configuration by either polling a source for changes or for a source to push changes to the client. Archaius uses Dynamic<Type>Property classes as handles to properties.
class ArchaiusTest {
DynamicStringProperty myprop = DynamicPropertyFactory
.getInstance()
.getStringProperty("my.prop");
void doSomething() {
OtherClass.someMethod(myprop.get());
}
}
Archaius has its own set of configuration files and loading priorities. Spring applications should generally not use Archaius directly, but the need to configure the Netflix tools natively remains. Spring Cloud has a Spring Environment Bridge so Archaius can read properties from the Spring Environment. This allows Spring Boot projects to use the normal configuration toolchain, while allowing them to configure the Netflix tools, for the most part, as documented.
Router and Filter: Zuul
Routing in an integral part of a microservice architecture. For example, /
may be mapped to your web application, /api/users
is mapped to the user service and /api/shop
is mapped to the shop service. Zuul is a JVM based router and server side load balancer by Netflix.
Netflix uses Zuul for the following:
-
Authentication
-
Insights
-
Stress Testing
-
Canary Testing
-
Dynamic Routing
-
Service Migration
-
Load Shedding
-
Security
-
Static Response handling
-
Active/Active traffic management
Zuul’s rule engine allows rules and filters to be written in essentially any JVM language, with built in support for Java and Groovy.
Note
|
The configuration property zuul.max.host.connections has been replaced by two new properties, zuul.host.maxTotalConnections and zuul.host.maxPerRouteConnections which default to 200 and 20 respectively.
|
Note
|
Default Hystrix isolation pattern (ExecutionIsolationStrategy) for all routes is SEMAPHORE. zuul.ribbonIsolationStrategy can be changed to THREAD if this isolation pattern is preferred.
|
How to Include Zuul
To include Zuul in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-zuul
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Embedded Zuul Reverse Proxy
Spring Cloud has created an embedded Zuul proxy to ease the development of a very common use case where a UI application wants to proxy calls to one or more back end services. This feature is useful for a user interface to proxy to the backend services it requires, avoiding the need to manage CORS and authentication concerns independently for all the backends.
To enable it, annotate a Spring Boot main class with
@EnableZuulProxy
, and this forwards local calls to the appropriate
service. By convention, a service with the ID "users", will
receive requests from the proxy located at /users
(with the prefix
stripped). The proxy uses Ribbon to locate an instance to forward to
via discovery, and all requests are executed in a
hystrix command, so
failures will show up in Hystrix metrics, and once the circuit is open
the proxy will not try to contact the service.
Note
|
the Zuul starter does not include a discovery client, so for routes based on service IDs you need to provide one of those on the classpath as well (e.g. Eureka is one choice). |
To skip having a service automatically added, set
zuul.ignored-services
to a list of service id patterns. If a service
matches a pattern that is ignored, but also included in the explicitly
configured routes map, then it will be unignored. Example:
zuul:
ignoredServices: '*'
routes:
users: /myusers/**
In this example, all services are ignored except "users".
To augment or change the proxy routes, you can add external configuration like the following:
zuul:
routes:
users: /myusers/**
This means that http calls to "/myusers" get forwarded to the "users" service (for example "/myusers/101" is forwarded to "/101").
To get more fine-grained control over a route you can specify the path and the serviceId independently:
zuul:
routes:
users:
path: /myusers/**
serviceId: users_service
This means that http calls to "/myusers" get forwarded to the "users_service" service. The route has to have a "path" which can be specified as an ant-style pattern, so "/myusers/*" only matches one level, but "/myusers/**" matches hierarchically.
The location of the backend can be specified as either a "serviceId" (for a service from discovery) or a "url" (for a physical location), e.g.
zuul:
routes:
users:
path: /myusers/**
url: http://example.com/users_service
These simple url-routes don’t get executed as a HystrixCommand
nor can you loadbalance multiple URLs with Ribbon.
To achieve this, specify a service-route and configure a Ribbon client for the
serviceId (this currently requires disabling Eureka support in Ribbon:
see above for more information), e.g.
zuul:
routes:
users:
path: /myusers/**
serviceId: users
ribbon:
eureka:
enabled: false
users:
ribbon:
listOfServers: example.com,google.com
You can provide convention between serviceId and routes using regexmapper. It uses regular expression named groups to extract variables from serviceId and inject them into a route pattern.
@Bean
public PatternServiceRouteMapper serviceRouteMapper() {
return new PatternServiceRouteMapper(
"(?<name>^.+)-(?<version>v.+$)",
"${version}/${name}");
}
This means that a serviceId "myusers-v1" will be mapped to route "/v1/myusers/**". Any regular expression is accepted but all named groups must be present in both servicePattern and routePattern. If servicePattern does not match a serviceId, the default behavior is used. In the example above, a serviceId "myusers" will be mapped to route "/myusers/**" (no version detected) This feature is disable by default and only applies to discovered services.
To add a prefix to all mappings, set zuul.prefix
to a value, such as
/api
. The proxy prefix is stripped from the request before the
request is forwarded by default (switch this behaviour off with
zuul.stripPrefix=false
). You can also switch off the stripping of
the service-specific prefix from individual routes, e.g.
zuul:
routes:
users:
path: /myusers/**
stripPrefix: false
Note
|
zuul.stripPrefix only applies to the prefix set in zuul.prefix . It does have any effect on prefixes
defined within a given route’s path .
|
In this example, requests to "/myusers/101" will be forwarded to "/myusers/101" on the "users" service.
The zuul.routes
entries actually bind to an object of type ZuulProperties
. If you
look at the properties of that object you will see that it also has a "retryable" flag.
Set that flag to "true" to have the Ribbon client automatically retry failed requests
(and if you need to you can modify the parameters of the retry operations using
the Ribbon client configuration).
The X-Forwarded-Host
header is added to the forwarded requests by
default. To turn it off set zuul.addProxyHeaders = false
. The
prefix path is stripped by default, and the request to the backend
picks up a header "X-Forwarded-Prefix" ("/myusers" in the examples
above).
An application with @EnableZuulProxy
could act as a standalone
server if you set a default route ("/"), for example zuul.route.home:
/
would route all traffic (i.e. "/**") to the "home" service.
If more fine-grained ignoring is needed, you can specify specific patterns to ignore. These patterns are evaluated at the start of the route location process, which means prefixes should be included in the pattern to warrant a match. Ignored patterns span all services and supersede any other route specification.
zuul:
ignoredPatterns: /**/admin/**
routes:
users: /myusers/**
This means that all calls such as "/myusers/101" will be forwarded to "/101" on the "users" service. But calls including "/admin/" will not resolve.
Warning
|
If you need your routes to have their order preserved you need to use a YAML file as the ordering will be lost using a properties file. For example: |
zuul:
routes:
users:
path: /myusers/**
legacy:
path: /**
If you were to use a properties file, the legacy
path may end up in front of the users
path rendering the users
path unreachable.
Zuul Http Client
The default HTTP client used by zuul is now backed by the Apache HTTP Client instead of the
deprecated Ribbon RestClient
. To use RestClient
or to use the okhttp3.OkHttpClient
set
ribbon.restclient.enabled=true
or ribbon.okhttp.enabled=true
respectively.
Cookies and Sensitive Headers
It’s OK to share headers between services in the same system, but you probably don’t want sensitive headers leaking downstream into external servers. You can specify a list of ignored headers as part of the route configuration. Cookies play a special role because they have well-defined semantics in browsers, and they are always to be treated as sensitive. If the consumer of your proxy is a browser, then cookies for downstream services also cause problems for the user because they all get jumbled up (all downstream services look like they come from the same place).
If you are careful with the design of your services, for example if only one of the downstream services sets cookies, then you might be able to let them flow from the backend all the way up to the caller. Also, if your proxy sets cookies and all your back end services are part of the same system, it can be natural to simply share them (and for instance use Spring Session to link them up to some shared state). Other than that, any cookies that get set by downstream services are likely to be not very useful to the caller, so it is recommended that you make (at least) "Set-Cookie" and "Cookie" into sensitive headers for routes that are not part of your domain. Even for routes that are part of your domain, try to think carefully about what it means before allowing cookies to flow between them and the proxy.
The sensitive headers can be configured as a comma-separated list per route, e.g.
zuul:
routes:
users:
path: /myusers/**
sensitiveHeaders: Cookie,Set-Cookie,Authorization
url: https://downstream
Sensitive headers can also be set globally by setting zuul.sensitiveHeaders
. If sensitiveHeaders
is set on a route, this will override the global sensitiveHeaders
setting.
Note
|
this is the default value for sensitiveHeaders , so you don’t
need to set it unless you want it to be different. N.B. this is new in
Spring Cloud Netflix 1.1 (in 1.0 the user had no control over headers
and all cookies flow in both directions).
|
Ignored Headers
In addition to the per-route sensitive headers, you can set a global
value for zuul.ignoredHeaders
for values that should be discarded
(both request and response) during interactions with downstream
services. By default these are empty, if Spring Security is not on the
classpath, and otherwise they are initialized to a set of well-known
"security" headers (e.g. involving caching) as specified by Spring
Security. The assumption in this case is that the downstream services
might add these headers too, and we want the values from the proxy.
To not discard these well known security headers in case Spring Security is on the classpath you can set zuul.ignoreSecurityHeaders
to false
. This can be useful if you disabled the HTTP Security response headers in Spring Security and want the values provided by downstream services
The Routes Endpoint
If you are using @EnableZuulProxy
with tha Spring Boot Actuator you
will enable (by default) an additional endpoint, available via HTTP as
/routes
. A GET to this endpoint will return a list of the mapped
routes. A POST will force a refresh of the existing routes (e.g. in
case there have been changes in the service catalog).
Note
|
the routes should respond automatically to changes in the service catalog, but the POST to /routes is a way to force the change to happen immediately. |
Strangulation Patterns and Local Forwards
A common pattern when migrating an existing application or API is to "strangle" old endpoints, slowly replacing them with different implementations. The Zuul proxy is a useful tool for this because you can use it to handle all traffic from clients of the old endpoints, but redirect some of the requests to new ones.
Example configuration:
zuul:
routes:
first:
path: /first/**
url: http://first.example.com
second:
path: /second/**
url: forward:/second
third:
path: /third/**
url: forward:/3rd
legacy:
path: /**
url: http://legacy.example.com
In this example we are strangling the "legacy" app which is mapped to
all requests that do not match one of the other patterns. Paths in
/first/**
have been extracted into a new service with an external
URL. And paths in /second/**
are forwared so they can be handled
locally, e.g. with a normal Spring @RequestMapping
. Paths in
/third/**
are also forwarded, but with a different prefix
(i.e. /third/foo
is forwarded to /3rd/foo
).
Note
|
The ignored patterns aren’t completely ignored, they just aren’t handled by the proxy (so they are also effectively forwarded locally). |
Uploading Files through Zuul
If you @EnableZuulProxy
you can use the proxy paths to
upload files and it should just work as long as the files
are small. For large files there is an alternative path
which bypasses the Spring DispatcherServlet
(to
avoid multipart processing) in "/zuul/*". I.e. if
zuul.routes.customers=/customers/**
then you can
POST large files to "/zuul/customers/*". The servlet
path is externalized via zuul.servletPath
. Extremely
large files will also require elevated timeout settings
if the proxy route takes you through a Ribbon load
balancer, e.g.
hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds: 60000
ribbon:
ConnectTimeout: 3000
ReadTimeout: 60000
Note that for streaming to work with large files, you need to use chunked encoding in the request (which some browsers do not do by default). E.g. on the command line:
$ curl -v -H "Transfer-Encoding: chunked" \ -F "[email protected]" localhost:9999/zuul/simple/file
Plain Embedded Zuul
You can also run a Zuul server without the proxying, or switch on parts of the proxying platform selectively, if you
use @EnableZuulServer
(instead of @EnableZuulProxy
). Any beans that you add to the application of type ZuulFilter
will be installed automatically, as they are with @EnableZuulProxy
, but without any of the proxy filters being added
automatically.
In this case the routes into the Zuul server are still specified by configuring "zuul.routes.*", but there is no service discovery and no proxying, so the "serviceId" and "url" settings are ignored. For example:
zuul:
routes:
api: /api/**
maps all paths in "/api/**" to the Zuul filter chain.
Disable Zuul Filters
Zuul for Spring Cloud comes with a number of ZuulFilter
beans enabled by default
in both proxy and server mode. See the zuul filters package for the
possible filters that are enabled. If you want to disable one, simply set
zuul.<SimpleClassName>.<filterType>.disable=true
. By convention, the package after
filters
is the Zuul filter type. For example to disable
org.springframework.cloud.netflix.zuul.filters.post.SendResponseFilter
set
zuul.SendResponseFilter.post.disable=true
.
Providing Hystrix Fallbacks For Routes
When a circuit for a given route in Zuul is tripped you can provide a fallback response
by creating a bean of type ZuulFallbackProvider
. Within this bean you need to specify
the route ID the fallback is for and provide a ClientHttpResponse
to return
as a fallback. Here is a very simple ZuulFallbackProvider
implementation.
class MyFallbackProvider implements ZuulFallbackProvider {
@Override
public String getRoute() {
return "customers";
}
@Override
public ClientHttpResponse fallbackResponse() {
return new ClientHttpResponse() {
@Override
public HttpStatus getStatusCode() throws IOException {
return HttpStatus.OK;
}
@Override
public int getRawStatusCode() throws IOException {
return 200;
}
@Override
public String getStatusText() throws IOException {
return "OK";
}
@Override
public void close() {
}
@Override
public InputStream getBody() throws IOException {
return new ByteArrayInputStream("fallback".getBytes());
}
@Override
public HttpHeaders getHeaders() {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
return headers;
}
};
}
}
And here is what the route configuration would look like.
zuul:
routes:
customers: /customers/**
Polyglot support with Sidecar
Do you have non-jvm languages you want to take advantage of Eureka, Ribbon and Config Server? The Spring Cloud Netflix Sidecar was inspired by Netflix Prana. It includes a simple http api to get all of the instances (ie host and port) for a given service. You can also proxy service calls through an embedded Zuul proxy which gets its route entries from Eureka. The Spring Cloud Config Server can be accessed directly via host lookup or through the Zuul Proxy. The non-jvm app should implement a health check so the Sidecar can report to eureka if the app is up or down.
To include Sidecar in your project use the dependency with group org.springframework.cloud
and artifact id spring-cloud-netflix-sidecar
.
To enable the Sidecar, create a Spring Boot application with @EnableSidecar
.
This annotation includes @EnableCircuitBreaker
, @EnableDiscoveryClient
,
and @EnableZuulProxy
. Run the resulting application on the same host as the
non-jvm application.
To configure the side car add sidecar.port
and sidecar.health-uri
to application.yml
.
The sidecar.port
property is the port the non-jvm app is listening on. This
is so the Sidecar can properly register the app with Eureka. The sidecar.health-uri
is a uri accessible on the non-jvm app that mimicks a Spring Boot health
indicator. It should return a json document like the following:
{
"status":"UP"
}
Here is an example application.yml for a Sidecar application:
server:
port: 5678
spring:
application:
name: sidecar
sidecar:
port: 8000
health-uri: http://localhost:8000/health.json
The api for the DiscoveryClient.getInstances()
method is /hosts/{serviceId}
.
Here is an example response for /hosts/customers
that returns two instances on
different hosts. This api is accessible to the non-jvm app (if the sidecar is
on port 5678) at http://localhost:5678/hosts/{serviceId}
.
[
{
"host": "myhost",
"port": 9000,
"uri": "http://myhost:9000",
"serviceId": "CUSTOMERS",
"secure": false
},
{
"host": "myhost2",
"port": 9000,
"uri": "http://myhost2:9000",
"serviceId": "CUSTOMERS",
"secure": false
}
]
The Zuul proxy automatically adds routes for each service known in eureka to
/<serviceId>
, so the customers service is available at /customers
. The
Non-jvm app can access the customer service via http://localhost:5678/customers
(assuming the sidecar is listening on port 5678).
If the Config Server is registered with Eureka, non-jvm application can access
it via the Zuul proxy. If the serviceId of the ConfigServer is configserver
and the Sidecar is on port 5678, then it can be accessed at
http://localhost:5678/configserver
Non-jvm app can take advantage of the Config Server’s ability to return YAML documents. For example, a call to http://sidecar.local.spring.io:5678/configserver/default-master.yml might result in a YAML document like the following
eureka:
client:
serviceUrl:
defaultZone: http://localhost:8761/eureka/
password: password
info:
description: Spring Cloud Samples
url: https://github.com/spring-cloud-samples
RxJava with Spring MVC
Spring Cloud Netflix includes the RxJava.
RxJava is a Java VM implementation of Reactive Extensions: a library for composing asynchronous and event-based programs by using observable sequences.
Spring Cloud Netflix provides support for returning rx.Single
objects from Spring MVC Controllers. It also supports using rx.Observable
objects for Server-sent events (SSE). This can be very convenient if your internal APIs are already built using RxJava (see Feign Hystrix Support for examples).
Here are some examples of using rx.Single
:
@RequestMapping(method = RequestMethod.GET, value = "/single")
public Single<String> single() {
return Single.just("single value");
}
@RequestMapping(method = RequestMethod.GET, value = "/singleWithResponse")
public ResponseEntity<Single<String>> singleWithResponse() {
return new ResponseEntity<>(Single.just("single value"),
HttpStatus.NOT_FOUND);
}
@RequestMapping(method = RequestMethod.GET, value = "/singleCreatedWithResponse")
public Single<ResponseEntity<String>> singleOuterWithResponse() {
return Single.just(new ResponseEntity<>("single value", HttpStatus.CREATED));
}
@RequestMapping(method = RequestMethod.GET, value = "/throw")
public Single<Object> error() {
return Single.error(new RuntimeException("Unexpected"));
}
If you have an Observable
, rather than a single, you can use .toSingle()
or .toList().toSingle()
. Here are some examples:
@RequestMapping(method = RequestMethod.GET, value = "/single")
public Single<String> single() {
return Observable.just("single value").toSingle();
}
@RequestMapping(method = RequestMethod.GET, value = "/multiple")
public Single<List<String>> multiple() {
return Observable.just("multiple", "values").toList().toSingle();
}
@RequestMapping(method = RequestMethod.GET, value = "/responseWithObservable")
public ResponseEntity<Single<String>> responseWithObservable() {
Observable<String> observable = Observable.just("single value");
HttpHeaders headers = new HttpHeaders();
headers.setContentType(APPLICATION_JSON_UTF8);
return new ResponseEntity<>(observable.toSingle(), headers, HttpStatus.CREATED);
}
@RequestMapping(method = RequestMethod.GET, value = "/timeout")
public Observable<String> timeout() {
return Observable.timer(1, TimeUnit.MINUTES).map(new Func1<Long, String>() {
@Override
public String call(Long aLong) {
return "single value";
}
});
}
If you have a streaming endpoint and client, SSE could be an option. To convert rx.Observable
to a Spring SseEmitter
use RxResponse.sse()
. Here are some examples:
@RequestMapping(method = RequestMethod.GET, value = "/sse")
public SseEmitter single() {
return RxResponse.sse(Observable.just("single value"));
}
@RequestMapping(method = RequestMethod.GET, value = "/messages")
public SseEmitter messages() {
return RxResponse.sse(Observable.just("message 1", "message 2", "message 3"));
}
@RequestMapping(method = RequestMethod.GET, value = "/events")
public SseEmitter event() {
return RxResponse.sse(APPLICATION_JSON_UTF8,
Observable.just(new EventDto("Spring io", getDate(2016, 5, 19)),
new EventDto("SpringOnePlatform", getDate(2016, 8, 1))));
}
Metrics: Spectator, Servo, and Atlas
When used together, Spectator/Servo and Atlas provide a near real-time operational insight platform.
Spectator and Servo are Netflix’s metrics collection libraries. Atlas is a Netflix metrics backend to manage dimensional time series data.
Servo served Netflix for several years and is still usable, but is gradually being phased out in favor of Spectator, which is only designed to work with Java 8. Spring Cloud Netflix provides support for both, but Java 8 based applications are encouraged to use Spectator.
Dimensional vs. Hierarchical Metrics
Spring Boot Actuator metrics are hierarchical and metrics are separated only by name. These names often follow a naming convention that embeds key/value attribute pairs (dimensions) into the name separated by periods. Consider the following metrics for two endpoints, root and star-star:
{
"counter.status.200.root": 20,
"counter.status.400.root": 3,
"counter.status.200.star-star": 5,
}
The first metric gives us a normalized count of successful requests against the root endpoint per unit of time. But what if the system had 20 endpoints and you want to get a count of successful requests against all the endpoints? Some hierarchical metrics backends would allow you to specify a wild card such as counter.status.200.
that would read all 20 metrics and aggregate the results. Alternatively, you could provide a HandlerInterceptorAdapter
that intercepts and records a metric like counter.status.200.all
for all successful requests irrespective of the endpoint, but now you must write 20+1 different metrics. Similarly if you want to know the total number of successful requests for all endpoints in the service, you could specify a wild card such as counter.status.2.*
.
Even in the presence of wildcarding support on a hierarchical metrics backend, naming consistency can be difficult. Specifically the position of these tags in the name string can slip with time, breaking queries. For example, suppose we add an additional dimension to the hierarchical metrics above for HTTP method. Then counter.status.200.root
becomes counter.status.200.method.get.root
, etc. Our counter.status.200.*
suddenly no longer has the same semantic meaning. Furthermore, if the new dimension is not applied uniformly across the codebase, certain queries may become impossible. This can quickly get out of hand.
Netflix metrics are tagged (a.k.a. dimensional). Each metric has a name, but this single named metric can contain multiple statistics and 'tag' key/value pairs that allows more querying flexibility. In fact, the statistics themselves are recorded in a special tag.
Recorded with Netflix Servo or Spectator, a timer for the root endpoint described above contains 4 statistics per status code, where the count statistic is identical to Spring Boot Actuator’s counter. In the event that we have encountered an HTTP 200 and 400 thus far, there will be 8 available data points:
{
"root(status=200,stastic=count)": 20,
"root(status=200,stastic=max)": 0.7265630630000001,
"root(status=200,stastic=totalOfSquares)": 0.04759702862580789,
"root(status=200,stastic=totalTime)": 0.2093076914666667,
"root(status=400,stastic=count)": 1,
"root(status=400,stastic=max)": 0,
"root(status=400,stastic=totalOfSquares)": 0,
"root(status=400,stastic=totalTime)": 0,
}
Default Metrics Collection
Without any additional dependencies or configuration, a Spring Cloud based service will autoconfigure a Servo MonitorRegistry
and begin collecting metrics on every Spring MVC request. By default, a Servo timer with the name rest
will be recorded for each MVC request which is tagged with:
-
HTTP method
-
HTTP status (e.g. 200, 400, 500)
-
URI (or "root" if the URI is empty), sanitized for Atlas
-
The exception class name, if the request handler threw an exception
-
The caller, if a request header with a key matching
netflix.metrics.rest.callerHeader
is set on the request. There is no default key fornetflix.metrics.rest.callerHeader
. You must add it to your application properties if you wish to collect caller information.
Set the netflix.metrics.rest.metricName
property to change the name of the metric from rest
to a name you provide.
If Spring AOP is enabled and org.aspectj:aspectjweaver
is present on your runtime classpath, Spring Cloud will also collect metrics on every client call made with RestTemplate
. A Servo timer with the name of restclient
will be recorded for each MVC request which is tagged with:
-
HTTP method
-
HTTP status (e.g. 200, 400, 500), "CLIENT_ERROR" if the response returned null, or "IO_ERROR" if an
IOException
occurred during the execution of theRestTemplate
method -
URI, sanitized for Atlas
-
Client name
Warning
|
Avoid using hardcoded url parameters within RestTemplate . When targeting dynamic endpoints use URL variables. This will avoid potential "GC Overhead Limit Reached" issues where ServoMonitorCache treats each url as a unique key.
|
// recommended
String orderid = "1";
restTemplate.getForObject("http://testeurekabrixtonclient/orders/{orderid}", String.class, orderid)
// avoid
restTemplate.getForObject("http://testeurekabrixtonclient/orders/1", String.class)
Metrics Collection: Spectator
To enable Spectator metrics, include a dependency on spring-boot-starter-spectator
:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-spectator</artifactId>
</dependency>
In Spectator parlance, a meter is a named, typed, and tagged configuration and a metric represents the value of a given meter at a point in time. Spectator meters are created and controlled by a registry, which currently has several different implementations. Spectator provides 4 meter types: counter, timer, gauge, and distribution summary.
Spring Cloud Spectator integration configures an injectable com.netflix.spectator.api.Registry
instance for you. Specifically, it configures a ServoRegistry
instance in order to unify the collection of REST metrics and the exporting of metrics to the Atlas backend under a single Servo API. Practically, this means that your code may use a mixture of Servo monitors and Spectator meters and both will be scooped up by Spring Boot Actuator MetricReader
instances and both will be shipped to the Atlas backend.
Spectator Counter
A counter is used to measure the rate at which some event is occurring.
// create a counter with a name and a set of tags
Counter counter = registry.counter("counterName", "tagKey1", "tagValue1", ...);
counter.increment(); // increment when an event occurs
counter.increment(10); // increment by a discrete amount
The counter records a single time-normalized statistic.
Spectator Timer
A timer is used to measure how long some event is taking. Spring Cloud automatically records timers for Spring MVC requests and conditionally RestTemplate
requests, which can later be used to create dashboards for request related metrics like latency:
image::RequestLatency.png []
// create a timer with a name and a set of tags
Timer timer = registry.timer("timerName", "tagKey1", "tagValue1", ...);
// execute an operation and time it at the same time
T result = timer.record(() -> fooReturnsT());
// alternatively, if you must manually record the time
Long start = System.nanoTime();
T result = fooReturnsT();
timer.record(System.nanoTime() - start, TimeUnit.NANOSECONDS);
The timer simultaneously records 4 statistics: count, max, totalOfSquares, and totalTime. The count statistic will always match the single normalized value provided by a counter if you had called increment()
once on the counter for each time you recorded a timing, so it is rarely necessary to count and time separately for a single operation.
For long running operations, Spectator provides a special LongTaskTimer
.
Spectator Gauge
Gauges are used to determine some current value like the size of a queue or number of threads in a running state. Since gauges are sampled, they provide no information about how these values fluctuate between samples.
The normal use of a gauge involves registering the gauge once in initialization with an id, a reference to the object to be sampled, and a function to get or compute a numeric value based on the object. The reference to the object is passed in separately and the Spectator registry will keep a weak reference to the object. If the object is garbage collected, then Spectator will automatically drop the registration. See the note in Spectator’s documentation about potential memory leaks if this API is misused.
// the registry will automatically sample this gauge periodically
registry.gauge("gaugeName", pool, Pool::numberOfRunningThreads);
// manually sample a value in code at periodic intervals -- last resort!
registry.gauge("gaugeName", Arrays.asList("tagKey1", "tagValue1", ...), 1000);
Spectator Distribution Summaries
A distribution summary is used to track the distribution of events. It is similar to a timer, but more general in that the size does not have to be a period of time. For example, a distribution summary could be used to measure the payload sizes of requests hitting a server.
// the registry will automatically sample this gauge periodically
DistributionSummary ds = registry.distributionSummary("dsName", "tagKey1", "tagValue1", ...);
ds.record(request.sizeInBytes());
Metrics Collection: Servo
Warning
|
If your code is compiled on Java 8, please use Spectator instead of Servo as Spectator is destined to replace Servo entirely in the long term. |
In Servo parlance, a monitor is a named, typed, and tagged configuration and a metric represents the value of a given monitor at a point in time. Servo monitors are logically equivalent to Spectator meters. Servo monitors are created and controlled by a MonitorRegistry
. In spite of the above warning, Servo does have a wider array of monitor options than Spectator has meters.
Spring Cloud integration configures an injectable com.netflix.servo.MonitorRegistry
instance for you. Once you have created the appropriate Monitor
type in Servo, the process of recording data is wholly similar to Spectator.
Creating Servo Monitors
If you are using the Servo MonitorRegistry
instance provided by Spring Cloud (specifically, an instance of DefaultMonitorRegistry
), Servo provides convenience classes for retrieving counters and timers. These convenience classes ensure that only one Monitor
is registered for each unique combination of name and tags.
To manually create a Monitor type in Servo, especially for the more exotic monitor types for which convenience methods are not provided, instantiate the appropriate type by providing a MonitorConfig
instance:
MonitorConfig config = MonitorConfig.builder("timerName").withTag("tagKey1", "tagValue1").build();
// somewhere we should cache this Monitor by MonitorConfig
Timer timer = new BasicTimer(config);
monitorRegistry.register(timer);
Metrics Backend: Atlas
Atlas was developed by Netflix to manage dimensional time series data for near real-time operational insight. Atlas features in-memory data storage, allowing it to gather and report very large numbers of metrics, very quickly.
Atlas captures operational intelligence. Whereas business intelligence is data gathered for analyzing trends over time, operational intelligence provides a picture of what is currently happening within a system.
Spring Cloud provides a spring-cloud-starter-atlas
that has all the dependencies you need. Then just annotate your Spring Boot application with @EnableAtlas
and provide a location for your running Atlas server with the netflix.atlas.uri
property.
Global tags
Spring Cloud enables you to add tags to every metric sent to the Atlas backend. Global tags can be used to separate metrics by application name, environment, region, etc.
Each bean implementing AtlasTagProvider
will contribute to the global tag list:
@Bean
AtlasTagProvider atlasCommonTags(
@Value("${spring.application.name}") String appName) {
return () -> Collections.singletonMap("app", appName);
}
Using Atlas
To bootstrap a in-memory standalone Atlas instance:
$ curl -LO https://github.com/Netflix/atlas/releases/download/v1.4.2/atlas-1.4.2-standalone.jar
$ java -jar atlas-1.4.2-standalone.jar
Tip
|
An Atlas standalone node running on an r3.2xlarge (61GB RAM) can handle roughly 2 million metrics per minute for a given 6 hour window. |
Once running and you have collected a handful of metrics, verify that your setup is correct by listing tags on the Atlas server:
$ curl http://ATLAS/api/v1/tags
Tip
|
After executing several requests against your service, you can gather some very basic information on the request latency of every request by pasting the following url in your browser: http://ATLAS/api/v1/graph?q=name,rest,:eq,:avg
|
The Atlas wiki contains a compilation of sample queries for various scenarios.
Make sure to check out the alerting philosophy and docs on using double exponential smoothing to generate dynamic alert thresholds.
Retrying Failed Requests
Spring Cloud Netflix offers a variety of ways to make HTTP requests. You can use a load balanced
RestTemplate
, Ribbon, or Feign. No matter how you choose to your HTTP requests, there is always
a chance the request may fail. When a request fails you may want to have the request retried
automatically. To accomplish this when using Sping Cloud Netflix you need to include
Spring Retry on your application’s classpath.
When Spring Retry is present load balanced RestTemplates
, Feign, and Zuul will automatically
retry any failed requests (assuming you configuration allows it to).
Configuration
Anytime Ribbon is used with Spring Retry you can control the retry functionality by configuring
certain Ribbon properties. The properties you can use are
client.ribbon.MaxAutoRetries
, client.ribbon.MaxAutoRetriesNextServer
, and
client.ribbon.OkToRetryOnAllOperations
. See the Ribbon documentation
for a description of what there properties do.
Zuul
You can turn off Zuul’s retry functionality by setting zuul.retryable
to false
. You
can also disable retry functionality on route by route basis by setting
zuul.routes.routename.retryable
to false
.
Spring Cloud Stream
Spring Cloud Stream Reference Guide
Spring Cloud Stream Core
This section goes into more detail about how you can work with Spring Cloud Stream. It covers topics such as creating and running stream applications.
Introducing Spring Cloud Stream
Spring Cloud Stream is a framework for building message-driven microservice applications. Spring Cloud Stream builds upon Spring Boot to create standalone, production-grade Spring applications, and uses Spring Integration to provide connectivity to message brokers. It provides opinionated configuration of middleware from several vendors, introducing the concepts of persistent publish-subscribe semantics, consumer groups, and partitions.
You can add the @EnableBinding
annotation to your application to get immediate connectivity to a message broker, and you can add @StreamListener
to a method to cause it to receive events for stream processing.
The following is a simple sink application which receives external messages.
@SpringBootApplication
@EnableBinding(Sink.class)
public class VoteRecordingSinkApplication {
public static void main(String[] args) {
SpringApplication.run(VoteRecordingSinkApplication.class, args);
}
@StreamListener(Sink.INPUT)
public void processVote(Vote vote) {
votingService.recordVote(vote);
}
}
The @EnableBinding
annotation takes one or more interfaces as parameters (in this case, the parameter is a single Sink
interface).
An interface declares input and/or output channels.
Spring Cloud Stream provides the interfaces Source
, Sink
, and Processor
; you can also define your own interfaces.
The following is the definition of the Sink
interface:
public interface Sink {
String INPUT = "input";
@Input(Sink.INPUT)
SubscribableChannel input();
}
The @Input
annotation identifies an input channel, through which received messages enter the application; the @Output
annotation identifies an output channel, through which published messages leave the application.
The @Input
and @Output
annotations can take a channel name as a parameter; if a name is not provided, the name of the annotated method will be used.
Spring Cloud Stream will create an implementation of the interface for you. You can use this in the application by autowiring it, as in the following example of a test case.
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = VoteRecordingSinkApplication.class)
@WebAppConfiguration
@DirtiesContext
public class StreamApplicationTests {
@Autowired
private Sink sink;
@Test
public void contextLoads() {
assertNotNull(this.sink.input());
}
}
Main Concepts
Spring Cloud Stream provides a number of abstractions and primitives that simplify the writing of message-driven microservice applications. This section gives an overview of the following:
-
Spring Cloud Stream’s application model
-
The Binder abstraction
-
Persistent publish-subscribe support
-
Consumer group support
-
Partitioning support
-
A pluggable Binder API
Application Model
A Spring Cloud Stream application consists of a middleware-neutral core. The application communicates with the outside world through input and output channels injected into it by Spring Cloud Stream. Channels are connected to external brokers through middleware-specific Binder implementations.
Fat JAR
Spring Cloud Stream applications can be run in standalone mode from your IDE for testing. To run a Spring Cloud Stream application in production, you can create an executable (or "fat") JAR by using the standard Spring Boot tooling provided for Maven or Gradle.
The Binder Abstraction
Spring Cloud Stream provides Binder implementations for Kafka and Rabbit MQ. Spring Cloud Stream also includes a TestSupportBinder, which leaves a channel unmodified so that tests can interact with channels directly and reliably assert on what is received. You can use the extensible API to write your own Binder.
Spring Cloud Stream uses Spring Boot for configuration, and the Binder abstraction makes it possible for a Spring Cloud Stream application to be flexible in how it connects to middleware.
For example, deployers can dynamically choose, at runtime, the destinations (e.g., the Kafka topics or RabbitMQ exchanges) to which channels connect.
Such configuration can be provided through external configuration properties and in any form supported by Spring Boot (including application arguments, environment variables, and application.yml
or application.properties
files).
In the sink example from the Introducing Spring Cloud Stream section, setting the application property spring.cloud.stream.bindings.input.destination
to raw-sensor-data
will cause it to read from the raw-sensor-data
Kafka topic, or from a queue bound to the raw-sensor-data
RabbitMQ exchange.
Spring Cloud Stream automatically detects and uses a binder found on the classpath. You can easily use different types of middleware with the same code: just include a different binder at build time. For more complex use cases, you can also package multiple binders with your application and have it choose the binder, and even whether to use different binders for different channels, at runtime.
Persistent Publish-Subscribe Support
Communication between applications follows a publish-subscribe model, where data is broadcast through shared topics. This can be seen in the following figure, which shows a typical deployment for a set of interacting Spring Cloud Stream applications.
Data reported by sensors to an HTTP endpoint is sent to a common destination named raw-sensor-data
.
From the destination, it is independently processed by a microservice application that computes time-windowed averages and by another microservice application that ingests the raw data into HDFS.
In order to process the data, both applications declare the topic as their input at runtime.
The publish-subscribe communication model reduces the complexity of both the producer and the consumer, and allows new applications to be added to the topology without disruption of the existing flow. For example, downstream from the average-calculating application, you can add an application that calculates the highest temperature values for display and monitoring. You can then add another application that interprets the same flow of averages for fault detection. Doing all communication through shared topics rather than point-to-point queues reduces coupling between microservices.
While the concept of publish-subscribe messaging is not new, Spring Cloud Stream takes the extra step of making it an opinionated choice for its application model. By using native middleware support, Spring Cloud Stream also simplifies use of the publish-subscribe model across different platforms.
Consumer Groups
While the publish-subscribe model makes it easy to connect applications through shared topics, the ability to scale up by creating multiple instances of a given application is equally important. When doing this, different instances of an application are placed in a competing consumer relationship, where only one of the instances is expected to handle a given message.
Spring Cloud Stream models this behavior through the concept of a consumer group.
(Spring Cloud Stream consumer groups are similar to and inspired by Kafka consumer groups.)
Each consumer binding can use the spring.cloud.stream.bindings.<channelName>.group
property to specify a group name.
For the consumers shown in the following figure, this property would be set as spring.cloud.stream.bindings.<channelName>.group=hdfsWrite
or spring.cloud.stream.bindings.<channelName>.group=average
.
All groups which subscribe to a given destination receive a copy of published data, but only one member of each group receives a given message from that destination. By default, when a group is not specified, Spring Cloud Stream assigns the application to an anonymous and independent single-member consumer group that is in a publish-subscribe relationship with all other consumer groups.
Durability
Consistent with the opinionated application model of Spring Cloud Stream, consumer group subscriptions are durable. That is, a binder implementation ensures that group subscriptions are persistent, and once at least one subscription for a group has been created, the group will receive messages, even if they are sent while all applications in the group are stopped.
Note
|
Anonymous subscriptions are non-durable by nature. For some binder implementations (e.g., RabbitMQ), it is possible to have non-durable group subscriptions. |
In general, it is preferable to always specify a consumer group when binding an application to a given destination. When scaling up a Spring Cloud Stream application, you must specify a consumer group for each of its input bindings. This prevents the application’s instances from receiving duplicate messages (unless that behavior is desired, which is unusual).
Partitioning Support
Spring Cloud Stream provides support for partitioning data between multiple instances of a given application. In a partitioned scenario, the physical communication medium (e.g., the broker topic) is viewed as being structured into multiple partitions. One or more producer application instances send data to multiple consumer application instances and ensure that data identified by common characteristics are processed by the same consumer instance.
Spring Cloud Stream provides a common abstraction for implementing partitioned processing use cases in a uniform fashion. Partitioning can thus be used whether the broker itself is naturally partitioned (e.g., Kafka) or not (e.g., RabbitMQ).
Partitioning is a critical concept in stateful processing, where it is critiical, for either performance or consistency reasons, to ensure that all related data is processed together. For example, in the time-windowed average calculation example, it is important that all measurements from any given sensor are processed by the same application instance.
Note
|
To set up a partitioned processing scenario, you must configure both the data-producing and the data-consuming ends. |
Programming Model
This section describes Spring Cloud Stream’s programming model. Spring Cloud Stream provides a number of predefined annotations for declaring bound input and output channels as well as how to listen to channels.
Declaring and Binding Channels
Triggering Binding Via @EnableBinding
You can turn a Spring application into a Spring Cloud Stream application by applying the @EnableBinding
annotation to one of the application’s configuration classes.
The @EnableBinding
annotation itself is meta-annotated with @Configuration
and triggers the configuration of Spring Cloud Stream infrastructure:
...
@Import(...)
@Configuration
@EnableIntegration
public @interface EnableBinding {
...
Class<?>[] value() default {};
}
The @EnableBinding
annotation can take as parameters one or more interface classes that contain methods which represent bindable components (typically message channels).
Note
|
In Spring Cloud Stream 1.0, the only supported bindable components are the Spring Messaging |
@Input
and @Output
A Spring Cloud Stream application can have an arbitrary number of input and output channels defined in an interface as @Input
and @Output
methods:
public interface Barista {
@Input
SubscribableChannel orders();
@Output
MessageChannel hotDrinks();
@Output
MessageChannel coldDrinks();
}
Using this interface as a parameter to @EnableBinding
will trigger the creation of three bound channels named orders
, hotDrinks
, and coldDrinks
, respectively.
@EnableBinding(Barista.class)
public class CafeConfiguration {
...
}
Customizing Channel Names
Using the @Input
and @Output
annotations, you can specify a customized channel name for the channel, as shown in the following example:
public interface Barista {
...
@Input("inboundOrders")
SubscribableChannel orders();
}
In this example, the created bound channel will be named inboundOrders
.
Source
, Sink
, and Processor
For easy addressing of the most common use cases, which involve either an input channel, an output channel, or both, Spring Cloud Stream provides three predefined interfaces out of the box.
Source
can be used for an application which has a single outbound channel.
public interface Source {
String OUTPUT = "output";
@Output(Source.OUTPUT)
MessageChannel output();
}
Sink
can be used for an application which has a single inbound channel.
public interface Sink {
String INPUT = "input";
@Input(Sink.INPUT)
SubscribableChannel input();
}
Processor
can be used for an application which has both an inbound channel and an outbound channel.
public interface Processor extends Source, Sink {
}
Spring Cloud Stream provides no special handling for any of these interfaces; they are only provided out of the box.
Accessing Bound Channels
Injecting the Bound Interfaces
For each bound interface, Spring Cloud Stream will generate a bean that implements the interface.
Invoking a @Input
-annotated or @Output
-annotated method of one of these beans will return the relevant bound channel.
The bean in the following example sends a message on the output channel when its hello
method is invoked.
It invokes output()
on the injected Source
bean to retrieve the target channel.
@Component
public class SendingBean {
private Source source;
@Autowired
public SendingBean(Source source) {
this.source = source;
}
public void sayHello(String name) {
source.output().send(MessageBuilder.withPayload(name).build());
}
}
Injecting Channels Directly
Bound channels can be also injected directly:
@Component
public class SendingBean {
private MessageChannel output;
@Autowired
public SendingBean(MessageChannel output) {
this.output = output;
}
public void sayHello(String name) {
output.send(MessageBuilder.withPayload(name).build());
}
}
If the name of the channel is customized on the declaring annotation, that name should be used instead of the method name. Given the following declaration:
public interface CustomSource {
...
@Output("customOutput")
MessageChannel output();
}
The channel will be injected as shown in the following example:
@Component
public class SendingBean {
@Autowired @Qualifier("customOutput")
private MessageChannel output;
@Autowired
public SendingBean(MessageChannel output) {
this.output = output;
}
public void sayHello(String name) {
this.output.send(MessageBuilder.withPayload(name).build());
}
}
Producing and Consuming Messages
You can write a Spring Cloud Stream application using either Spring Integration annotations or Spring Cloud Stream’s @StreamListener
annotation.
The @StreamListener
annotation is modeled after other Spring Messaging annotations (such as @MessageMapping
, @JmsListener
, @RabbitListener
, etc.) but adds content type management and type coercion features.
Native Spring Integration Support
Because Spring Cloud Stream is based on Spring Integration, Stream completely inherits Integration’s foundation and infrastructure as well as the component itself.
For example, you can attach the output channel of a Source
to a MessageSource
:
@EnableBinding(Source.class)
public class TimerSource {
@Value("${format}")
private String format;
@Bean
@InboundChannelAdapter(value = Source.OUTPUT, poller = @Poller(fixedDelay = "${fixedDelay}", maxMessagesPerPoll = "1"))
public MessageSource<String> timerMessageSource() {
return () -> new GenericMessage<>(new SimpleDateFormat(format).format(new Date()));
}
}
Or you can use a processor’s channels in a transformer:
@EnableBinding(Processor.class)
public class TransformProcessor {
@Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
public Object transform(String message) {
return message.toUpper();
}
}
Using @StreamListener for Automatic Content Type Handling
Complementary to its Spring Integration support, Spring Cloud Stream provides its own @StreamListener
annotation, modeled after other Spring Messaging annotations (e.g. @MessageMapping
, @JmsListener
, @RabbitListener
, etc.).
The @StreamListener
annotation provides a simpler model for handling inbound messages, especially when dealing with use cases that involve content type management and type coercion.
Spring Cloud Stream provides an extensible MessageConverter
mechanism for handling data conversion by bound channels and for, in this case, dispatching to methods annotated with @StreamListener
.
The following is an example of an application which processes external Vote
events:
@EnableBinding(Sink.class)
public class VoteHandler {
@Autowired
VotingService votingService;
@StreamListener(Sink.INPUT)
public void handle(Vote vote) {
votingService.record(vote);
}
}
The distinction between @StreamListener
and a Spring Integration @ServiceActivator
is seen when considering an inbound Message
that has a String
payload and a contentType
header of application/json
.
In the case of @StreamListener
, the MessageConverter
mechanism will use the contentType
header to parse the String
payload into a Vote
object.
As with other Spring Messaging methods, method arguments can be annotated with @Payload
, @Headers
and @Header
.
Note
|
For methods which return data, you must use the
|
Reactive Programming Support
Spring Cloud Stream also supports the use of reactive APIs where incoming and outgoing data is handled as continuous data flows.
Support for reactive APIs is available via the spring-cloud-stream-reactive
, which needs to be added explicitly to your project.
The programming model with reactive APIs is declarative, where instead of specifying how each individual message should be handled, you can use operators that describe functional transformations from inbound to outbound data flows.
Spring Cloud Stream supports the following reactive APIs:
-
Reactor
-
RxJava 1.x
In the future, it is intended to support a more generic model based on Reactive Streams.
The reactive programming model is also using the @StreamListener
annotation for setting up reactive handlers. The differences are that:
-
the
@StreamListener
annotation must not specify an input or output, as they are provided as arguments and return values from the method; -
the arguments of the method must be annotated with
@Input
and@Output
indicating which input or output will the incoming and respectively outgoing data flows connect to; -
the return value of the method, if any, will be annotated with
@Output
, indicating the input where data shall be sent.
Note
|
Reactive programming support requires Java 1.8. |
Note
|
As of Spring Cloud Stream 1.1.1 and later (starting with release train Brooklyn.SR2), reactive programming support requires the use of Reactor 3.0.4.RELEASE and higher.
Earlier Reactor versions (including 3.0.1.RELEASE, 3.0.2.RELEASE and 3.0.3.RELEASE) are not supported.
|
Note
|
The use of term |
Reactor-based handlers
A Reactor based handler can have the following argument types:
-
For arguments annotated with
@Input
, it supports the Reactor typeFlux
. The parameterization of the inbound Flux follows the same rules as in the case of individual message handling: it can be the entireMessage
, a POJO which can be theMessage
payload, or a POJO which is the result of a transformation based on theMessage
content-type header. Multiple inputs are provided; -
For arguments annotated with
Output
, it supports the typeFluxSender
which connects aFlux
produced by the method with an output. Generally speaking, specifying outputs as arguments is only recommended when the method can have multiple outputs;
A Reactor based handler supports a return type of Flux
, case in which it must be annotated with @Output
. We recommend using the return value of the method when a single output flux is available.
Here is an example of a simple Reactor-based Processor.
@EnableBinding(Processor.class)
@EnableAutoConfiguration
public static class UppercaseTransformer {
@StreamListener
@Output(Processor.OUTPUT)
public Flux<String> receive(@Input(Processor.INPUT) Flux<String> input) {
return input.map(s -> s.toUpperCase());
}
}
The same processor using output arguments looks like this:
@EnableBinding(Processor.class)
@EnableAutoConfiguration
public static class UppercaseTransformer {
@StreamListener
public void receive(@Input(Processor.INPUT) Flux<String> input,
@Output(Processor.OUTPUT) FluxSender output) {
output.send(input.map(s -> s.toUpperCase()));
}
}
RxJava 1.x support
RxJava 1.x handlers follow the same rules as Reactor-based one, but will use Observable
and ObservableSender
arguments and return types.
So the first example above will become:
@EnableBinding(Processor.class)
@EnableAutoConfiguration
public static class UppercaseTransformer {
@StreamListener
@Output(Processor.OUTPUT)
public Observable<String> receive(@Input(Processor.INPUT) Observable<String> input) {
return input.map(s -> s.toUpperCase());
}
}
The second example above will become:
@EnableBinding(Processor.class)
@EnableAutoConfiguration
public static class UppercaseTransformer {
@StreamListener
public void receive(@Input(Processor.INPUT) Observable<String> input,
@Output(Processor.OUTPUT) ObservableSender output) {
output.send(input.map(s -> s.toUpperCase()));
}
}
Aggregation
Spring Cloud Stream provides support for aggregating multiple applications together, connecting their input and output channels directly and avoiding the additional cost of exchanging messages via a broker. As of version 1.0 of Spring Cloud Stream, aggregation is supported only for the following types of applications:
-
sources - applications with a single output channel named
output
, typically having a single binding of the typeorg.springframework.cloud.stream.messaging.Source
-
sinks - applications with a single input channel named
input
, typically having a single binding of the typeorg.springframework.cloud.stream.messaging.Sink
-
processors - applications with a single input channel named
input
and a single output channel namedoutput
, typically having a single binding of the typeorg.springframework.cloud.stream.messaging.Processor
.
They can be aggregated together by creating a sequence of interconnected applications, in which the output channel of an element in the sequence is connected to the input channel of the next element, if it exists. A sequence can start with either a source or a processor, it can contain an arbitrary number of processors and must end with either a processor or a sink.
Depending on the nature of the starting and ending element, the sequence may have one or more bindable channels, as follows:
-
if the sequence starts with a source and ends with a sink, all communication between the applications is direct and no channels will be bound
-
if the sequence starts with a processor, then its input channel will become the
input
channel of the aggregate and will be bound accordingly -
if the sequence ends with a processor, then its output channel will become the
output
channel of the aggregate and will be bound accordingly
Aggregation is performed using the AggregateApplicationBuilder
utility class, as in the following example.
Let’s consider a project in which we have source, processor and a sink, which may be defined in the project, or may be contained in one of the project’s dependencies.
@SpringBootApplication
@EnableBinding(Sink.class)
public class SinkApplication {
private static Logger logger = LoggerFactory.getLogger(SinkModuleDefinition.class);
@ServiceActivator(inputChannel=Sink.INPUT)
public void loggerSink(Object payload) {
logger.info("Received: " + payload);
}
}
@SpringBootApplication
@EnableBinding(Processor.class)
public class ProcessorApplication {
@Transformer
public String loggerSink(String payload) {
return payload.toUpperCase();
}
}
@SpringBootApplication
@EnableBinding(Source.class)
public class SourceApplication {
@Bean
@InboundChannelAdapter(value = Source.OUTPUT)
public String timerMessageSource() {
return new SimpleDateFormat().format(new Date());
}
}
Each configuration can be used for running a separate component, but in this case they can be aggregated together as follows:
@SpringBootApplication
public class SampleAggregateApplication {
public static void main(String[] args) {
new AggregateApplicationBuilder()
.from(SourceApplication.class).args("--fixedDelay=5000")
.via(ProcessorApplication.class)
.to(SinkApplication.class).args("--debug=true").run(args);
}
}
The starting component of the sequence is provided as argument to the from()
method.
The ending component of the sequence is provided as argument to the to()
method.
Intermediate processors are provided as argument to the via()
method.
Multiple processors of the same type can be chained together (e.g. for pipelining transformations with different configurations).
For each component, the builder can provide runtime arguments for Spring Boot configuration.
Configuring aggregate application
Spring Cloud Stream supports passing properties for the individual applications inside the aggregate application using 'namespace' as prefix.
The namespace can be set for applications as follows:
@SpringBootApplication
public class SampleAggregateApplication {
public static void main(String[] args) {
new AggregateApplicationBuilder()
.from(SourceApplication.class).namespace("source").args("--fixedDelay=5000")
.via(ProcessorApplication.class).namespace("processor1")
.to(SinkApplication.class).namespace("sink").args("--debug=true").run(args);
}
}
Once the 'namespace' is set for the individual applications, the application properties with the namespace
as prefix can be passed to the aggregate application using any supported property source (commandline, environment properties etc.,)
For instance, to override the default fixedDelay
and debug
properties of 'source' and 'sink' applications:
java -jar target/MyAggregateApplication-0.0.1-SNAPSHOT.jar --source.fixedDelay=10000 --sink.debug=false
Binders
Spring Cloud Stream provides a Binder abstraction for use in connecting to physical destinations at the external middleware. This section provides information about the main concepts behind the Binder SPI, its main components, and implementation-specific details.
Producers and Consumers
A producer is any component that sends messages to a channel.
The channel can be bound to an external message broker via a Binder implementation for that broker.
When invoking the bindProducer()
method, the first parameter is the name of the destination within the broker, the second parameter is the local channel instance to which the producer will send messages, and the third parameter contains properties (such as a partition key expression) to be used within the adapter that is created for that channel.
A consumer is any component that receives messages from a channel.
As with a producer, the consumer’s channel can be bound to an external message broker.
When invoking the bindConsumer()
method, the first parameter is the destination name, and a second parameter provides the name of a logical group of consumers.
Each group that is represented by consumer bindings for a given destination receives a copy of each message that a producer sends to that destination (i.e., publish-subscribe semantics).
If there are multiple consumer instances bound using the same group name, then messages will be load-balanced across those consumer instances so that each message sent by a producer is consumed by only a single consumer instance within each group (i.e., queueing semantics).
Binder SPI
The Binder SPI consists of a number of interfaces, out-of-the box utility classes and discovery strategies that provide a pluggable mechanism for connecting to external middleware.
The key point of the SPI is the Binder
interface which is a strategy for connecting inputs and outputs to external middleware.
public interface Binder<T, C extends ConsumerProperties, P extends ProducerProperties> {
Binding<T> bindConsumer(String name, String group, T inboundBindTarget, C consumerProperties);
Binding<T> bindProducer(String name, T outboundBindTarget, P producerProperties);
}
The interface is parameterized, offering a number of extension points:
-
input and output bind targets - as of version 1.0, only
MessageChannel
is supported, but this is intended to be used as an extension point in the future; -
extended consumer and producer properties - allowing specific Binder implementations to add supplemental properties which can be supported in a type-safe manner.
A typical binder implementation consists of the following
-
a class that implements the
Binder
interface; -
a Spring
@Configuration
class that creates a bean of the type above along with the middleware connection infrastructure; -
a
META-INF/spring.binders
file found on the classpath containing one or more binder definitions, e.g.
kafka:\
org.springframework.cloud.stream.binder.kafka.config.KafkaBinderConfiguration
Binder Detection
Spring Cloud Stream relies on implementations of the Binder SPI to perform the task of connecting channels to message brokers. Each Binder implementation typically connects to one type of messaging system.
Classpath Detection
By default, Spring Cloud Stream relies on Spring Boot’s auto-configuration to configure the binding process. If a single Binder implementation is found on the classpath, Spring Cloud Stream will use it automatically. For example, a Spring Cloud Stream project that aims to bind only to RabbitMQ can simply add the following dependency:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
For the specific maven coordinates of other binder dependencies, please refer to the documentation of that binder implementation.
Multiple Binders on the Classpath
When multiple binders are present on the classpath, the application must indicate which binder is to be used for each channel binding.
Each binder configuration contains a META-INF/spring.binders
, which is a simple properties file:
rabbit:\
org.springframework.cloud.stream.binder.rabbit.config.RabbitServiceAutoConfiguration
Similar files exist for the other provided binder implementations (e.g., Kafka), and custom binder implementations are expected to provide them, as well.
The key represents an identifying name for the binder implementation, whereas the value is a comma-separated list of configuration classes that each contain one and only one bean definition of type org.springframework.cloud.stream.binder.Binder
.
Binder selection can either be performed globally, using the spring.cloud.stream.defaultBinder
property (e.g., spring.cloud.stream.defaultBinder=rabbit
) or individually, by configuring the binder on each channel binding.
For instance, a processor application (that has channels with the names input
and output
for read/write respectively) which reads from Kafka and writes to RabbitMQ can specify the following configuration:
spring.cloud.stream.bindings.input.binder=kafka spring.cloud.stream.bindings.output.binder=rabbit
Connecting to Multiple Systems
By default, binders share the application’s Spring Boot auto-configuration, so that one instance of each binder found on the classpath will be created. If your application should connect to more than one broker of the same type, you can specify multiple binder configurations, each with different environment settings.
Note
|
Turning on explicit binder configuration will disable the default binder configuration process altogether.
If you do this, all binders in use must be included in the configuration.
Frameworks that intend to use Spring Cloud Stream transparently may create binder configurations that can be referenced by name, but will not affect the default binder configuration.
In order to do so, a binder configuration may have its |
For example, this is the typical configuration for a processor application which connects to two RabbitMQ broker instances:
spring:
cloud:
stream:
bindings:
input:
destination: foo
binder: rabbit1
output:
destination: bar
binder: rabbit2
binders:
rabbit1:
type: rabbit
environment:
spring:
rabbitmq:
host: <host1>
rabbit2:
type: rabbit
environment:
spring:
rabbitmq:
host: <host2>
Binder configuration properties
The following properties are available when creating custom binder configurations.
They must be prefixed with spring.cloud.stream.binders.<configurationName>
.
- type
-
The binder type. It typically references one of the binders found on the classpath, in particular a key in a
META-INF/spring.binders
file.By default, it has the same value as the configuration name.
- inheritEnvironment
-
Whether the configuration will inherit the environment of the application itself.
Default
true
. - environment
-
Root for a set of properties that can be used to customize the environment of the binder. When this is configured, the context in which the binder is being created is not a child of the application context. This allows for complete separation between the binder components and the application components.
Default
empty
. - defaultCandidate
-
Whether the binder configuration is a candidate for being considered a default binder, or can be used only when explicitly referenced. This allows adding binder configurations without interfering with the default processing.
Default
true
.
Configuration Options
Spring Cloud Stream supports general configuration options as well as configuration for bindings and binders. Some binders allow additional binding properties to support middleware-specific features.
Configuration options can be provided to Spring Cloud Stream applications via any mechanism supported by Spring Boot. This includes application arguments, environment variables, and YAML or .properties files.
Spring Cloud Stream Properties
- spring.cloud.stream.instanceCount
-
The number of deployed instances of an application. Must be set for partitioning and if using Kafka.
Default:
1
. - spring.cloud.stream.instanceIndex
-
The instance index of the application: a number from
0
toinstanceCount
-1. Used for partitioning and with Kafka. Automatically set in Cloud Foundry to match the application’s instance index. - spring.cloud.stream.dynamicDestinations
-
A list of destinations that can be bound dynamically (for example, in a dynamic routing scenario). If set, only listed destinations can be bound.
Default: empty (allowing any destination to be bound).
- spring.cloud.stream.defaultBinder
-
The default binder to use, if multiple binders are configured. See Multiple Binders on the Classpath.
Default: empty.
- spring.cloud.stream.overrideCloudConnectors
-
This property is only applicable when the
cloud
profile is active and Spring Cloud Connectors are provided with the application. If the property is false (the default), the binder will detect a suitable bound service (e.g. a RabbitMQ service bound in Cloud Foundry for the RabbitMQ binder) and will use it for creating connections (usually via Spring Cloud Connectors). When set to true, this property instructs binders to completely ignore the bound services and rely on Spring Boot properties (e.g. relying on thespring.rabbitmq.*
properties provided in the environment for the RabbitMQ binder). The typical usage of this property is to be nested in a customized environment when connecting to multiple systems.Default: false.
Binding Properties
Binding properties are supplied using the format spring.cloud.stream.bindings.<channelName>.<property>=<value>
.
The <channelName>
represents the name of the channel being configured (e.g., output
for a Source
).
To avoid repetition, Spring Cloud Stream supports setting values for all channels, in the format spring.cloud.stream.default.<property>=<value>
.
In what follows, we indicate where we have omitted the spring.cloud.stream.bindings.<channelName>.
prefix and focus just on the property name, with the understanding that the prefix will be included at runtime.
Properties for Use of Spring Cloud Stream
The following binding properties are available for both input and output bindings and must be prefixed with spring.cloud.stream.bindings.<channelName>.
, e.g. spring.cloud.stream.bindings.input.destination=ticktock
.
Default values can be set by using the prefix spring.cloud.stream.default
, e.g. spring.cloud.stream.default.contentType=application/json
.
- destination
-
The target destination of a channel on the bound middleware (e.g., the RabbitMQ exchange or Kafka topic). If the channel is bound as a consumer, it could be bound to multiple destinations and the destination names can be specified as comma separated String values. If not set, the channel name is used instead. The default value of this property cannot be overridden.
- group
-
The consumer group of the channel. Applies only to inbound bindings. See Consumer Groups.
Default: null (indicating an anonymous consumer).
- contentType
-
The content type of the channel.
Default: null (so that no type coercion is performed).
- binder
-
The binder used by this binding. See Multiple Binders on the Classpath for details.
Default: null (the default binder will be used, if one exists).
Consumer properties
The following binding properties are available for input bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.consumer.
, e.g. spring.cloud.stream.bindings.input.consumer.concurrency=3
.
Default values can be set by using the prefix spring.cloud.stream.default.consumer
, e.g. spring.cloud.stream.default.consumer.headerMode=raw
.
- concurrency
-
The concurrency of the inbound consumer.
Default:
1
. - partitioned
-
Whether the consumer receives data from a partitioned producer.
Default:
false
. - headerMode
-
When set to
raw
, disables header parsing on input. Effective only for messaging middleware that does not support message headers natively and requires header embedding. Useful when inbound data is coming from outside Spring Cloud Stream applications.Default:
embeddedHeaders
. - maxAttempts
-
The number of attempts of re-processing an inbound message.
Default:
3
. - backOffInitialInterval
-
The backoff initial interval on retry.
Default:
1000
. - backOffMaxInterval
-
The maximum backoff interval.
Default:
10000
. - backOffMultiplier
-
The backoff multiplier.
Default:
2.0
. - instanceIndex
-
When set to a value greater than equal to zero, allows customizing the instance index of this consumer (if different from
spring.cloud.stream.instanceIndex
). When set to a negative value, it will default tospring.cloud.stream.instanceIndex
.Default:
-1
. - instanceCount
-
When set to a value greater than equal to zero, allows customizing the instance count of this consumer (if different from
spring.cloud.stream.instanceCount
). When set to a negative value, it will default tospring.cloud.stream.instanceCount
.Default:
-1
.
Producer Properties
The following binding properties are available for output bindings only and must be prefixed with spring.cloud.stream.bindings.<channelName>.producer.
, e.g. spring.cloud.stream.bindings.input.producer.partitionKeyExpression=payload.id
.
Default values can be set by using the prefix spring.cloud.stream.default.producer
, e.g. spring.cloud.stream.default.producer.partitionKeyExpression=payload.id
.
- partitionKeyExpression
-
A SpEL expression that determines how to partition outbound data. If set, or if
partitionKeyExtractorClass
is set, outbound data on this channel will be partitioned, andpartitionCount
must be set to a value greater than 1 to be effective. The two options are mutually exclusive. See Partitioning Support.Default: null.
- partitionKeyExtractorClass
-
A
PartitionKeyExtractorStrategy
implementation. If set, or ifpartitionKeyExpression
is set, outbound data on this channel will be partitioned, andpartitionCount
must be set to a value greater than 1 to be effective. The two options are mutually exclusive. See Partitioning Support.Default: null.
- partitionSelectorClass
-
A
PartitionSelectorStrategy
implementation. Mutually exclusive withpartitionSelectorExpression
. If neither is set, the partition will be selected as thehashCode(key) % partitionCount
, wherekey
is computed via eitherpartitionKeyExpression
orpartitionKeyExtractorClass
.Default: null.
- partitionSelectorExpression
-
A SpEL expression for customizing partition selection. Mutually exclusive with
partitionSelectorClass
. If neither is set, the partition will be selected as thehashCode(key) % partitionCount
, wherekey
is computed via eitherpartitionKeyExpression
orpartitionKeyExtractorClass
.Default: null.
- partitionCount
-
The number of target partitions for the data, if partitioning is enabled. Must be set to a value greater than 1 if the producer is partitioned. On Kafka, interpreted as a hint; the larger of this and the partition count of the target topic is used instead.
Default:
1
. - requiredGroups
-
A comma-separated list of groups to which the producer must ensure message delivery even if they start after it has been created (e.g., by pre-creating durable queues in RabbitMQ).
- headerMode
-
When set to
raw
, disables header embedding on output. Effective only for messaging middleware that does not support message headers natively and requires header embedding. Useful when producing data for non-Spring Cloud Stream applications.Default:
embeddedHeaders
. - useNativeEncoding
-
When set to
true
, the outbound message is serialized directly by client library, which must be configured correspondingly (e.g. setting an appropriate Kafka producer value serializer). When this configuration is being used, the outbound message marshalling is not based on thecontentType
of the binding. When native encoding is used, it is the responsibility of the consumer to use appropriate decoder (ex: Kafka consumer value de-serializer) to deserialize the inbound message. Also, when native encoding/decoding is used theheaderMode
property is ignored and headers will not be embedded into the message.Default:
false
.
Content Type and Transformation
To allow you to propagate information about the content type of produced messages, Spring Cloud Stream attaches, by default, a contentType
header to outbound messages.
For middleware that does not directly support headers, Spring Cloud Stream provides its own mechanism of automatically wrapping outbound messages in an envelope of its own.
For middleware that does support headers, Spring Cloud Stream applications may receive messages with a given content type from non-Spring Cloud Stream applications.
Spring Cloud Stream can handle messages based on this information in two ways:
-
Through its
contentType
settings on inbound and outbound channels -
Through its argument mapping performed for methods annotated with
@StreamListener
Spring Cloud Stream allows you to declaratively configure type conversion for inputs and outputs using the spring.cloud.stream.bindings.<channelName>.content-type
property of a binding.
Note that general type conversion may also be accomplished easily by using a transformer inside your application.
Currently, Spring Cloud Stream natively supports the following type conversions commonly used in streams:
-
JSON to/from POJO
-
JSON to/from org.springframework.tuple.Tuple
-
Object to/from byte[] : Either the raw bytes serialized for remote transport, bytes emitted by an application, or converted to bytes using Java serialization(requires the object to be Serializable)
-
String to/from byte[]
-
Object to plain text (invokes the object’s toString() method)
Where JSON represents either a byte array or String payload containing JSON. Currently, Objects may be converted from a JSON byte array or String. Converting to JSON always produces a String.
MIME types
content-type
values are parsed as media types, e.g., application/json
or text/plain;charset=UTF-8
.
MIME types are especially useful for indicating how to convert to String or byte[] content.
Spring Cloud Stream also uses MIME type format to represent Java types, using the general type application/x-java-object
with a type
parameter.
For example, application/x-java-object;type=java.util.Map
or application/x-java-object;type=com.bar.Foo
can be set as the content-type
property of an input binding.
In addition, Spring Cloud Stream provides custom MIME types, notably, application/x-spring-tuple
to specify a Tuple.
MIME types and Java types
The type conversions Spring Cloud Stream provides out of the box are summarized in the following table:
Source Payload | Target Payload | content-type header | content-type | Comments |
---|---|---|---|---|
POJO |
JSON String |
ignored |
application/json |
|
Tuple |
JSON String |
ignored |
application/json |
JSON is tailored for Tuple |
POJO |
String (toString()) |
ignored |
text/plain, java.lang.String |
|
POJO |
byte[] (java.io serialized) |
ignored |
application/x-java-serialized-object |
|
JSON byte[] or String |
POJO |
application/json (or none) |
application/x-java-object |
|
byte[] or String |
Serializable |
application/x-java-serialized-object |
application/x-java-object |
|
JSON byte[] or String |
Tuple |
application/json (or none) |
application/x-spring-tuple |
|
byte[] |
String |
any |
text/plain, java.lang.String |
will apply any Charset specified in the content-type header |
String |
byte[] |
any |
application/octet-stream |
will apply any Charset specified in the content-type header |
Conversion applies to payloads that require type conversion. For example, if a module produces an XML string with outputType=application/json, the payload will not be converted from XML to JSON. This is because the payload at the module’s output channel is already a String so no conversion will be applied at runtime.
While conversion is supported for both input and output channels, it is especially recommended to be used for the conversion of outbound messages.
For the conversion of inbound messages, especially when the target is a POJO, the @StreamListener
support will perform the conversion automatically.
Customizing message conversion
Besides the conversions that it supports out of the box, Spring Cloud Stream also supports registering your own message conversion implementations.
This allows you to send and receive data in a variety of custom formats, including binary, and associate them with specific contentTypes
.
Spring Cloud Stream registers all the beans of type org.springframework.messaging.converter.MessageConverter
as custom message converters along with the out of the box message converters.
If your message converter needs to work with a specific content-type
and target class (for both input and output), then the message converter needs to extend org.springframework.messaging.converter.AbstractMessageConverter
.
For conversion when using @StreamListener
, a message converter that implements org.springframework.messaging.converter.MessageConverter
would suffice.
Here is an example of creating a message converter bean (with the content-type application/bar
) inside a Spring Cloud Stream application:
@EnableBinding(Sink.class)
@SpringBootApplication
public static class SinkApplication {
...
@Bean
public MessageConverter customMessageConverter() {
return new MyCustomMessageConverter();
}
public class MyCustomMessageConverter extends AbstractMessageConverter {
public MyCustomMessageConverter() {
super(new MimeType("application", "bar"));
}
@Override
protected boolean supports(Class<?> clazz) {
return (Bar.class == clazz);
}
@Override
protected Object convertFromInternal(Message<?> message, Class<?> targetClass, Object conversionHint) {
Object payload = message.getPayload();
return (payload instanceof Bar ? payload : new Bar((byte[]) payload));
}
}
Schema-based message converters
Spring Cloud Stream provides support for schema-based message converters through its spring-cloud-stream-schema
module.
Currently, the only serialization format supported out of the box is Apache Avro, with more formats to be added in future versions.
Apache Avro Message Converters
The spring-cloud-stream-schema
module contains two types of message converters that can be used for Apache Avro serialization:
-
converters using the class information of the serialized/deserialized objects, or a schema with a location known at startup;
-
converters using a schema registry - they locate the schemas at runtime, as well as dynamically registering new schemas as domain objects evolve.
Converters with schema support
The AvroSchemaMessageConverter
supports serializing and deserializing messages either using a predefined schema or by using the schema information available in the class (either reflectively, or contained in the SpecificRecord
).
If the target type of the conversion is a GenericRecord
, then a schema must be set.
For using it, you can simply add it to the application context, optionally specifying one ore more MimeTypes
to associate it with.
The default MimeType
is application/avro
.
Here is an example of configuring it in a sink application registering the Apache Avro MessageConverter
, without a predefined schema:
@EnableBinding(Sink.class)
@SpringBootApplication
public static class SinkApplication {
...
@Bean
public MessageConverter userMessageConverter() {
return new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
}
}
Conversely, here is an application that registers a converter with a predefined schema, to be found on the classpath:
@EnableBinding(Sink.class)
@SpringBootApplication
public static class SinkApplication {
...
@Bean
public MessageConverter userMessageConverter() {
AvroSchemaMessageConverter converter = new AvroSchemaMessageConverter(MimeType.valueOf("avro/bytes"));
converter.setSchemaLocation(new ClassPathResource("schemas/User.avro"));
return converter;
}
}
In order to understand the schema registry client converter, we will describe the schema registry support first.
Schema Registry Support
Most serialization models, especially the ones that aim for portability across different platforms and languages, rely on a schema that describes how the data is serialized in the binary payload. In order to serialize the data and then to interpret it, both the sending and receiving sides must have access to a schema that describes the binary format. In certain cases, the schema can be inferred from the payload type on serialization, or from the target type on deserialization, but in a lot of cases applications benefit from having access to an explicit schema that describes the binary data format. A schema registry allows you to store schema information in a textual format (typically JSON) and makes that information accessible to various applications that need it to receive and send data in binary format. A schema is referenceable as a tuple consisting of:
-
a subject that is the logical name of the schema;
-
the schema version;
-
the schema format which describes the binary format of the data.
Schema Registry Server
Spring Cloud Stream provides a schema registry server implementation.
In order to use it, you can simply add the spring-cloud-stream-schema-server
artifact to your project and use the @EnableSchemaRegistryServer
annotation, adding the schema registry server REST controller to your application.
This annotation is intended to be used with Spring Boot web applications, and the listening port of the server is controlled by the server.port
setting.
The spring.cloud.stream.schema.server.path
setting can be used to control the root path of the schema server (especially when it is embedded in other applications).
The spring.cloud.stream.schema.server.allowSchemaDeletion
boolean setting enables the deletion of schema. By default this is disabled.
The schema registry server uses a relational database to store the schemas. By default, it uses an embedded database. You can customize the schema storage using the Spring Boot SQL database and JDBC configuration options.
A Spring Boot application enabling the schema registry looks as follows:
@SpringBootApplication
@EnableSchemaRegistryServer
public class SchemaRegistryServerApplication {
public static void main(String[] args) {
SpringApplication.run(SchemaRegistryServerApplication.class, args);
}
}
Schema Registry Server API
The Schema Registry Server API consists of the following operations:
POST /
Register a new schema.
Accepts JSON payload with the following fields:
-
subject
the schema subject; -
format
the schema format; -
definition
the schema definition.
Response is a schema object in JSON format, with the following fields:
-
id
the schema id; -
subject
the schema subject; -
format
the schema format; -
version
the schema version; -
definition
the schema definition.
GET /{subject}/{format}/{version}
Retrieve an existing schema by its subject, format and version.
Response is a schema object in JSON format, with the following fields:
-
id
the schema id; -
subject
the schema subject; -
format
the schema format; -
version
the schema version; -
definition
the schema definition.
GET /schemas/{id}
Retrieve an existing schema by its id.
Response is a schema object in JSON format, with the following fields:
-
id
the schema id; -
subject
the schema subject; -
format
the schema format; -
version
the schema version; -
definition
the schema definition.
DELETE /{subject}/{format}/{version}
Delete an existing schema by its subject, format and version.
DELETE /schemas/{id}
Delete an existing schema by its id.
DELETE /{subject}
Delete existing schemas by their subject.
Note
|
This note applies to users of Spring Cloud Stream 1.1.0.RELEASE only.
Spring Cloud Stream 1.1.0.RELEASE used the table name |
Schema Registry Client
The client-side abstraction for interacting with schema registry servers is the SchemaRegistryClient
interface, with the following structure:
public interface SchemaRegistryClient {
SchemaRegistrationResponse register(String subject, String format, String schema);
String fetch(SchemaReference schemaReference);
String fetch(Integer id);
}
Spring Cloud Stream provides out of the box implementations for interacting with its own schema server, as well as for interacting with the Confluent Schema Registry.
A client for the Spring Cloud Stream schema registry can be configured using the @EnableSchemaRegistryClient
as follows:
@EnableBinding(Sink.class)
@SpringBootApplication
@EnableSchemaRegistryClient
public static class AvroSinkApplication {
...
}
Avro Schema Registry Client Message Converters
For Spring Boot applications that have a SchemaRegistryClient
bean registered with the application context, Spring Cloud Stream will auto-configure an Apache Avro message converter that uses the schema registry client for schema management.
This eases schema evolution, as applications that receive messages can get easy access to a writer schema that can be reconciled with their own reader schema.
For outbound messages, the MessageConverter
will be activated if the content type of the channel is set to application/*+avro
, e.g.:
spring.cloud.stream.bindings.output.contentType=application/*+avro
During the outbound conversion, the message converter will try to infer the schemas of the outbound messages based on their type and register them to a subject based on the payload type using the SchemaRegistryClient
.
If an identical schema is already found, then a reference to it will be retrieved.
If not, the schema will be registered and a new version number will be provided.
The message will be sent with a contentType
header using the scheme application/[prefix].[subject].v[version]+avro
, where prefix
is configurable and subject
is deduced from the payload type.
For example, a message of the type User
may be sent as a binary payload with a content type of application/vnd.user.v2+avro
, where user
is the subject and 2
is the version number.
When receiving messages, the converter will infer the schema reference from the header of the incoming message and will try to retrieve it. The schema will be used as the writer schema in the deserialization process.
@StreamListener
and Message Conversion
The @StreamListener
annotation provides a convenient way for converting incoming messages without the need to specify the content type of an input channel.
During the dispatching process to methods annotated with @StreamListener
, a conversion will be applied automatically if the argument requires it.
For example, let’s consider a message with the String content {"greeting":"Hello, world"}
and a content-type
header of application/json
is received on the input channel.
Let us consider the following application that receives it:
public class GreetingMessage {
String greeting;
public String getGreeting() {
return greeting;
}
public void setGreeting(String greeting) {
this.greeting = greeting;
}
}
@EnableBinding(Sink.class)
@EnableAutoConfiguration
public static class GreetingSink {
@StreamListener(Sink.INPUT)
public void receive(Greeting greeting) {
// handle Greeting
}
}
The argument of the method will be populated automatically with the POJO containing the unmarshalled form of the JSON String.
Inter-Application Communication
Connecting Multiple Application Instances
While Spring Cloud Stream makes it easy for individual Spring Boot applications to connect to messaging systems, the typical scenario for Spring Cloud Stream is the creation of multi-application pipelines, where microservice applications send data to each other. You can achieve this scenario by correlating the input and output destinations of adjacent applications.
Supposing that a design calls for the Time Source application to send data to the Log Sink application, you can use a common destination named ticktock
for bindings within both applications.
Time Source (that has the channel name output
) will set the following property:
spring.cloud.stream.bindings.output.destination=ticktock
Log Sink (that has the channel name input
) will set the following property:
spring.cloud.stream.bindings.input.destination=ticktock
Instance Index and Instance Count
When scaling up Spring Cloud Stream applications, each instance can receive information about how many other instances of the same application exist and what its own instance index is.
Spring Cloud Stream does this through the spring.cloud.stream.instanceCount
and spring.cloud.stream.instanceIndex
properties.
For example, if there are three instances of a HDFS sink application, all three instances will have spring.cloud.stream.instanceCount
set to 3
, and the individual applications will have spring.cloud.stream.instanceIndex
set to 0
, 1
, and 2
, respectively.
When Spring Cloud Stream applications are deployed via Spring Cloud Data Flow, these properties are configured automatically; when Spring Cloud Stream applications are launched independently, these properties must be set correctly.
By default, spring.cloud.stream.instanceCount
is 1
, and spring.cloud.stream.instanceIndex
is 0
.
In a scaled-up scenario, correct configuration of these two properties is important for addressing partitioning behavior (see below) in general, and the two properties are always required by certain binders (e.g., the Kafka binder) in order to ensure that data are split correctly across multiple consumer instances.
Partitioning
Configuring Output Bindings for Partitioning
An output binding is configured to send partitioned data by setting one and only one of its partitionKeyExpression
or partitionKeyExtractorClass
properties, as well as its partitionCount
property.
For example, the following is a valid and typical configuration:
spring.cloud.stream.bindings.output.producer.partitionKeyExpression=payload.id spring.cloud.stream.bindings.output.producer.partitionCount=5
Based on the above example configuration, data will be sent to the target partition using the following logic.
A partition key’s value is calculated for each message sent to a partitioned output channel based on the partitionKeyExpression
.
The partitionKeyExpression
is a SpEL expression which is evaluated against the outbound message for extracting the partitioning key.
Tip
|
If a SpEL expression is not sufficient for your needs, you can instead calculate the partition key value by setting the property |
Once the message key is calculated, the partition selection process will determine the target partition as a value between 0
and partitionCount - 1
.
The default calculation, applicable in most scenarios, is based on the formula key.hashCode() % partitionCount
.
This can be customized on the binding, either by setting a SpEL expression to be evaluated against the key (via the partitionSelectorExpression
property) or by setting a org.springframework.cloud.stream.binder.PartitionSelectorStrategy
implementation (via the partitionSelectorClass
property).
Additional properties can be configured for more advanced scenarios, as described in the following section.
Configuring Input Bindings for Partitioning
An input binding (with the channel name input
) is configured to receive partitioned data by setting its partitioned
property, as well as the instanceIndex
and instanceCount
properties on the application itself, as in the following example:
spring.cloud.stream.bindings.input.consumer.partitioned=true spring.cloud.stream.instanceIndex=3 spring.cloud.stream.instanceCount=5
The instanceCount
value represents the total number of application instances between which the data need to be partitioned, and the instanceIndex
must be a unique value across the multiple instances, between 0
and instanceCount - 1
.
The instance index helps each application instance to identify the unique partition (or, in the case of Kafka, the partition set) from which it receives data.
It is important to set both values correctly in order to ensure that all of the data is consumed and that the application instances receive mutually exclusive datasets.
While a scenario which using multiple instances for partitioned data processing may be complex to set up in a standalone case, Spring Cloud Dataflow can simplify the process significantly by populating both the input and output values correctly as well as relying on the runtime infrastructure to provide information about the instance index and instance count.
Testing
Spring Cloud Stream provides support for testing your microservice applications without connecting to a messaging system.
You can do that by using the TestSupportBinder
.
This is useful especially for unit testing your microservices.
The TestSupportBinder
allows users to interact with the bound channels and inspect what messages are sent and received by the application
For outbound message channels, the TestSupportBinder
registers a single subscriber and retains the messages emitted by the application in a MessageCollector
.
They can be retrieved during tests and have assertions made against them.
The user can also send messages to inbound message channels, so that the consumer application can consume the messages. The following example shows how to test both input and output channels on a processor.
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = ExampleTest.MyProcessor.class)
@IntegrationTest({"server.port=-1"})
@DirtiesContext
public class ExampleTest {
@Autowired
private Processor processor;
@Autowired
private BinderFactory<MessageChannel> binderFactory;
@Autowired
private MessageCollector messageCollector;
@Test
@SuppressWarnings("unchecked")
public void testWiring() {
Message<String> message = new GenericMessage<>("hello");
processor.input().send(message);
Message<String> received = (Message<String>) messageCollector.forChannel(processor.output()).poll();
assertThat(received.getPayload(), equalTo("hello world"));
}
@SpringBootApplication
@EnableBinding(Processor.class)
public static class MyProcessor {
@Autowired
private Processor channels;
@Transformer(inputChannel = Processor.INPUT, outputChannel = Processor.OUTPUT)
public String transform(String in) {
return in + " world";
}
}
}
In the example above, we are creating an application that has an input and an output channel, bound through the Processor
interface.
The bound interface is injected into the test so we can have access to both channels.
We are sending a message on the input channel and we are using the MessageCollector
provided by Spring Cloud Stream’s test support to capture the message has been sent to the output channel as a result.
Once we have received the message, we can validate that the component functions correctly.
Health Indicator
Spring Cloud Stream provides a health indicator for binders.
It is registered under the name of binders
and can be enabled or disabled by setting the management.health.binders.enabled
property.
Samples
For Spring Cloud Stream samples, please refer to the spring-cloud-stream-samples repository on GitHub.
Getting Started
To get started with creating Spring Cloud Stream applications, visit the Spring Initializr and create a new Maven project named "GreetingSource".
Select Spring Boot {supported-spring-boot-version} in the dropdown.
In the Search for dependencies text box type Stream Rabbit
or Stream Kafka
depending on what binder you want to use.
Next, create a new class, GreetingSource
, in the same package as the GreetingSourceApplication
class.
Give it the following code:
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.messaging.Source;
import org.springframework.integration.annotation.InboundChannelAdapter;
@EnableBinding(Source.class)
public class GreetingSource {
@InboundChannelAdapter(Source.OUTPUT)
public String greet() {
return "hello world " + System.currentTimeMillis();
}
}
The @EnableBinding
annotation is what triggers the creation of Spring Integration infrastructure components.
Specifically, it will create a Kafka connection factory, a Kafka outbound channel adapter, and the message channel defined inside the Source interface:
public interface Source {
String OUTPUT = "output";
@Output(Source.OUTPUT)
MessageChannel output();
}
The auto-configuration also creates a default poller, so that the greet()
method will be invoked once per second.
The standard Spring Integration @InboundChannelAdapter
annotation sends a message to the source’s output channel, using the return value as the payload of the message.
To test-drive this setup, run a Kafka message broker. An easy way to do this is to use a Docker image:
# On OS X
$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=`docker-machine ip \`docker-machine active\`` --env ADVERTISED_PORT=9092 spotify/kafka
# On Linux
$ docker run -p 2181:2181 -p 9092:9092 --env ADVERTISED_HOST=localhost --env ADVERTISED_PORT=9092 spotify/kafka
Build the application:
./mvnw clean package
The consumer application is coded in a similar manner.
Go back to Initializr and create another project, named LoggingSink.
Then create a new class, LoggingSink
, in the same package as the class LoggingSinkApplication
and with the following code:
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.StreamListener;
import org.springframework.cloud.stream.messaging.Sink;
@EnableBinding(Sink.class)
public class LoggingSink {
@StreamListener(Sink.INPUT)
public void log(String message) {
System.out.println(message);
}
}
Build the application:
./mvnw clean package
To connect the GreetingSource application to the LoggingSink application, each application must share the same destination name. Starting up both applications as shown below, you will see the consumer application printing "hello world" and a timestamp to the console:
cd GreetingSource
java -jar target/GreetingSource-0.0.1-SNAPSHOT.jar --spring.cloud.stream.bindings.output.destination=mydest
cd LoggingSink
java -jar target/LoggingSink-0.0.1-SNAPSHOT.jar --server.port=8090 --spring.cloud.stream.bindings.input.destination=mydest
(The different server port prevents collisions of the HTTP port used to service the Spring Boot Actuator endpoints in the two applications.)
The output of the LoggingSink application will look something like the following:
[ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8090 (http)
[ main] com.example.LoggingSinkApplication : Started LoggingSinkApplication in 6.828 seconds (JVM running for 7.371)
hello world 1458595076731
hello world 1458595077732
hello world 1458595078733
hello world 1458595079734
hello world 1458595080735
Binder Implementations
Apache Kafka Binder
Usage
For using the Apache Kafka binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-kafka</artifactId>
</dependency>
Alternatively, you can also use the Spring Cloud Stream Kafka Starter.
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-stream-kafka</artifactId>
</dependency>
Apache Kafka Binder Overview
A simplified diagram of how the Apache Kafka binder operates can be seen below.
The Apache Kafka Binder implementation maps each destination to an Apache Kafka topic. The consumer group maps directly to the same Apache Kafka concept. Partitioning also maps directly to Apache Kafka partitions as well.
Configuration Options
This section contains the configuration options used by the Apache Kafka binder.
For common configuration options and properties pertaining to binder, refer to the core docs.
Kafka Binder Properties
- spring.cloud.stream.kafka.binder.brokers
-
A list of brokers to which the Kafka binder will connect.
Default:
localhost
. - spring.cloud.stream.kafka.binder.defaultBrokerPort
-
brokers
allows hosts specified with or without port information (e.g.,host1,host2:port2
). This sets the default port when no port is configured in the broker list.Default:
9092
. - spring.cloud.stream.kafka.binder.zkNodes
-
A list of ZooKeeper nodes to which the Kafka binder can connect.
Default:
localhost
. - spring.cloud.stream.kafka.binder.defaultZkPort
-
zkNodes
allows hosts specified with or without port information (e.g.,host1,host2:port2
). This sets the default port when no port is configured in the node list.Default:
2181
. - spring.cloud.stream.kafka.binder.configuration
-
Key/Value map of client properties (both producers and consumer) passed to all clients created by the binder. Due to the fact that these properties will be used by both producers and consumers, usage should be restricted to common properties, especially security settings.
Default: Empty map.
- spring.cloud.stream.kafka.binder.headers
-
The list of custom headers that will be transported by the binder.
Default: empty.
- spring.cloud.stream.kafka.binder.offsetUpdateTimeWindow
-
The frequency, in milliseconds, with which offsets are saved. Ignored if
0
.Default:
10000
. - spring.cloud.stream.kafka.binder.offsetUpdateCount
-
The frequency, in number of updates, which which consumed offsets are persisted. Ignored if
0
. Mutually exclusive withoffsetUpdateTimeWindow
.Default:
0
. - spring.cloud.stream.kafka.binder.requiredAcks
-
The number of required acks on the broker.
Default:
1
. - spring.cloud.stream.kafka.binder.minPartitionCount
-
Effective only if
autoCreateTopics
orautoAddPartitions
is set. The global minimum number of partitions that the binder will configure on topics on which it produces/consumes data. It can be superseded by thepartitionCount
setting of the producer or by the value ofinstanceCount
*concurrency
settings of the producer (if either is larger).Default:
1
. - spring.cloud.stream.kafka.binder.replicationFactor
-
The replication factor of auto-created topics if
autoCreateTopics
is active.Default:
1
. - spring.cloud.stream.kafka.binder.autoCreateTopics
-
If set to
true
, the binder will create new topics automatically. If set tofalse
, the binder will rely on the topics being already configured. In the latter case, if the topics do not exist, the binder will fail to start. Of note, this setting is independent of theauto.topic.create.enable
setting of the broker and it does not influence it: if the server is set to auto-create topics, they may be created as part of the metadata retrieval request, with default broker settings.Default:
true
. - spring.cloud.stream.kafka.binder.autoAddPartitions
-
If set to
true
, the binder will create add new partitions if required. If set tofalse
, the binder will rely on the partition size of the topic being already configured. If the partition count of the target topic is smaller than the expected value, the binder will fail to start.Default:
false
. - spring.cloud.stream.kafka.binder.socketBufferSize
-
Size (in bytes) of the socket buffer to be used by the Kafka consumers.
Default:
2097152
.
Kafka Consumer Properties
The following properties are available for Kafka consumers only and
must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.consumer.
.
- autoRebalanceEnabled
-
When
true
, topic partitions will be automatically rebalanced between the members of a consumer group. Whenfalse
, each consumer will be assigned a fixed set of partitions based onspring.cloud.stream.instanceCount
andspring.cloud.stream.instanceIndex
. This requires bothspring.cloud.stream.instanceCount
andspring.cloud.stream.instanceIndex
properties to be set appropriately on each launched instance. The propertyspring.cloud.stream.instanceCount
must typically be greater than 1 in this case.Default:
true
. - autoCommitOffset
-
Whether to autocommit offsets when a message has been processed. If set to
false
, a header with the keykafka_acknowledgment
of the typeorg.springframework.kafka.support.Acknowledgment
header will be present in the inbound message. Applications may use this header for acknowledging messages. See the examples section for details. When this property is set tofalse
, Kafka binder will set the ack mode toorg.springframework.kafka.listener.AbstractMessageListenerContainer.AckMode.MANUAL
.Default:
true
. - autoCommitOnError
-
Effective only if
autoCommitOffset
is set totrue
. If set tofalse
it suppresses auto-commits for messages that result in errors, and will commit only for successful messages, allows a stream to automatically replay from the last successfully processed message, in case of persistent failures. If set totrue
, it will always auto-commit (if auto-commit is enabled). If not set (default), it effectively has the same value asenableDlq
, auto-committing erroneous messages if they are sent to a DLQ, and not committing them otherwise.Default: not set.
- recoveryInterval
-
The interval between connection recovery attempts, in milliseconds.
Default:
5000
. - resetOffsets
-
Whether to reset offsets on the consumer to the value provided by
startOffset
.Default:
false
. - startOffset
-
The starting offset for new groups, or when
resetOffsets
istrue
. Allowed values:earliest
,latest
.Default: null (equivalent to
earliest
). - enableDlq
-
When set to true, it will send enable DLQ behavior for the consumer. Messages that result in errors will be forwarded to a topic named
error.<destination>.<group>
. This provides an alternative option to the more common Kafka replay scenario for the case when the number of errors is relatively small and replaying the entire original topic may be too cumbersome.Default:
false
. - configuration
-
Map with a key/value pair containing generic Kafka consumer properties.
Default: Empty map.
Kafka Producer Properties
The following properties are available for Kafka producers only and
must be prefixed with spring.cloud.stream.kafka.bindings.<channelName>.producer.
.
- bufferSize
-
Upper limit, in bytes, of how much data the Kafka producer will attempt to batch before sending.
Default:
16384
. - sync
-
Whether the producer is synchronous.
Default:
false
. - batchTimeout
-
How long the producer will wait before sending in order to allow more messages to accumulate in the same batch. (Normally the producer does not wait at all, and simply sends all the messages that accumulated while the previous send was in progress.) A non-zero value may increase throughput at the expense of latency.
Default:
0
. - configuration
-
Map with a key/value pair containing generic Kafka producer properties.
Default: Empty map.
Note
|
The Kafka binder will use the |
Usage examples
In this section, we illustrate the use of the above properties for specific scenarios.
Example: Setting autoCommitOffset
false and relying on manual acking.
This example illustrates how one may manually acknowledge offsets in a consumer application.
This example requires that spring.cloud.stream.kafka.bindings.input.consumer.autoCommitOffset
is set to false.
Use the corresponding input channel name for your example.
@SpringBootApplication
@EnableBinding(Sink.class)
public class ManuallyAcknowdledgingConsumer {
public static void main(String[] args) {
SpringApplication.run(ManuallyAcknowdledgingConsumer.class, args);
}
@StreamListener(Sink.INPUT)
public void process(Message<?> message) {
Acknowledgment acknowledgment = message.getHeaders().get(KafkaHeaders.ACKNOWLEDGMENT, Acknowledgment.class);
if (acknowledgment != null) {
System.out.println("Acknowledgment provided");
acknowledgment.acknowledge();
}
}
}
Example: security configuration
Apache Kafka 0.9 supports secure connections between client and brokers.
To take advantage of this feature, follow the guidelines in the Apache Kafka Documentation as well as the Kafka 0.9 security guidelines from the Confluent documentation.
Use the spring.cloud.stream.kafka.binder.configuration
option to set security properties for all clients created by the binder.
For example, for setting security.protocol
to SASL_SSL
, set:
spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_SSL
All the other security properties can be set in a similar manner.
When using Kerberos, follow the instructions in the reference documentation for creating and referencing the JAAS configuration.
Spring Cloud Stream supports passing JAAS configuration information to the application using a JAAS configuration file and using Spring Boot properties.
Using JAAS configuration files
The JAAS, and (optionally) krb5 file locations can be set for Spring Cloud Stream applications by using system properties. Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using a JAAS configuration file:
java -Djava.security.auth.login.config=/path.to/kafka_client_jaas.conf -jar log.jar \
--spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
--spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
--spring.cloud.stream.bindings.input.destination=stream.ticktock \
--spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT
Using Spring Boot properties
As an alternative to having a JAAS configuration file, Spring Cloud Stream provides a mechanism for setting up the JAAS configuration for Spring Cloud Stream applications using Spring Boot properties.
The following properties can be used for configuring the login context of the Kafka client.
- spring.cloud.stream.kafka.binder.jaas.loginModule
-
The login module name. Not necessary to be set in normal cases.
Default:
com.sun.security.auth.module.Krb5LoginModule
. - spring.cloud.stream.kafka.binder.jaas.controlFlag
-
The control flag of the login module.
Default:
required
. - spring.cloud.stream.kafka.binder.jaas.options
-
Map with a key/value pair containing the login module options.
Default: Empty map.
Here is an example of launching a Spring Cloud Stream application with SASL and Kerberos using Spring Boot configuration properties:
java --spring.cloud.stream.kafka.binder.brokers=secure.server:9092 \
--spring.cloud.stream.kafka.binder.zkNodes=secure.zookeeper:2181 \
--spring.cloud.stream.bindings.input.destination=stream.ticktock \
--spring.cloud.stream.kafka.binder.autoCreateTopics=false \
--spring.cloud.stream.kafka.binder.configuration.security.protocol=SASL_PLAINTEXT \
--spring.cloud.stream.kafka.binder.jaas.options.useKeyTab=true \
--spring.cloud.stream.kafka.binder.jaas.options.storeKey=true \
--spring.cloud.stream.kafka.binder.jaas.options.keyTab=/etc/security/keytabs/kafka_client.keytab \
--spring.cloud.stream.kafka.binder.jaas.options.principal=kafka-client-1@EXAMPLE.COM
This represents the equivalent of the following JAAS file:
KafkaClient {
com.sun.security.auth.module.Krb5LoginModule required
useKeyTab=true
storeKey=true
keyTab="/etc/security/keytabs/kafka_client.keytab"
principal="[email protected]";
};
If the topics required already exist on the broker, or will be created by an administrator, autocreation can be turned off and only client JAAS properties need to be sent. As an alternative to setting spring.cloud.stream.kafka.binder.autoCreateTopics
you can simply remove the broker dependency from the application. See Excluding Kafka broker jar from the classpath of the binder based application for details.
Note
|
Do not mix JAAS configuration files and Spring Boot properties in the same application.
If the |
Note
|
Exercise caution when using the |
Using the binder with Apache Kafka 0.10
The binder also supports connecting to Kafka 0.10 brokers.
In order to support this, when you create the project that contains your application, include spring-cloud-starter-stream-kafka
as you normally would do for 0.9 based applications.
Then add these dependencies at the top of the <dependencies>
section in the pom.xml file to override the Apache Kafka, Spring Kafka, and Spring Integration Kafka with 0.10-compatible versions as in the following example:
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
<version>1.1.1.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.integration</groupId>
<artifactId>spring-integration-kafka</artifactId>
<version>2.1.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka_2.11</artifactId>
<version>0.10.0.0</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
</exclusions>
</dependency>
Note
|
The versions above are provided only for the sake of the example. For best results, we recommend using the most recent 0.10-compatible versions of the projects. |
Excluding Kafka broker jar from the classpath of the binder based application
The Apache Kafka Binder uses the administrative utilities which are part of the Apache Kafka server library to create and reconfigure topics. If the inclusion of the Apache Kafka server library and its dependencies is not necessary at runtime because the application will rely on the topics being configured administratively, the Kafka binder allows for Apache Kafka server dependency to be excluded from the application.
If you use Kafka 10 dependencies as advised above, all you have to do is not to include the kafka broker dependency.
If you use Kafka 0.9, then ensure that you exclude the kafka broker jar from the spring-cloud-starter-stream-kafka
dependency as following.
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-stream-kafka</artifactId>
<exclusions>
<exclusion>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka_2.11</artifactId>
</exclusion>
</exclusions>
</dependency>
If you exclude the Apache Kafka server dependency and the topic is not present on the server, then the Apache Kafka broker will create the topic if auto topic creation is enabled on the server. Please keep in mind that if you are relying on this, then the Kafka server will use the default number of partitions and replication factors. On the other hand, if auto topic creation is disabled on the server, then care must be taken before running the application to create the topic with the desired number of partitions.
If you want to have full control over how partitions are allocated, then leave the default settings as they are, i.e. do not exclude the kafka broker jar and ensure that spring.cloud.stream.kafka.binder.autoCreateTopics
is set to true
, which is the default.
RabbitMQ Binder
Usage
For using the RabbitMQ binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
Alternatively, you can also use the Spring Cloud Stream RabbitMQ Starter.
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-stream-rabbit</artifactId>
</dependency>
RabbitMQ Binder Overview
A simplified diagram of how the RabbitMQ binder operates can be seen below.
The RabbitMQ Binder implementation maps each destination to a TopicExchange
.
For each consumer group, a Queue
will be bound to that TopicExchange
.
Each consumer instance have a corresponding RabbitMQ Consumer
instance for its group’s Queue
.
For partitioned producers/consumers the queues are suffixed with the partition index and use the partition index as routing key.
Using the autoBindDlq
option, you can optionally configure the binder to create and configure dead-letter queues (DLQs) (and a dead-letter exchange DLX
).
The dead letter queue has the name of the destination, appended with .dlq
.
If retry is enabled (maxAttempts > 1
) failed messages will be delivered to the DLQ.
If retry is disabled (maxAttempts = 1
), you should set requeueRejected
to false
(default) so that a failed message will be routed to the DLQ, instead of being requeued.
In addition, republishToDlq
causes the binder to publish a failed message to the DLQ (instead of rejecting it); this enables additional information to be added to the message in headers, such as the stack trace in the x-exception-stacktrace
header.
This option does not need retry enabled; you can republish a failed message after just one attempt.
Important
|
Setting requeueRejected to true will cause the message to be requeued and redelivered continually, which is likely not what you want unless the failure issue is transient.
In general, it’s better to enable retry within the binder by setting maxAttempts to greater than one, or set republishToDlq to true .
|
See RabbitMQ Binder Properties for more information about these properties.
The framework does not provide any standard mechanism to consume dead-letter messages (or to re-route them back to the primary queue). Some options are described in Dead-Letter Queue Processing.
Configuration Options
This section contains settings specific to the RabbitMQ Binder and bound channels.
For general binding configuration options and properties, please refer to the Spring Cloud Stream core documentation.
RabbitMQ Binder Properties
By default, the RabbitMQ binder uses Spring Boot’s ConnectionFactory
, and it therefore supports all Spring Boot configuration options for RabbitMQ.
(For reference, consult the Spring Boot documentation.)
RabbitMQ configuration options use the spring.rabbitmq
prefix.
In addition to Spring Boot options, the RabbitMQ binder supports the following properties:
- spring.cloud.stream.rabbit.binder.adminAddresses
-
A comma-separated list of RabbitMQ management plugin URLs. Only used when
nodes
contains more than one entry. Each entry in this list must have a corresponding entry inspring.rabbitmq.addresses
.Default: empty.
- spring.cloud.stream.rabbit.binder.nodes
-
A comma-separated list of RabbitMQ node names. When more than one entry, used to locate the server address where a queue is located. Each entry in this list must have a corresponding entry in
spring.rabbitmq.addresses
.Default: empty.
- spring.cloud.stream.rabbit.binder.compressionLevel
-
Compression level for compressed bindings. See
java.util.zip.Deflater
.Default:
1
(BEST_LEVEL).
RabbitMQ Consumer Properties
The following properties are available for Rabbit consumers only and
must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.consumer.
.
- acknowledgeMode
-
The acknowledge mode.
Default:
AUTO
. - autoBindDlq
-
Whether to automatically declare the DLQ and bind it to the binder DLX.
Default:
false
. - durableSubscription
-
Whether subscription should be durable. Only effective if
group
is also set.Default:
true
. - maxConcurrency
-
Default:
1
. - prefetch
-
Prefetch count.
Default:
1
. - prefix
-
A prefix to be added to the name of the
destination
and queues.Default: "".
- recoveryInterval
-
The interval between connection recovery attempts, in milliseconds.
Default:
5000
. - requeueRejected
-
Whether delivery failures should be requeued when retry is disabled or republishToDlq is false.
Default:
false
. - requestHeaderPatterns
-
The request headers to be transported.
Default:
[STANDARD_REQUEST_HEADERS,'*']
. - replyHeaderPatterns
-
The reply headers to be transported.
Default:
[STANDARD_REPLY_HEADERS,'*']
. - republishToDlq
-
By default, messages which fail after retries are exhausted are rejected. If a dead-letter queue (DLQ) is configured, RabbitMQ will route the failed message (unchanged) to the DLQ. If set to
true
, the binder will republish failed messages to the DLQ with additional headers, including the exception message and stack trace from the cause of the final failure.Default: false
- transacted
-
Whether to use transacted channels.
Default:
false
. - txSize
-
The number of deliveries between acks.
Default:
1
.
Rabbit Producer Properties
The following properties are available for Rabbit producers only and
must be prefixed with spring.cloud.stream.rabbit.bindings.<channelName>.producer.
.
- autoBindDlq
-
Whether to automatically declare the DLQ and bind it to the binder DLX.
Default:
false
. - batchingEnabled
-
Whether to enable message batching by producers.
Default:
false
. - batchSize
-
The number of messages to buffer when batching is enabled.
Default:
100
. - batchBufferLimit
-
Default:
10000
. - batchTimeout
-
Default:
5000
. - compress
-
Whether data should be compressed when sent.
Default:
false
. - transacted
-
Whether to use transacted channels.
Default:
false
. - deliveryMode
-
Delivery mode.
Default:
PERSISTENT
. - prefix
-
A prefix to be added to the name of the
destination
exchange.Default: "".
- requestHeaderPatterns
-
The request headers to be transported.
Default:
[STANDARD_REQUEST_HEADERS,'*']
. - replyHeaderPatterns
-
The reply headers to be transported.
Default:
[STANDARD_REPLY_HEADERS,'*']
.
Note
|
In the case of RabbitMQ, content type headers can be set by external applications. Spring Cloud Stream supports them as part of an extended internal protocol used for any type of transport (including transports, such as Kafka, that do not normally support headers). |
Dead-Letter Queue Processing
Because it can’t be anticipated how users would want to dispose of dead-lettered messages, the framework does not provide any standard mechanism to handle them.
If the reason for the dead-lettering is transient, you may wish to route the messages back to the original queue.
However, if the problem is a permanent issue, that could cause an infinite loop.
The following spring-boot
application is an example of how to route those messages back to the original queue, but moves them to a third "parking lot" queue after three attempts.
The second example utilizes the RabbitMQ Delayed Message Exchange to introduce a delay to the requeued message.
In this example, the delay increases for each attempt.
These examples use a @RabbitListener
to receive messages from the DLQ, you could also use RabbitTemplate.receive()
in a batch process.
The examples assume the original destination is so8400in
and the consumer group is so8400
.
Non-Partitioned Destinations
The first two examples are when the destination is not partitioned.
@SpringBootApplication
public class ReRouteDlqApplication {
private static final String ORIGINAL_QUEUE = "so8400in.so8400";
private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
private static final String X_RETRIES_HEADER = "x-retries";
public static void main(String[] args) throws Exception {
ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
System.out.println("Hit enter to terminate");
System.in.read();
context.close();
}
@Autowired
private RabbitTemplate rabbitTemplate;
@RabbitListener(queues = DLQ)
public void rePublish(Message failedMessage) {
Integer retriesHeader = (Integer) failedMessage.getMessageProperties().getHeaders().get(X_RETRIES_HEADER);
if (retriesHeader == null) {
retriesHeader = Integer.valueOf(0);
}
if (retriesHeader < 3) {
failedMessage.getMessageProperties().getHeaders().put(X_RETRIES_HEADER, retriesHeader + 1);
this.rabbitTemplate.send(ORIGINAL_QUEUE, failedMessage);
}
else {
this.rabbitTemplate.send(PARKING_LOT, failedMessage);
}
}
@Bean
public Queue parkingLot() {
return new Queue(PARKING_LOT);
}
}
@SpringBootApplication
public class ReRouteDlqApplication {
private static final String ORIGINAL_QUEUE = "so8400in.so8400";
private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
private static final String X_RETRIES_HEADER = "x-retries";
private static final String DELAY_EXCHANGE = "dlqReRouter";
public static void main(String[] args) throws Exception {
ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
System.out.println("Hit enter to terminate");
System.in.read();
context.close();
}
@Autowired
private RabbitTemplate rabbitTemplate;
@RabbitListener(queues = DLQ)
public void rePublish(Message failedMessage) {
Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
if (retriesHeader == null) {
retriesHeader = Integer.valueOf(0);
}
if (retriesHeader < 3) {
headers.put(X_RETRIES_HEADER, retriesHeader + 1);
headers.put("x-delay", 5000 * retriesHeader);
this.rabbitTemplate.send(DELAY_EXCHANGE, ORIGINAL_QUEUE, failedMessage);
}
else {
this.rabbitTemplate.send(PARKING_LOT, failedMessage);
}
}
@Bean
public DirectExchange delayExchange() {
DirectExchange exchange = new DirectExchange(DELAY_EXCHANGE);
exchange.setDelayed(true);
return exchange;
}
@Bean
public Binding bindOriginalToDelay() {
return BindingBuilder.bind(new Queue(ORIGINAL_QUEUE)).to(delayExchange()).with(ORIGINAL_QUEUE);
}
@Bean
public Queue parkingLot() {
return new Queue(PARKING_LOT);
}
}
Partitioned Destinations
With partitioned destinations, there is one DLQ for all partitions and we determine the original queue from the headers.
republishToDlq=false
When republishToDlq
is false
, RabbitMQ publishes the message to the DLX/DLQ with an x-death
header containing information about the original destination.
@SpringBootApplication
public class ReRouteDlqApplication {
private static final String ORIGINAL_QUEUE = "so8400in.so8400";
private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
private static final String X_DEATH_HEADER = "x-death";
private static final String X_RETRIES_HEADER = "x-retries";
public static void main(String[] args) throws Exception {
ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
System.out.println("Hit enter to terminate");
System.in.read();
context.close();
}
@Autowired
private RabbitTemplate rabbitTemplate;
@SuppressWarnings("unchecked")
@RabbitListener(queues = DLQ)
public void rePublish(Message failedMessage) {
Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
if (retriesHeader == null) {
retriesHeader = Integer.valueOf(0);
}
if (retriesHeader < 3) {
headers.put(X_RETRIES_HEADER, retriesHeader + 1);
List<Map<String, ?>> xDeath = (List<Map<String, ?>>) headers.get(X_DEATH_HEADER);
String exchange = (String) xDeath.get(0).get("exchange");
List<String> routingKeys = (List<String>) xDeath.get(0).get("routing-keys");
this.rabbitTemplate.send(exchange, routingKeys.get(0), failedMessage);
}
else {
this.rabbitTemplate.send(PARKING_LOT, failedMessage);
}
}
@Bean
public Queue parkingLot() {
return new Queue(PARKING_LOT);
}
}
republishToDlq=true
When republishToDlq
is true
, the republishing recoverer adds the original exchange and routing key to headers.
@SpringBootApplication
public class ReRouteDlqApplication {
private static final String ORIGINAL_QUEUE = "so8400in.so8400";
private static final String DLQ = ORIGINAL_QUEUE + ".dlq";
private static final String PARKING_LOT = ORIGINAL_QUEUE + ".parkingLot";
private static final String X_RETRIES_HEADER = "x-retries";
private static final String X_ORIGINAL_EXCHANGE_HEADER = RepublishMessageRecoverer.X_ORIGINAL_EXCHANGE;
private static final String X_ORIGINAL_ROUTING_KEY_HEADER = RepublishMessageRecoverer.X_ORIGINAL_ROUTING_KEY;
public static void main(String[] args) throws Exception {
ConfigurableApplicationContext context = SpringApplication.run(ReRouteDlqApplication.class, args);
System.out.println("Hit enter to terminate");
System.in.read();
context.close();
}
@Autowired
private RabbitTemplate rabbitTemplate;
@RabbitListener(queues = DLQ)
public void rePublish(Message failedMessage) {
Map<String, Object> headers = failedMessage.getMessageProperties().getHeaders();
Integer retriesHeader = (Integer) headers.get(X_RETRIES_HEADER);
if (retriesHeader == null) {
retriesHeader = Integer.valueOf(0);
}
if (retriesHeader < 3) {
headers.put(X_RETRIES_HEADER, retriesHeader + 1);
String exchange = (String) headers.get(X_ORIGINAL_EXCHANGE_HEADER);
String originalRoutingKey = (String) headers.get(X_ORIGINAL_ROUTING_KEY_HEADER);
this.rabbitTemplate.send(exchange, originalRoutingKey, failedMessage);
}
else {
this.rabbitTemplate.send(PARKING_LOT, failedMessage);
}
}
@Bean
public Queue parkingLot() {
return new Queue(PARKING_LOT);
}
}
Appendices
Appendix A: Building
Basic Compile and Test
To build the source you will need to install JDK 1.7.
The build uses the Maven wrapper so you don’t have to install a specific version of Maven. To enable the tests for Redis, Rabbit, and Kafka bindings you should have those servers running before building. See below for more information on running the servers.
The main build command is
$ ./mvnw clean install
You can also add '-DskipTests' if you like, to avoid running the tests.
Note
|
You can also install Maven (>=3.3.3) yourself and run the mvn command
in place of ./mvnw in the examples below. If you do that you also
might need to add -P spring if your local Maven settings do not
contain repository declarations for spring pre-release artifacts.
|
Note
|
Be aware that you might need to increase the amount of memory
available to Maven by setting a MAVEN_OPTS environment variable with
a value like -Xmx512m -XX:MaxPermSize=128m . We try to cover this in
the .mvn configuration, so if you find you have to do it to make a
build succeed, please raise a ticket to get the settings added to
source control.
|
The projects that require middleware generally include a
docker-compose.yml
, so consider using
Docker Compose to run the middeware servers
in Docker containers. See the README in the
scripts demo
repository for specific instructions about the common cases of mongo,
rabbit and redis.
Documentation
There is a "full" profile that will generate documentation.
Working with the code
If you don’t have an IDE preference we would recommend that you use Spring Tools Suite or Eclipse when working with the code. We use the m2eclipe eclipse plugin for maven support. Other IDEs and tools should also work without issue.
Importing into eclipse with m2eclipse
We recommend the m2eclipe eclipse plugin when working with eclipse. If you don’t already have m2eclipse installed it is available from the "eclipse marketplace".
Unfortunately m2e does not yet support Maven 3.3, so once the projects
are imported into Eclipse you will also need to tell m2eclipse to use
the .settings.xml
file for the projects. If you do not do this you
may see many different errors related to the POMs in the
projects. Open your Eclipse preferences, expand the Maven
preferences, and select User Settings. In the User Settings field
click Browse and navigate to the Spring Cloud project you imported
selecting the .settings.xml
file in that project. Click Apply and
then OK to save the preference changes.
Note
|
Alternatively you can copy the repository settings from .settings.xml into your own ~/.m2/settings.xml .
|
Importing into eclipse without m2eclipse
If you prefer not to use m2eclipse you can generate eclipse project metadata using the following command:
$ ./mvnw eclipse:eclipse
The generated eclipse projects can be imported by selecting import existing projects
from the file
menu.
[[contributing]
== Contributing
Spring Cloud is released under the non-restrictive Apache 2.0 license, and follows a very standard Github development process, using Github tracker for issues and merging pull requests into master. If you want to contribute even something trivial please do not hesitate, but follow the guidelines below.
Sign the Contributor License Agreement
Before we accept a non-trivial patch or pull request we will need you to sign the contributor’s agreement. Signing the contributor’s agreement does not grant anyone commit rights to the main repository, but it does mean that we can accept your contributions, and you will get an author credit if we do. Active contributors might be asked to join the core team, and given the ability to merge pull requests.
Code Conventions and Housekeeping
None of these is essential for a pull request, but they will all help. They can also be added after the original pull request but before a merge.
-
Use the Spring Framework code format conventions. If you use Eclipse you can import formatter settings using the
eclipse-code-formatter.xml
file from the Spring Cloud Build project. If using IntelliJ, you can use the Eclipse Code Formatter Plugin to import the same file. -
Make sure all new
.java
files to have a simple Javadoc class comment with at least an@author
tag identifying you, and preferably at least a paragraph on what the class is for. -
Add the ASF license header comment to all new
.java
files (copy from existing files in the project) -
Add yourself as an
@author
to the .java files that you modify substantially (more than cosmetic changes). -
Add some Javadocs and, if you change the namespace, some XSD doc elements.
-
A few unit tests would help a lot as well — someone has to do it.
-
If no-one else is using your branch, please rebase it against the current master (or other target branch in the main project).
-
When writing a commit message please follow these conventions, if you are fixing an existing issue please add
Fixes gh-XXXX
at the end of the commit message (where XXXX is the issue number).
Spring Cloud Bus
Spring Cloud Bus links nodes of a distributed system with a lightweight message broker. This can then be used to broadcast state changes (e.g. configuration changes) or other management instructions. A key idea is that the Bus is like a distributed Actuator for a Spring Boot application that is scaled out, but it can also be used as a communication channel between apps. The only implementation currently is with an AMQP broker as the transport, but the same basic feature set (and some more depending on the transport) is on the roadmap for other transports.
Note
|
Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. |
Quick Start
Spring Cloud Bus works by adding Spring Boot autconfiguration if it detects itself on the classpath. All you need to do to enable the bus is to add spring-cloud-starter-bus-amqp
or spring-cloud-starter-bus-kafka
to your dependency management and Spring Cloud takes care of the rest. Make sure the broker (RabbitMQ or Kafka) is available and configured: running on localhost you shouldn’t have to do anything, but if you are running remotely use Spring Cloud Connectors, or Spring Boot conventions to define the broker credentials, e.g. for Rabbit
spring: rabbitmq: host: mybroker.com port: 5672 username: user password: secret
The bus currently supports sending messages to all nodes listening or all nodes for a particular service (as defined by Eureka). More selector criteria may be added in the future (ie. only service X nodes in data center Y, etc…). There are also some http endpoints under the /bus/*
actuator namespace. There are currently two implemented. The first, /bus/env
, sends key/value pairs to update each node’s Spring Environment. The second, /bus/refresh
, will reload each application’s configuration, just as if they had all been pinged on their /refresh
endpoint.
Note
|
The Bus starters cover Rabbit and Kafka, because those are the two most common implementations, but Spring Cloud Stream is quite flexible and binder will work combined with spring-cloud-bus .
|
Addressing an Instance
The HTTP endpoints accept a "destination" parameter, e.g. "/bus/refresh?destination=customers:9000", where the destination is an ApplicationContext
ID. If the ID is owned by an instance on the Bus then it will process the message and all other instances will ignore it. Spring Boot sets the ID for you in the ContextIdApplicationContextInitializer
to a combination of the spring.application.name
, active profiles and server.port
by default.
Addressing all instances of a service
The "destination" parameter is used in a Spring PathMatcher
(with the path separator as a colon :
) to determine if an instance will process the message. Using the example from above, "/bus/refresh?destination=customers:**" will target all instances of the "customers" service regardless of the profiles and ports set as the ApplicationContext
ID.
Application Context ID must be unique
The bus tries to eliminate processing an event twice, once from the original ApplicationEvent
and once from the queue. To do this, it checks the sending application context id againts the current application context id. If multiple instances of a service have the same application context id, events will not be processed. Running on a local machine, each service will be on a different port and that will be part of the application context id. Cloud Foundry supplies an index to differentiate. To ensure that the application context id is the unique, set spring.application.index
to something unique for each instance of a service. For example, in lattice, set spring.application.index=${INSTANCE_INDEX}
in application.properties (or bootstrap.properties if using configserver).
Customizing the Message Broker
Spring Cloud Bus uses
Spring Cloud Stream to
broadcast the messages so to get messages to flow you only need to
include the binder implementation of your choice in the
classpath. There are convenient starters specifically for the bus with
AMQP (RabbitMQ) and Kafka
(spring-cloud-starter-bus-[amqp,kafka]
). Generally speaking
Spring Cloud Stream relies on Spring Boot autoconfiguration
conventions for configuring middleware, so for instance the AMQP
broker address can be changed with spring.rabbitmq.*
configuration properties. Spring Cloud Bus has a handful of native
configuration properties in spring.cloud.bus.*
(e.g. spring.cloud.bus.destination
is the name of the topic to use
the the externall middleware). Normally the defaults will suffice.
To lean more about how to customize the message broker settings consult the Spring Cloud Stream documentation.
Tracing Bus Events
Bus events (subclasses of RemoteApplicationEvent
) can be traced by
setting spring.cloud.bus.trace.enabled=true
. If you do this then the
Spring Boot TraceRepository
(if it is present) will show each event
sent and all the acks from each service instance. Example (from the
/trace
endpoint):
{
"timestamp": "2015-11-26T10:24:44.411+0000",
"info": {
"signal": "spring.cloud.bus.ack",
"type": "RefreshRemoteApplicationEvent",
"id": "c4d374b7-58ea-4928-a312-31984def293b",
"origin": "stores:8081",
"destination": "*:**"
}
},
{
"timestamp": "2015-11-26T10:24:41.864+0000",
"info": {
"signal": "spring.cloud.bus.sent",
"type": "RefreshRemoteApplicationEvent",
"id": "c4d374b7-58ea-4928-a312-31984def293b",
"origin": "customers:9000",
"destination": "*:**"
}
},
{
"timestamp": "2015-11-26T10:24:41.862+0000",
"info": {
"signal": "spring.cloud.bus.ack",
"type": "RefreshRemoteApplicationEvent",
"id": "c4d374b7-58ea-4928-a312-31984def293b",
"origin": "customers:9000",
"destination": "*:**"
}
}
This trace shows that a RefreshRemoteApplicationEvent
was sent from
customers:9000
, broadcast to all services, and it was received
(acked) by customers:9000
and stores:8081
.
To handle the ack signals yourself you could add an @EventListener
for the AckRemoteApplicationEvent
and SentApplicationEvent
types
to your app (and enable tracing). Or you could tap into the
TraceRepository
and mine the data from there.
Note
|
Any Bus application can trace acks, but sometimes it will be useful to do this in a central service that can do more complex queries on the data. Or forward it to a specialized tracing service. |
Broadcasting Your Own Events
The Bus can carry any event of type RemoteApplicationEvent
, but the
default transport is JSON and the deserializer needs to know which
types are going to be used ahead of time. To register a new type it
needs to be in a subpackage of org.springframework.cloud.bus.event
.
To customise the event name you can use @JsonTypeName
on your custom class
or rely on the default strategy which is to use the simple name of the class.
Note that both the producer and the consumer will need access to the class
definition.
Registering events in custom packages
If you cannot or don’t want to use a subpackage of org.springframework.cloud.bus.event
for your custom events, you must specify which packages to scan for events of
type RemoteApplicationEvent
using @RemoteApplicationEventScan
. Packages
specified with @RemoteApplicationEventScan
include subpackages.
For example, if you have a custom event called FooEvent
:
package com.acme;
public class FooEvent extends RemoteApplicationEvent {
...
}
you can register this event with the deserializer in the following way:
package com.acme;
@Configuration
@RemoteApplicationEventScan
public class BusConfiguration {
...
}
Without specifying a value, the package of the class where @RemoteApplicationEventScan
is used will be registered. In this example com.acme
will be registered using the
package of BusConfiguration
.
You can also explicitly specify the packages to scan using the value
, basePackages
or
basePackageClasses
properties on @RemoteApplicationEventScan
. For example:
package com.acme;
@Configuration
//@RemoteApplicationEventScan({"com.acme", "foo.bar"})
//@RemoteApplicationEventScan(basePackages = {"com.acme", "foo.bar", "fizz.buzz"})
@RemoteApplicationEventScan(basePackageClasses = BusConfiguration.class)
public class BusConfiguration {
...
}
All examples of @RemoteApplicationEventScan
above are equivalent,
in that the com.acme
package will be registered by explicitly specifying the
packages on @RemoteApplicationEventScan
. Note, you can specify multiple base
packages to scan.
Spring Cloud Sleuth
Adrian Cole, Spencer Gibb, Marcin Grzejszczak, Dave Syer
Camden.SR7
Spring Cloud Sleuth implements a distributed tracing solution for Spring Cloud.
Terminology
Spring Cloud Sleuth borrows Dapper’s terminology.
Span: The basic unit of work. For example, sending an RPC is a new span, as is sending a response to an RPC. Span’s are identified by a unique 64-bit ID for the span and another 64-bit ID for the trace the span is a part of. Spans also have other data, such as descriptions, timestamped events, key-value annotations (tags), the ID of the span that caused them, and process ID’s (normally IP address).
Spans are started and stopped, and they keep track of their timing information. Once you create a span, you must stop it at some point in the future.
Tip
|
The initial span that starts a trace is called a root span . The value of span id
of that span is equal to trace id.
|
Trace: A set of spans forming a tree-like structure. For example, if you are running a distributed big-data store, a trace might be formed by a put request.
Annotation: is used to record existence of an event in time. Some of the core annotations used to define the start and stop of a request are:
-
cs - Client Sent - The client has made a request. This annotation depicts the start of the span.
-
sr - Server Received - The server side got the request and will start processing it. If one subtracts the cs timestamp from this timestamp one will receive the network latency.
-
ss - Server Sent - Annotated upon completion of request processing (when the response got sent back to the client). If one subtracts the sr timestamp from this timestamp one will receive the time needed by the server side to process the request.
-
cr - Client Received - Signifies the end of the span. The client has successfully received the response from the server side. If one subtracts the cs timestamp from this timestamp one will receive the whole time needed by the client to receive the response from the server.
Visualization of what Span and Trace will look in a system together with the Zipkin annotations:
Each color of a note signifies a span (7 spans - from A to G). If you have such information in the note:
Trace Id = X
Span Id = D
Client Sent
That means that the current span has Trace-Id set to X, Span-Id set to D. It also has emitted Client Sent event.
This is how the visualization of the parent / child relationship of spans would look like:
Purpose
In the following sections the example from the image above will be taken into consideration.
Distributed tracing with Zipkin
Altogether there are 7 spans . If you go to traces in Zipkin you will see this number in the second trace:
However if you pick a particular trace then you will see 4 spans:
Note
|
When picking a particular trace you will see merged spans. That means that if there were 2 spans sent to Zipkin with Server Received and Server Sent / Client Received and Client Sent annotations then they will presented as a single span. |
Why is there a difference between the 7 and 4 spans in this case?
-
2 spans come from
http:/start
span. It has the Server Received (SR) and Server Sent (SS) annotations. -
2 spans come from the RPC call from
service1
toservice2
to thehttp:/foo
endpoint. It has the Client Sent (CS) and Client Received (CR) annotations onservice1
side. It also has Server Received (SR) and Server Sent (SS) annotations on theservice2
side. Physically there are 2 spans but they form 1 logical span related to an RPC call. -
2 spans come from the RPC call from
service2
toservice3
to thehttp:/bar
endpoint. It has the Client Sent (CS) and Client Received (CR) annotations onservice2
side. It also has Server Received (SR) and Server Sent (SS) annotations on theservice3
side. Physically there are 2 spans but they form 1 logical span related to an RPC call. -
2 spans come from the RPC call from
service2
toservice4
to thehttp:/baz
endpoint. It has the Client Sent (CS) and Client Received (CR) annotations onservice2
side. It also has Server Received (SR) and Server Sent (SS) annotations on theservice4
side. Physically there are 2 spans but they form 1 logical span related to an RPC call.
So if we count the physical spans we have 1 from http:/start
, 2 from service1
calling service2
, 2 form service2
calling service3
and 2 from service2
calling service4
. Altogether 7 spans.
Logically we see the information of Total Spans: 4 because we have 1 span related to the incoming request
to service1
and 3 spans related to RPC calls.
Visualizing errors
Zipkin allows you to visualize errors in your trace. When an exception was thrown and wasn’t caught then we’re setting proper tags on the span which Zipkin can properly colorize. You could see in the list of traces one trace that was in red color. That’s because there was an exception thrown.
If you click that trace then you’ll see a similar picture
Then if you click on one of the spans you’ll see the following
As you can see you can easily see the reason for an error and the whole stacktrace related to it.
Live examples
The dependency graph in Zipkin would look like this:
Log correlation
When grepping the logs of those four applications by trace id equal to e.g. 2485ec27856c56f4
one would get the following:
service1.log:2016-02-26 11:15:47.561 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Hello from service1. Calling service2
service2.log:2016-02-26 11:15:47.710 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Hello from service2. Calling service3 and then service4
service3.log:2016-02-26 11:15:47.895 INFO [service3,2485ec27856c56f4,1210be13194bfe5,true] 68060 --- [nio-8083-exec-1] i.s.c.sleuth.docs.service3.Application : Hello from service3
service2.log:2016-02-26 11:15:47.924 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service3 [Hello from service3]
service4.log:2016-02-26 11:15:48.134 INFO [service4,2485ec27856c56f4,1b1845262ffba49d,true] 68061 --- [nio-8084-exec-1] i.s.c.sleuth.docs.service4.Application : Hello from service4
service2.log:2016-02-26 11:15:48.156 INFO [service2,2485ec27856c56f4,9aa10ee6fbde75fa,true] 68059 --- [nio-8082-exec-1] i.s.c.sleuth.docs.service2.Application : Got response from service4 [Hello from service4]
service1.log:2016-02-26 11:15:48.182 INFO [service1,2485ec27856c56f4,2485ec27856c56f4,true] 68058 --- [nio-8081-exec-1] i.s.c.sleuth.docs.service1.Application : Got response from service2 [Hello from service2, response from service3 [Hello from service3] and from service4 [Hello from service4]]
If you’re using a log aggregating tool like Kibana, Splunk etc. you can order the events that took place. An example of Kibana would look like this:
If you want to use Logstash here is the Grok pattern for Logstash:
filter {
# pattern matching logback pattern
grok {
match => { "message" => "%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
}
}
Note
|
If you want to use Grok together with the logs from Cloud Foundry you have to use this pattern: |
filter {
# pattern matching logback pattern
grok {
match => { "message" => "(?m)OUT\s+%{TIMESTAMP_ISO8601:timestamp}\s+%{LOGLEVEL:severity}\s+\[%{DATA:service},%{DATA:trace},%{DATA:span},%{DATA:exportable}\]\s+%{DATA:pid}\s+---\s+\[%{DATA:thread}\]\s+%{DATA:class}\s+:\s+%{GREEDYDATA:rest}" }
}
}
JSON Logback with Logstash
Often you do not want to store your logs in a text file but in a JSON file that Logstash can immediately pick. To do that you have to do the following (for readability
we’re passing the dependencies in the groupId:artifactId:version
notation.
Dependencies setup
-
Ensure that Logback is on the classpath (
ch.qos.logback:logback-core
) -
Add Logstash Logback encode - example for version
4.6
:net.logstash.logback:logstash-logback-encoder:4.6
Logback setup
Below you can find an example of a Logback configuration (file named logback-spring.xml) that:
-
logs information from the application in a JSON format to a
build/${spring.application.name}.json
file -
has commented out two additional appenders - console and standard log file
-
has the same logging pattern as the one presented in the previous section
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
​
<springProperty scope="context" name="springAppName" source="spring.application.name"/>
<!-- Example for logging into the build folder of your project -->
<property name="LOG_FILE" value="${BUILD_FOLDER:-build}/${springAppName}"/>​
<!-- You can override this to have a custom pattern -->
<property name="CONSOLE_LOG_PATTERN"
value="%clr(%d{yyyy-MM-dd HH:mm:ss.SSS}){faint} %clr(${LOG_LEVEL_PATTERN:-%5p}) %clr(${PID:- }){magenta} %clr(---){faint} %clr([%15.15t]){faint} %clr(%-40.40logger{39}){cyan} %clr(:){faint} %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/>
<!-- Appender to log to console -->
<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
<filter class="ch.qos.logback.classic.filter.ThresholdFilter">
<!-- Minimum logging level to be presented in the console logs-->
<level>DEBUG</level>
</filter>
<encoder>
<pattern>${CONSOLE_LOG_PATTERN}</pattern>
<charset>utf8</charset>
</encoder>
</appender>
<!-- Appender to log to file -->​
<appender name="flatfile" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${LOG_FILE}</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<fileNamePattern>${LOG_FILE}.%d{yyyy-MM-dd}.gz</fileNamePattern>
<maxHistory>7</maxHistory>
</rollingPolicy>
<encoder>
<pattern>${CONSOLE_LOG_PATTERN}</pattern>
<charset>utf8</charset>
</encoder>
</appender>
​
<!-- Appender to log to file in a JSON format -->
<appender name="logstash" class="ch.qos.logback.core.rolling.RollingFileAppender">
<file>${LOG_FILE}.json</file>
<rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
<fileNamePattern>${LOG_FILE}.json.%d{yyyy-MM-dd}.gz</fileNamePattern>
<maxHistory>7</maxHistory>
</rollingPolicy>
<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">
<providers>
<timestamp>
<timeZone>UTC</timeZone>
</timestamp>
<pattern>
<pattern>
{
"severity": "%level",
"service": "${springAppName:-}",
"trace": "%X{X-B3-TraceId:-}",
"span": "%X{X-B3-SpanId:-}",
"parent": "%X{X-B3-ParentSpanId:-}",
"exportable": "%X{X-Span-Export:-}",
"pid": "${PID:-}",
"thread": "%thread",
"class": "%logger{40}",
"rest": "%message"
}
</pattern>
</pattern>
</providers>
</encoder>
</appender>
​
<root level="INFO">
<appender-ref ref="console"/>
<!-- uncomment this to have also JSON logs -->
<!--<appender-ref ref="logstash"/>-->
<!--<appender-ref ref="flatfile"/>-->
</root>
</configuration>
Note
|
If you’re using a custom logback-spring.xml then you have to pass the spring.application.name in
bootstrap instead of application property file. Otherwise your custom logback file won’t read the property properly.
|
Adding to the project
Only Sleuth (log correlation)
If you want to profit only from Spring Cloud Sleuth without the Zipkin integration just add
the spring-cloud-starter-sleuth
module to your project.
<dependencyManagement> (1)
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency> (2)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-starter-sleuth
dependencyManagement { (1)
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:Brixton.RELEASE"
}
}
dependencies { (2)
compile "org.springframework.cloud:spring-cloud-starter-sleuth"
}
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-starter-sleuth
Sleuth with Zipkin via HTTP
If you want both Sleuth and Zipkin just add the spring-cloud-starter-zipkin
dependency.
<dependencyManagement> (1)
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency> (2)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zipkin</artifactId>
</dependency>
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-starter-zipkin
dependencyManagement { (1)
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:Brixton.RELEASE"
}
}
dependencies { (2)
compile "org.springframework.cloud:spring-cloud-starter-zipkin"
}
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-starter-zipkin
Sleuth with Zipkin via Spring Cloud Stream
If you want both Sleuth and Zipkin just add the spring-cloud-sleuth-stream
dependency.
<dependencyManagement> (1)
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency> (2)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-sleuth-stream</artifactId>
</dependency>
<dependency> (3)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>
<!-- EXAMPLE FOR RABBIT BINDING -->
<dependency> (4)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-sleuth-stream
-
Add the dependency to
spring-cloud-starter-sleuth
- that way all dependant dependencies will be downloaded -
Add a binder (e.g. Rabbit binder) to tell Spring Cloud Stream what it should bind to
dependencyManagement { (1)
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:Brixton.RELEASE"
}
}
dependencies {
compile "org.springframework.cloud:spring-cloud-sleuth-stream" (2)
compile "org.springframework.cloud:spring-cloud-starter-sleuth" (3)
// Example for Rabbit binding
compile "org.springframework.cloud:spring-cloud-stream-binder-rabbit" (4)
}
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-sleuth-stream
-
Add the dependency to
spring-cloud-starter-sleuth
- that way all dependant dependencies will be downloaded -
Add a binder (e.g. Rabbit binder) to tell Spring Cloud Stream what it should bind to
Spring Cloud Sleuth Stream Zipkin Collector
If you want to start a Spring Cloud Sleuth Stream Zipkin collector just add the spring-cloud-sleuth-zipkin-stream
dependency
<dependencyManagement> (1)
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.RELEASE</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency> (2)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-sleuth-zipkin-stream</artifactId>
</dependency>
<dependency> (3)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>
<!-- EXAMPLE FOR RABBIT BINDING -->
<dependency> (4)
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-binder-rabbit</artifactId>
</dependency>
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-sleuth-zipkin-stream
-
Add the dependency to
spring-cloud-starter-sleuth
- that way all dependant dependencies will be downloaded -
Add a binder (e.g. Rabbit binder) to tell Spring Cloud Stream what it should bind to
dependencyManagement { (1)
imports {
mavenBom "org.springframework.cloud:spring-cloud-dependencies:Brixton.RELEASE"
}
}
dependencies {
compile "org.springframework.cloud:spring-cloud-sleuth-zipkin-stream" (2)
compile "org.springframework.cloud:spring-cloud-starter-sleuth" (3)
// Example for Rabbit binding
compile "org.springframework.cloud:spring-cloud-stream-binder-rabbit" (4)
}
-
In order not to pick versions by yourself it’s much better if you add the dependency management via the Spring BOM
-
Add the dependency to
spring-cloud-sleuth-zipkin-stream
-
Add the dependency to
spring-cloud-starter-sleuth
- that way all dependant dependencies will be downloaded -
Add a binder (e.g. Rabbit binder) to tell Spring Cloud Stream what it should bind to
and then just annotate your main class with @EnableZipkinStreamServer
annotation:
package example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.sleuth.zipkin.stream.EnableZipkinStreamServer;
@SpringBootApplication
@EnableZipkinStreamServer
public class ZipkinStreamServerApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(ZipkinStreamServerApplication.class, args);
}
}
Additional resources
Features
-
Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator. Example logs:
2016-02-02 15:30:57.902 INFO [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ... 2016-02-02 15:30:58.372 ERROR [bar,6bfd228dc00d216b,6bfd228dc00d216b,false] 23030 --- [nio-8081-exec-3] ... 2016-02-02 15:31:01.936 INFO [bar,46ab0d418373cbc9,46ab0d418373cbc9,false] 23030 --- [nio-8081-exec-4] ...
notice the
[appname,traceId,spanId,exportable]
entries from the MDC:-
spanId - the id of a specific operation that took place
-
appname - the name of the application that logged the span
-
traceId - the id of the latency graph that contains the span
-
exportable - whether the log should be exported to Zipkin or not. When would you like the span not to be exportable? In the case in which you want to wrap some operation in a Span and have it written to the logs only.
-
-
Provides an abstraction over common distributed tracing data models: traces, spans (forming a DAG), annotations, key-value annotations. Loosely based on HTrace, but Zipkin (Dapper) compatible.
-
Sleuth records timing information to aid in latency analysis. Using sleuth, you can pinpoint causes of latency in your applications. Sleuth is written to not log too much, and to not cause your production application to crash.
-
propagates structural data about your call-graph in-band, and the rest out-of-band.
-
includes opinionated instrumentation of layers such as HTTP
-
includes sampling policy to manage volume
-
can report to a Zipkin system for query and visualization
-
-
Instruments common ingress and egress points from Spring applications (servlet filter, async endpoints, rest template, scheduled actions, message channels, zuul filters, feign client).
-
Sleuth includes default logic to join a trace across http or messaging boundaries. For example, http propagation works via Zipkin-compatible request headers. This propagation logic is defined and customized via
SpanInjector
andSpanExtractor
implementations. -
Provides simple metrics of accepted / dropped spans.
-
If
spring-cloud-sleuth-zipkin
then the app will generate and collect Zipkin-compatible traces. By default it sends them via HTTP to a Zipkin server on localhost (port 9411). Configure the location of the service usingspring.zipkin.baseUrl
. -
If
spring-cloud-sleuth-stream
then the app will generate and collect traces via Spring Cloud Stream. Your app automatically becomes a producer of tracer messages that are sent over your broker of choice (e.g. RabbitMQ, Apache Kafka, Redis).
Important
|
If using Zipkin or Stream, configure the percentage of spans exported using spring.sleuth.sampler.percentage
(default 0.1, i.e. 10%). Otherwise you might think that Sleuth is not working cause it’s omitting some spans.
|
Note
|
the SLF4J MDC is always set and logback users will immediately see the trace and span ids in logs per the example
above. Other logging systems have to configure their own formatter to get the same result. The default is
logging.pattern.level set to %5p [${spring.zipkin.service.name:${spring.application.name:-}},%X{X-B3-TraceId:-},%X{X-B3-SpanId:-},%X{X-Span-Export:-}]
(this is a Spring Boot feature for logback users).
This means that if you’re not using SLF4J this pattern WILL NOT be automatically applied.
|
Sampling
In distributed tracing the data volumes can be very high so sampling
can be important (you usually don’t need to export all spans to get a
good picture of what is happening). Spring Cloud Sleuth has a
Sampler
strategy that you can implement to take control of the
sampling algorithm. Samplers do not stop span (correlation) ids from
being generated, but they do prevent the tags and events being
attached and exported. By default you get a strategy that continues to
trace if a span is already active, but new ones are always marked as
non-exportable. If all your apps run with this sampler you will see
traces in logs, but not in any remote store. For testing the default
is often enough, and it probably is all you need if you are only using
the logs (e.g. with an ELK aggregator). If you are exporting span data
to Zipkin or Spring Cloud Stream, there is also an AlwaysSampler
that exports everything and a PercentageBasedSampler
that samples a
fixed fraction of spans.
Note
|
the PercentageBasedSampler is the default if you are using
spring-cloud-sleuth-zipkin or spring-cloud-sleuth-stream . You can
configure the exports using spring.sleuth.sampler.percentage . The passed
value needs to be a double from 0.0 to 1.0 so it’s not a percentage.
For backwards compatibility reasons we’re not changing the property name.
|
A sampler can be installed just by creating a bean definition, e.g:
@Bean
public Sampler defaultSampler() {
return new AlwaysSampler();
}
Instrumentation
Spring Cloud Sleuth instruments all your Spring application
automatically, so you shouldn’t have to do anything to activate
it. The instrumentation is added using a variety of technologies
according to the stack that is available, e.g. for a servlet web
application we use a Filter
, and for Spring Integration we use
ChannelInterceptors
.
You can customize the keys used in span tags. To limit the volume of
span data, by default an HTTP request will be tagged only with a
handful of metadata like the status code, host and URL. You can add
request headers by configuring spring.sleuth.keys.http.headers
(a
list of header names).
Note
|
Remember that tags are only collected and exported if there is a
Sampler that allows it (by default there is not, so there is no
danger of accidentally collecting too much data without configuring
something).
|
Note
|
Currently the instrumentation in Spring Cloud Sleuth is eager - it means that we’re actively trying to pass the tracing context between threads. Also timing events are captured even when sleuth isn’t exporting data to a tracing system. This approach may change in the future towards being lazy on this matter. |
Span lifecycle
You can do the following operations on the Span by means of org.springframework.cloud.sleuth.Tracer interface:
-
start - when you start a span its name is assigned and start timestamp is recorded.
-
close - the span gets finished (the end time of the span is recorded) and if the span is exportable then it will be eligible for collection to Zipkin. The span is also removed from the current thread.
-
continue - a new instance of span will be created whereas it will be a copy of the one that it continues.
-
detach - the span doesn’t get stopped or closed. It only gets removed from the current thread.
-
create with explicit parent - you can create a new span and set an explicit parent to it
Tip
|
Spring creates the instance of Tracer for you. In order to use it all you need is to just autowire it.
|
Creating and closing spans
You can manually create spans by using the Tracer interface.
// Start a span. If there was a span present in this thread it will become
// the `newSpan`'s parent.
Span newSpan = this.tracer.createSpan("calculateTax");
try {
// ...
// You can tag a span
this.tracer.addTag("taxValue", taxValue);
// ...
// You can log an event on a span
newSpan.logEvent("taxCalculated");
} finally {
// Once done remember to close the span. This will allow collecting
// the span to send it to Zipkin
this.tracer.close(newSpan);
}
In this example we could see how to create a new instance of span. Assuming that there already was a span present in this thread then it would become the parent of that span.
Important
|
Always clean after you create a span! Don’t forget to close a span if you want to send it to Zipkin. |
Important
|
If your span contains a name greater than 50 chars, then that name will be truncated to 50 chars. Your names have to be explicit and concrete. Big names lead to latency issues and sometimes even thrown exceptions. |
Continuing spans
Sometimes you don’t want to create a new span but you want to continue one. Example of such a situation might be (of course it all depends on the use-case):
-
AOP - If there was already a span created before an aspect was reached then you might not want to create a new span.
-
Hystrix - executing a Hystrix command is most likely a logical part of the current processing. It’s in fact only a technical implementation detail that you wouldn’t necessarily want to reflect in tracing as a separate being.
The continued instance of span is equal to the one that it continues:
Span continuedSpan = this.tracer.continueSpan(spanToContinue);
assertThat(continuedSpan).isEqualTo(spanToContinue);
To continue a span you can use the Tracer interface.
// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X
Span continuedSpan = this.tracer.continueSpan(initialSpan);
try {
// ...
// You can tag a span
this.tracer.addTag("taxValue", taxValue);
// ...
// You can log an event on a span
continuedSpan.logEvent("taxCalculated");
} finally {
// Once done remember to detach the span. That way you'll
// safely remove it from the current thread without closing it
this.tracer.detach(continuedSpan);
}
Important
|
Always clean after you create a span! Don’t forget to detach a span if some work was done started in one thread (e.g. thread X) and it’s waiting for other threads (e.g. Y, Z) to finish. Then the spans in the threads Y, Z should be detached at the end of their work. When the results are collected the span in thread X should be closed. |
Creating spans with an explicit parent
There is a possibility that you want to start a new span and provide an explicit parent of that span.
Let’s assume that the parent of a span is in one thread and you want to start a new span in another thread. The
startSpan
method of the Tracer
interface is the method you are looking for.
// let's assume that we're in a thread Y and we've received
// the `initialSpan` from thread X. `initialSpan` will be the parent
// of the `newSpan`
Span newSpan = this.tracer.createSpan("calculateCommission", initialSpan);
try {
// ...
// You can tag a span
this.tracer.addTag("commissionValue", commissionValue);
// ...
// You can log an event on a span
newSpan.logEvent("commissionCalculated");
} finally {
// Once done remember to close the span. This will allow collecting
// the span to send it to Zipkin. The tags and events set on the
// newSpan will not be present on the parent
this.tracer.close(newSpan);
}
Important
|
After having created such a span remember to close it. Otherwise you will see a lot of warnings in your logs related to the fact that you have a span present in the current thread other than the one you’re trying to close. What’s worse your spans won’t get closed properly thus will not get collected to Zipkin. |
Naming spans
Picking a span name is not a trivial task. Span name should depict an operation name. The name should be low cardinality (e.g. not include identifiers).
Since there is a lot of instrumentation going on some of the span names will be artificial like:
-
controller-method-name
when received by a Controller with a method nameconrollerMethodName
-
async
for asynchronous operations done via wrappedCallable
andRunnable
. -
@Scheduled
annotated methods will return the simple name of the class.
Fortunately, for the asynchronous processing you can provide explicit naming.
@SpanName annotation
You can do name the span explicitly via the @SpanName
annotation.
@SpanName("calculateTax")
class TaxCountingRunnable implements Runnable {
@Override public void run() {
// perform logic
}
}
In this case, when processed in the following manner:
Runnable runnable = new TraceRunnable(tracer, spanNamer, new TaxCountingRunnable());
Future<?> future = executorService.submit(runnable);
// ... some additional logic ...
future.get();
The span will be named calculateTax
.
toString() method
It’s pretty rare to create separate classes for Runnable
or Callable
. Typically one creates an anonymous
instance of those classes. You can’t annotate such classes thus to override that, if there is no @SpanName
annotation present,
we’re checking if the class has a custom implementation of the toString()
method.
So executing such code:
Runnable runnable = new TraceRunnable(tracer, spanNamer, new Runnable() {
@Override public void run() {
// perform logic
}
@Override public String toString() {
return "calculateTax";
}
});
Future<?> future = executorService.submit(runnable);
// ... some additional logic ...
future.get();
will lead in creating a span named calculateTax
.
Customizations
Thanks to the SpanInjector
and SpanExtractor
you can customize the way spans
are created and propagated.
There are currently two built-in ways to pass tracing information between processes:
-
via Spring Integration
-
via HTTP
Span ids are extracted from Zipkin-compatible (B3) headers (either Message
or HTTP headers), to start or join an existing trace. Trace information is
injected into any outbound requests so the next hop can extract them.
Spring Integration
For Spring Integration these are the beans responsible for creation of a Span from a Message
and filling in the MessageBuilder
with tracing information.
@Bean
public SpanExtractor<Message> messagingSpanExtractor() {
...
}
@Bean
public SpanInjector<MessageBuilder> messagingSpanInjector() {
...
}
You can override them by providing your own implementation and by adding a @Primary
annotation
to your bean definition.
HTTP
For HTTP these are the beans responsible for creation of a Span from a HttpServletRequest
.
@Bean
public SpanExtractor<HttpServletRequest> httpServletRequestSpanExtractor() {
...
}
You can override them by providing your own implementation and by adding a @Primary
annotation
to your bean definition.
Example
Let’s assume that instead of the standard Zipkin compatible tracing HTTP header names you have
-
for trace id -
correlationId
-
for span id -
mySpanId
This is a an example of a SpanExtractor
static class CustomHttpServletRequestSpanExtractor
implements SpanExtractor<HttpServletRequest> {
@Override
public Span joinTrace(HttpServletRequest carrier) {
long traceId = Span.hexToId(carrier.getHeader("correlationId"));
long spanId = Span.hexToId(carrier.getHeader("mySpanId"));
// extract all necessary headers
Span.SpanBuilder builder = Span.builder().traceId(traceId).spanId(spanId);
// build rest of the Span
return builder.build();
}
}
And you could register it like this:
@Bean
@Primary
SpanExtractor<HttpServletRequest> customHttpServletRequestSpanExtractor() {
return new CustomHttpServletRequestSpanExtractor();
}
Spring Cloud Sleuth does not add trace/span related headers to the Http Response for security reasons. If you need the headers then a custom SpanInjector
that injects the headers into the Http Response and a Servlet filter which makes use of this can be added the following way:
static class CustomHttpServletResponseSpanInjector
implements SpanInjector<HttpServletResponse> {
@Override
public void inject(Span span, HttpServletResponse carrier) {
carrier.addHeader(Span.TRACE_ID_NAME, span.traceIdString());
carrier.addHeader(Span.SPAN_ID_NAME, Span.idToHex(span.getSpanId()));
}
}
static class HttpResponseInjectingTraceFilter extends GenericFilterBean {
private final Tracer tracer;
private final SpanInjector<HttpServletResponse> spanInjector;
public HttpResponseInjectingTraceFilter(Tracer tracer, SpanInjector<HttpServletResponse> spanInjector) {
this.tracer = tracer;
this.spanInjector = spanInjector;
}
@Override
public void doFilter(ServletRequest request, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletResponse response = (HttpServletResponse) servletResponse;
Span currentSpan = this.tracer.getCurrentSpan();
this.spanInjector.inject(currentSpan, response);
filterChain.doFilter(request, response);
}
}
And you could register them like this:
@Bean
SpanInjector<HttpServletResponse> customHttpServletResponseSpanInjector() {
return new CustomHttpServletResponseSpanInjector();
}
@Bean
HttpResponseInjectingTraceFilter responseInjectingTraceFilter(Tracer tracer) {
return new HttpResponseInjectingTraceFilter(tracer, customHttpServletResponseSpanInjector());
}
Custom SA tag in Zipkin
Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented.
What you can do is to create a span with the peer.service
tag that will contain a value of the service that you want to call.
Below you can see an example of a call to Redis that is wrapped in such a span.
org.springframework.cloud.sleuth.Span newSpan = tracer.createSpan("redis");
try {
newSpan.tag("redis.op", "get");
newSpan.tag("lc", "redis");
newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_SEND);
// call redis service e.g
// return (SomeObj) redisTemplate.opsForHash().get("MYHASH", someObjKey);
} finally {
newSpan.tag("peer.service", "redisService");
newSpan.tag("peer.ipv4", "1.2.3.4");
newSpan.tag("peer.port", "1234");
newSpan.logEvent(org.springframework.cloud.sleuth.Span.CLIENT_RECV);
tracer.close(newSpan);
}
Important
|
Remember not to add both peer.service tag and the SA tag! You have to add only peer.service .
|
Custom service name
By default Sleuth assumes that when you send a span to Zipkin, you want the span’s service name
to be equal to spring.application.name
value. That’s not always the case though. There
are situations in which you want to explicitly provide a different service name for all spans coming
from your application. To achieve that it’s enough to just pass the following property
to your application to override that value (example for foo
service name):
spring.zipkin.service.name: foo
Customization of reported spans
Before reporting spans to e.g. Zipkin you can be interested in modifying that span in some way.
You can achieve that by using the SpanAdjuster
interface.
Example of usage:
In Sleuth we’re generating spans with a fixed name. Some users want to modify the name depending on values
of tags. Implementation of the SpanAdjuster
interface can be used to alter that name. Example:
@Bean
SpanAdjuster customSpanAdjuster() {
return span -> span.toBuilder().name(scrub(span.getName())).build();
}
This will lead in changing the name of the reported span just before it gets sent to Zipkin.
Important
|
Your SpanReporter should inject the SpanAdjuster and
allow span manipulation before the actual reporting is done.
|
Host locator
In order to define the host that is corresponding to a particular span we need to resolve the host name and port. The default approach is to take it from server properties. If those for some reason are not set then we’re trying to retrieve the host name from the network interfaces.
If you have the discovery client enabled and prefer to retrieve the host address from the registered instance in a service registry then you have to set the property (it’s applicable for both HTTP and Stream based span reporting).
spring.zipkin.locator.discovery.enabled: true
Span Data as Messages
You can accumulate and send span data over
Spring Cloud Stream by
including the spring-cloud-sleuth-stream
jar as a dependency, and
adding a Channel Binder implementation
(e.g. spring-cloud-starter-stream-rabbit
for RabbitMQ or
spring-cloud-starter-stream-kafka
for Kafka). This will
automatically turn your app into a producer of messages with payload
type Spans
.
Zipkin Consumer
There is a special convenience annotation for setting up a message consumer
for the Span data and pushing it into a Zipkin SpanStore
. This application
@SpringBootApplication
@EnableZipkinStreamServer
public class Consumer {
public static void main(String[] args) {
SpringApplication.run(Consumer.class, args);
}
}
will listen for the Span data on whatever transport you provide via a
Spring Cloud Stream Binder
(e.g. include
spring-cloud-starter-stream-rabbit
for RabbitMQ, and similar
starters exist for Redis and Kafka). If you add the following UI dependency
<groupId>io.zipkin.java</groupId>
<artifactId>zipkin-autoconfigure-ui</artifactId>
Then you’ll have your app a Zipkin server, which hosts the UI and api on port 9411.
The default SpanStore
is in-memory (good for demos and getting
started quickly). For a more robust solution you can add MySQL and
spring-boot-starter-jdbc
to your classpath and enable the JDBC
SpanStore
via configuration, e.g.:
spring:
rabbitmq:
host: ${RABBIT_HOST:localhost}
datasource:
schema: classpath:/mysql.sql
url: jdbc:mysql://${MYSQL_HOST:localhost}/test
username: root
password: root
# Switch this on to create the schema on startup:
initialize: true
continueOnError: true
sleuth:
enabled: false
zipkin:
storage:
type: mysql
Note
|
The @EnableZipkinStreamServer is also annotated with
@EnableZipkinServer so the process will also expose the standard
Zipkin server endpoints for collecting spans over HTTP, and for
querying in the Zipkin Web UI.
|
Custom Consumer
A custom consumer can also easily be implemented using
spring-cloud-sleuth-stream
and binding to the SleuthSink
. Example:
@EnableBinding(SleuthSink.class)
@SpringBootApplication(exclude = SleuthStreamAutoConfiguration.class)
@MessageEndpoint
public class Consumer {
@ServiceActivator(inputChannel = SleuthSink.INPUT)
public void sink(Spans input) throws Exception {
// ... process spans
}
}
Note
|
the sample consumer application above explicitly excludes
SleuthStreamAutoConfiguration so it doesn’t send messages to itself,
but this is optional (you might actually want to trace requests into
the consumer app).
|
Metrics
Currently Spring Cloud Sleuth registers very simple metrics related to spans. It’s using the Spring Boot’s metrics support to calculate the number of accepted and dropped spans. Each time a span gets sent to Zipkin the number of accepted spans will increase. If there’s an error then the number of dropped spans will get increased.
Integrations
Runnable and Callable
If you’re wrapping your logic in Runnable
or Callable
it’s enough to wrap those classes in their Sleuth representative.
Example for Runnable
:
Runnable runnable = new Runnable() {
@Override
public void run() {
// do some work
}
@Override
public String toString() {
return "spanNameFromToStringMethod";
}
};
// Manual `TraceRunnable` creation with explicit "calculateTax" Span name
Runnable traceRunnable = new TraceRunnable(tracer, spanNamer, runnable, "calculateTax");
// Wrapping `Runnable` with `Tracer`. The Span name will be taken either from the
// `@SpanName` annotation or from `toString` method
Runnable traceRunnableFromTracer = tracer.wrap(runnable);
Example for Callable
:
Callable<String> callable = new Callable<String>() {
@Override
public String call() throws Exception {
return someLogic();
}
@Override
public String toString() {
return "spanNameFromToStringMethod";
}
};
// Manual `TraceCallable` creation with explicit "calculateTax" Span name
Callable<String> traceCallable = new TraceCallable<>(tracer, spanNamer, callable, "calculateTax");
// Wrapping `Callable` with `Tracer`. The Span name will be taken either from the
// `@SpanName` annotation or from `toString` method
Callable<String> traceCallableFromTracer = tracer.wrap(callable);
That way you will ensure that a new Span is created and closed for each execution.
Hystrix
Custom Concurrency Strategy
We’re registering a custom HystrixConcurrencyStrategy
that wraps all Callable
instances into their Sleuth representative -
the TraceCallable
. The strategy either starts or continues a span depending on the fact whether tracing was already going
on before the Hystrix command was called. To disable the custom Hystrix Concurrency Strategy set the spring.sleuth.hystrix.strategy.enabled
to false
.
Manual Command setting
Assuming that you have the following HystrixCommand
:
HystrixCommand<String> hystrixCommand = new HystrixCommand<String>(setter) {
@Override
protected String run() throws Exception {
return someLogic();
}
};
In order to pass the tracing information you have to wrap the same logic in the Sleuth version of the HystrixCommand
which is the
TraceCommand
:
TraceCommand<String> traceCommand = new TraceCommand<String>(tracer, traceKeys, setter) {
@Override
public String doRun() throws Exception {
return someLogic();
}
};
RxJava
We’re registering a custom RxJavaSchedulersHook
that wraps all Action0
instances into their Sleuth representative -
the TraceAction
. The hook either starts or continues a span depending on the fact whether tracing was already going
on before the Action was scheduled. To disable the custom RxJavaSchedulersHook set the spring.sleuth.rxjava.schedulers.hook.enabled
to false
.
You can define a list of regular expressions for thread names, for which you don’t want a Span to be created. Just provide a comma separated list
of regular expressions in the spring.sleuth.rxjava.schedulers.ignoredthreads
property.
HTTP integration
Features from this section can be disabled by providing the spring.sleuth.web.enabled
property with value equal to false
.
HTTP Filter
Via the TraceFilter
all sampled incoming requests result in creation of a Span. That Span’s name is http:
+ the path to which
the request was sent. E.g. if the request was sent to /foo/bar
then the name will be http:/foo/bar
. You can configure which URIs you would
like to skip via the spring.sleuth.web.skipPattern
property. If you have ManagementServerProperties
on classpath then
its value of contextPath
gets appended to the provided skip pattern.
HandlerInterceptor
Since we want the span names to be precise we’re using a TraceHandlerInterceptor
that either wraps an
existing HandlerInterceptor
or is added directly to the list of existing HandlerInterceptors
. The
TraceHandlerInterceptor
adds a special request attribute to the given HttpServletRequest
. If the
the TraceFilter
doesn’t see this attribute set it will create a "fallback" span which is an additional
span created on the server side so that the trace is presented properly in the UI. Seeing that most likely
signifies that there is a missing instrumentation. In that case please file an issue in Spring Cloud Sleuth.
Async Servlet support
If your controller returns a Callable
or a WebAsyncTask
Spring Cloud Sleuth will continue the existing span instead of creating a new one.
HTTP client integration
Synchronous Rest Template
We’re injecting a RestTemplate
interceptor that ensures that all the tracing information is passed to the requests. Each time a
call is made a new Span is created. It gets closed upon receiving the response. In order to block the synchronous RestTemplate
features
just set spring.sleuth.web.client.enabled
to false
.
Important
|
You have to register RestTemplate as a bean so that the interceptors will get injected.
If you create a RestTemplate instance with a new keyword then the instrumentation WILL NOT work.
|
Asynchronous Rest Template
Important
|
A traced version of an AsyncRestTemplate bean is registered for you out of the box. If you
have your own bean you have to wrap it in a TraceAsyncRestTemplate representation. The best solution
is to only customize the ClientHttpRequestFactory and / or AsyncClientHttpRequestFactory .
If you have your own AsyncRestTemplate and you don’t wrap it your calls WILL NOT GET TRACED.
|
Custom instrumentation is set to create and close Spans upon sending and receiving requests. You can customize the ClientHttpRequestFactory
and the AsyncClientHttpRequestFactory
by registering your beans. Remember to use tracing compatible implementations (e.g. don’t forget to
wrap ThreadPoolTaskScheduler
in a TraceAsyncListenableTaskExecutor
). Example of custom request factories:
@EnableAutoConfiguration
@Configuration
public static class TestConfiguration {
@Bean
ClientHttpRequestFactory mySyncClientFactory() {
return new MySyncClientHttpRequestFactory();
}
@Bean
AsyncClientHttpRequestFactory myAsyncClientFactory() {
return new MyAsyncClientHttpRequestFactory();
}
}
To block the AsyncRestTemplate
features set spring.sleuth.web.async.client.enabled
to false
.
To disable creation of the default TraceAsyncClientHttpRequestFactoryWrapper
set spring.sleuth.web.async.client.factory.enabled
to false
. If you don’t want to create AsyncRestClient
at all set spring.sleuth.web.async.client.template.enabled
to false
.
Multiple Asynchronous Rest Templates
Sometimes you need to use multiple implementations of Asynchronous Rest Template. In the following snippet you
can see an example of how to set up such a custom AsyncRestTemplate
.
@Configuration
@EnableAutoConfiguration
static class Config {
@Autowired Tracer tracer;
@Autowired HttpTraceKeysInjector httpTraceKeysInjector;
@Autowired SpanInjector<HttpRequest> spanInjector;
@Bean(name = "customAsyncRestTemplate")
public AsyncRestTemplate traceAsyncRestTemplate(@Qualifier("customHttpRequestFactoryWrapper")
TraceAsyncClientHttpRequestFactoryWrapper wrapper) {
return new TraceAsyncRestTemplate(wrapper, this.tracer);
}
@Bean(name = "customHttpRequestFactoryWrapper")
public TraceAsyncClientHttpRequestFactoryWrapper traceAsyncClientHttpRequestFactory() {
return new TraceAsyncClientHttpRequestFactoryWrapper(this.tracer,
this.spanInjector,
asyncClientFactory(),
clientHttpRequestFactory(),
this.httpTraceKeysInjector);
}
private ClientHttpRequestFactory clientHttpRequestFactory() {
ClientHttpRequestFactory clientHttpRequestFactory = new CustomClientHttpRequestFactory();
//CUSTOMIZE HERE
return clientHttpRequestFactory;
}
private AsyncClientHttpRequestFactory asyncClientFactory() {
AsyncClientHttpRequestFactory factory = new CustomAsyncClientHttpRequestFactory();
//CUSTOMIZE HERE
return factory;
}
}
Feign
By default Spring Cloud Sleuth provides integration with feign via the TraceFeignClientAutoConfiguration
. You can disable it entirely
by setting spring.sleuth.feign.enabled
to false. If you do so then no Feign related instrumentation will take place.
Part of Feign instrumentation is done via a FeignBeanPostProcessor
. You can disable it by providing the spring.sleuth.feign.processor.enabled
equal to false
.
If you set it like this then Spring Cloud Sleuth will not instrument any of your custom Feign components. All the default instrumentation
however will be still there.
Asynchronous communication
@Async annotated methods
In Spring Cloud Sleuth we’re instrumenting async related components so that the tracing information is passed between threads.
You can disable this behaviour by setting the value of spring.sleuth.async.enabled
to false
.
If you annotate your method with @Async
then we’ll automatically create a new Span with the following characteristics:
-
the Span name will be the annotated method name
-
the Span will be tagged with that method’s class name and the method name too
@Scheduled annotated methods
In Spring Cloud Sleuth we’re instrumenting scheduled method execution so that the tracing information is passed between threads. You can disable this behaviour
by setting the value of spring.sleuth.scheduled.enabled
to false
.
If you annotate your method with @Scheduled
then we’ll automatically create a new Span with the following characteristics:
-
the Span name will be the annotated method name
-
the Span will be tagged with that method’s class name and the method name too
If you want to skip Span creation for some @Scheduled
annotated classes you can set the
spring.sleuth.scheduled.skipPattern
with a regular expression that will match the fully qualified name of the
@Scheduled
annotated class.
Tip
|
If you are using spring-cloud-sleuth-stream and spring-cloud-netflix-hystrix-stream together, Span will be created for each Hystrix metrics and sent to Zipkin. This may be annoying. You can prevent this by setting spring.sleuth.scheduled.skipPattern=org.springframework.cloud.netflix.hystrix.stream.HystrixStreamTask
|
Executor, ExecutorService and ScheduledExecutorService
We’re providing LazyTraceExecutor
, TraceableExecutorService
and TraceableScheduledExecutorService
. Those implementations
are creating Spans each time a new task is submitted, invoked or scheduled.
Here you can see an example of how to pass tracing information with TraceableExecutorService
when working with CompletableFuture
:
CompletableFuture<Long> completableFuture = CompletableFuture.supplyAsync(() -> {
// perform some logic
return 1_000_000L;
}, new TraceableExecutorService(executorService,
// 'calculateTax' explicitly names the span - this param is optional
tracer, traceKeys, spanNamer, "calculateTax"));
Customization of Executors
Sometimes you need to set up a custom instance of the AsyncExecutor
. In the following snippet you
can see an example of how to set up such a custom Executor
.
@Configuration
@EnableAutoConfiguration
@EnableAsync
static class CustomExecutorConfig extends AsyncConfigurerSupport {
@Autowired BeanFactory beanFactory;
@Override public Executor getAsyncExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
// CUSTOMIZE HERE
executor.setCorePoolSize(7);
executor.setMaxPoolSize(42);
executor.setQueueCapacity(11);
executor.setThreadNamePrefix("MyExecutor-");
// DON'T FORGET TO INITIALIZE
executor.initialize();
return new LazyTraceExecutor(this.beanFactory, executor);
}
}
Messaging
Spring Cloud Sleuth integrates with Spring Integration. It creates spans for publish and
subscribe events. To disable Spring Integration instrumentation, set spring.sleuth.integration.enabled
to false.
Spring Cloud Sleuth up till version 1.0.4 is sending invalid tracing headers when using messaging. Those headers are actually
the same as the ones sent in HTTP (they contain a -
) in its name. For the sake of
backwards compatibility in 1.0.4 we’ve started sending both valid and invalid headers. Please upgrade to 1.0.4 because
in Spring Cloud Sleuth 1.2 we will remove the support for the deprecated headers.
Since 1.0.4 you can provide the spring.sleuth.integration.patterns
pattern to explicitly
provide the names of channels that you want to include for tracing. By default all channels
are included.
Zuul
We’re registering Zuul filters to propagate the tracing information (the request header is enriched with tracing data).
To disable Zuul support set the spring.sleuth.zuul.enabled
property to false
.
Running examples
You can find the running examples deployed in the Pivotal Web Services. Check them out in the following links:
Spring Cloud Consul
Camden.SR7
This project provides Consul integrations for Spring Boot apps through autoconfiguration and binding to the Spring Environment and other Spring programming model idioms. With a few simple annotations you can quickly enable and configure the common patterns inside your application and build large distributed systems with Consul based components. The patterns provided include Service Discovery, Control Bus and Configuration. Intelligent Routing (Zuul) and Client Side Load Balancing (Ribbon), Circuit Breaker (Hystrix) are provided by integration with Spring Cloud Netflix.
Install Consul
Please see the installation documentation for instructions on how to install Consul.
Consul Agent
A Consul Agent client must be available to all Spring Cloud Consul applications. By default, the Agent client is expected to be at localhost:8500
. See the Agent documentation for specifics on how to start an Agent client and how to connect to a cluster of Consul Agent Servers. For development, after you have installed consul, you may start a Consul Agent using the following command:
./src/main/bash/local_run_consul.sh
This will start an agent in server mode on port 8500, with the ui available at http://localhost:8500
Service Discovery with Consul
Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Consul provides Service Discovery services via an HTTP API and DNS. Spring Cloud Consul leverages the HTTP API for service registration and discovery. This does not prevent non-Spring Cloud applications from leveraging the DNS interface. Consul Agents servers are run in a cluster that communicates via a gossip protocol and uses the Raft consensus protocol.
How to activate
To activate Consul Service Discovery use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-consul-discovery
. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.
Registering with Consul
When a client registers with Consul, it provides meta-data about itself such as host and port, id, name and tags. An HTTP Check is created by default that Consul hits the /health
endpoint every 10 seconds. If the health check fails, the service instance is marked as critical.
Example Consul client:
@SpringBootApplication
@EnableDiscoveryClient
@RestController
public class Application {
@RequestMapping("/")
public String home() {
return "Hello world";
}
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}
(i.e. utterly normal Spring Boot app). If the Consul client is located somewhere other than localhost:8500
, the configuration is required to locate the client. Example:
spring: cloud: consul: host: localhost port: 8500
Caution
|
If you use Spring Cloud Consul Config, the above values will need to be placed in bootstrap.yml instead of application.yml .
|
The default service name, instance id and port, taken from the Environment
, are ${spring.application.name}
, the Spring Context ID and ${server.port}
respectively.
@EnableDiscoveryClient
make the app into both a Consul "service" (i.e. it registers itself) and a "client" (i.e. it can query Consul to locate other services).
HTTP Health Check
The health check for a Consul instance defaults to "/health", which is the default locations of a useful endpoint in a Spring Boot Actuator application. You need to change these, even for an Actuator application if you use a non-default context path or servlet path (e.g. server.servletPath=/foo
) or management endpoint path (e.g. management.contextPath=/admin
). The interval that Consul uses to check the health endpoint may also be configured. "10s" and "1m" represent 10 seconds and 1 minute respectively. Example:
spring: cloud: consul: discovery: healthCheckPath: ${management.contextPath}/health healthCheckInterval: 15s
Metadata and Consul tags
Consul does not yet support metadata on services. Spring Cloud’s ServiceInstance
has a Map<String, String> metadata
field. Spring Cloud Consul uses Consul tags to approximate metadata until Consul officially supports metadata. Tags with the form key=value
will be split and used as a Map
key and value respectively. Tags without the equal =
sign, will be used as both the key and value.
spring: cloud: consul: discovery: tags: foo=bar, baz
The above configuration will result in a map with foo→bar
and baz→baz
.
Making the Consul Instance ID Unique
By default a consul instance is registered with an ID that is equal to its Spring Application Context ID. By default, the Spring Application Context ID is ${spring.application.name}:comma,separated,profiles:${server.port}
. For most cases, this will allow multiple instances of one service to run on one machine. If further uniqueness is required, Using Spring Cloud you can override this by providing a unique identifier in spring.cloud.consul.discovery.instanceId
. For example:
spring: cloud: consul: discovery: instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}
With this metadata, and multiple service instances deployed on localhost, the random value will kick in there to make the instance unique. In Cloudfoundry the vcap.application.instance_id
will be populated automatically in a Spring Boot application, so the random value will not be needed.
Using the DiscoveryClient
Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate
using the logical service names instead of physical URLs.
You can also use the org.springframework.cloud.client.discovery.DiscoveryClient
which provides a simple API for discovery clients that is not specific to Netflix, e.g.
@Autowired private DiscoveryClient discoveryClient; public String serviceUrl() { List<ServiceInstance> list = discoveryClient.getInstances("STORES"); if (list != null && list.size() > 0 ) { return list.get(0).getUri(); } return null; }
Distributed Configuration with Consul
Consul provides a Key/Value Store for storing configuration and other metadata. Spring Cloud Consul Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config
folder by default. Multiple PropertySource
instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:
config/testApp,dev/ config/testApp/ config/application,dev/ config/application/
The most specific property source is at the top, with the least specific at the bottom. Properties is the config/application
folder are applicable to all applications using consul for configuration. Properties in the config/testApp
folder are only available to the instances of the service named "testApp".
Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh
will cause the configuration to be reloaded. Watching the key value store (which Consul supports) is not currently possible, but will be a future addition to this project.
How to activate
To get started with Consul Configuration use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-consul-config
. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.
This will enable auto-configuration that will setup Spring Cloud Consul Config.
Customizing
Consul Config may be customized using the following properties:
spring: cloud: consul: config: enabled: true prefix: configuration defaultContext: apps profileSeparator: '::'
-
enabled
setting this value to "false" disables Consul Config -
prefix
sets the base folder for configuration values -
defaultContext
sets the folder name used by all applications -
profileSeparator
sets the value of the separator used to separate the profile name in property sources with profiles
Config Watch
The Consul Config Watch takes advantage of the ability of consul to watch a key prefix. The Config Watch makes a blocking Consul HTTP API call to determine if any relevant configuration data has changed for the current application. If there is new configuration data a Refresh Event is published. This is equivalent to calling the /refresh
actuator endpoint.
To change the frequency of when the Config Watch is called change spring.cloud.consul.config.watch.delay
. The default value is 1000, which is in milliseconds.
To disable the Config Watch set spring.cloud.consul.config.watch.enabled=false
.
YAML or Properties with Config
It may be more convenient to store a blob of properties in YAML or Properties format as opposed to individual key/value pairs. Set the spring.cloud.consul.config.format
property to YAML
or PROPERTIES
. For example to use YAML:
spring: cloud: consul: config: format: YAML
YAML must be set in the appropriate data
key in consul. Using the defaults above the keys would look like:
config/testApp,dev/data config/testApp/data config/application,dev/data config/application/data
You could store a YAML document in any of the keys listed above.
You can change the data key using spring.cloud.consul.config.data-key
.
git2consul with Config
git2consul is a Consul community project that loads files from a git repository to individual keys into Consul. By default the names of the keys are names of the files. YAML and Properties files are supported with file extensions of .yml
and .properties
respectively. Set the spring.cloud.consul.config.format
property to FILES
. For example:
spring: cloud: consul: config: format: FILES
Given the following keys in /config
, the development
profile and an application name of foo
:
.gitignore application.yml bar.properties foo-development.properties foo-production.yml foo.properties master.ref
the following property sources would be created:
config/foo-development.properties config/foo.properties config/application.yml
The value of each key needs to be a properly formatted YAML or Properties file.
Fail Fast
It may be convenient in certain circumstances (like local development or certain test scenarios) to not fail if consul isn’t available for configuration. Setting spring.cloud.consul.config.failFast=false
in bootstrap.yml
will cause the configuration module to log a warning rather than throw an exception. This will allow the application to continue startup normally.
Consul Retry
If you expect that the consul agent may occasionally be unavailable when
your app starts, you can ask it to keep trying after a failure. You need to add
spring-retry
and spring-boot-starter-aop
to your classpath. The default
behaviour is to retry 6 times with an initial backoff interval of 1000ms and an
exponential multiplier of 1.1 for subsequent backoffs. You can configure these
properties (and others) using spring.cloud.consul.retry.*
configuration properties.
This works with both Spring Cloud Consul Config and Discovery registration.
Tip
|
To take full control of the retry add a @Bean of type
RetryOperationsInterceptor with id "consulRetryInterceptor". Spring
Retry has a RetryInterceptorBuilder that makes it easy to create one.
|
Spring Cloud Bus with Consul
How to activate
To get started with the Consul Bus use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-consul-bus
. See the Spring Cloud Project page for details on setting up your build system with the current Spring Cloud Release Train.
See the Spring Cloud Bus documentation for the available actuator endpoints and howto send custom messages.
Circuit Breaker with Hystrix
Applications can use the Hystrix Circuit Breaker provided by the Spring Cloud Netflix project by including this starter in the projects pom.xml: spring-cloud-starter-hystrix
. Hystrix doesn’t depend on the Netflix Discovery Client. The @EnableHystrix
annotation should be placed on a configuration class (usually the main class). Then methods can be annotated with @HystrixCommand
to be protected by a circuit breaker. See the documentation for more details.
Hystrix metrics aggregation with Turbine and Consul
Turbine (provided by the Spring Cloud Netflix project), aggregates multiple instances Hystrix metrics streams, so the dashboard can display an aggregate view. Turbine uses the DiscoveryClient
interface to lookup relevant instances. To use Turbine with Spring Cloud Consul, configure the Turbine application in a manner similar to the following examples:
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-netflix-turbine</artifactId> </dependency> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-consul-discovery</artifactId> </dependency>
Notice that the Turbine dependency is not a starter. The turbine starter includes support for Netflix Eureka.
spring.application.name: turbine applications: consulhystrixclient turbine: aggregator: clusterConfig: ${applications} appConfig: ${applications}
The clusterConfig
and appConfig
sections must match, so it’s useful to put the comma-separated list of service ID’s into a separate configuration property.
@EnableTurbine @EnableDiscoveryClient @SpringBootApplication public class Turbine { public static void main(String[] args) { SpringApplication.run(DemoturbinecommonsApplication.class, args); } }
Spring Cloud Zookeeper
Install Zookeeper
Please see the installation documentation for instructions on how to install Zookeeper.
Service Discovery with Zookeeper
Service Discovery is one of the key tenets of a microservice based architecture. Trying to hand configure each client or some form of convention can be very difficult to do and can be very brittle. Curator(A java library for Zookeeper) provides Service Discovery services via Service Discovery Extension. Spring Cloud Zookeeper leverages this extension for service registration and discovery.
How to activate
Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-discovery
will enable auto-configuration that will setup Spring Cloud Zookeeper Discovery.
Registering with Zookeeper
When a client registers with Zookeeper, it provides meta-data about itself such as host and port, id and name.
Example Zookeeper client:
@SpringBootApplication
@EnableDiscoveryClient
@RestController
public class Application {
@RequestMapping("/")
public String home() {
return "Hello world";
}
public static void main(String[] args) {
new SpringApplicationBuilder(Application.class).web(true).run(args);
}
}
(i.e. utterly normal Spring Boot app). If Zookeeper is located somewhere other than localhost:2181
, the configuration is required to locate the server. Example:
spring: cloud: zookeeper: connect-string: localhost:2181
Caution
|
If you use Spring Cloud Zookeeper Config, the above values will need to be placed in bootstrap.yml instead of application.yml .
|
The default service name, instance id and port, taken from the Environment
, are ${spring.application.name}
, the Spring Context ID and ${server.port}
respectively.
@EnableDiscoveryClient
makes the app into both a Zookeeper "service" (i.e. it registers itself) and a "client" (i.e. it can query Zookeeper to locate other services).
Using the DiscoveryClient
Spring Cloud has support for Feign (a REST client builder) and also Spring RestTemplate
using the logical service names instead of physical URLs.
You can also use the org.springframework.cloud.client.discovery.DiscoveryClient
which provides a simple API for discovery clients that is not specific to Netflix, e.g.
@Autowired private DiscoveryClient discoveryClient; public String serviceUrl() { List<ServiceInstance> list = discoveryClient.getInstances("STORES"); if (list != null && list.size() > 0 ) { return list.get(0).getUri().toString(); } return null; }
Zookeeper Dependencies
Using the Zookeeper Dependencies
Spring Cloud Zookeeper gives you a possibility to provide dependencies of your application as properties. As dependencies you can understand other applications that are registered
in Zookeeper and which you would like to call via Feign (a REST client builder)
and also Spring RestTemplate
.
You can also benefit from the Zookeeper Dependency Watchers functionality that lets you control and monitor what is the state of your dependencies and decide what to do with that.
How to activate Zookeeper Dependencies
-
Including a dependency on
org.springframework.cloud:spring-cloud-starter-zookeeper-discovery
will enable auto-configuration that will setup Spring Cloud Zookeeper Dependencies. -
If you have to have the
spring.cloud.zookeeper.dependencies
section properly set up - check the subsequent section for more details then the feature is active -
You can have the dependencies turned off even if you’ve provided the dependencies in your properties. Just set the property
spring.cloud.zookeeper.dependency.enabled
to false (defaults totrue
).
Setting up Zookeeper Dependencies
Let’s take a closer look at an example of dependencies representation:
spring.application.name: yourServiceName spring.cloud.zookeeper: dependencies: newsletter: path: /path/where/newsletter/has/registered/in/zookeeper loadBalancerType: ROUND_ROBIN contentTypeTemplate: application/vnd.newsletter.$version+json version: v1 headers: header1: - value1 header2: - value2 required: false stubs: org.springframework:foo:stubs mailing: path: /path/where/mailing/has/registered/in/zookeeper loadBalancerType: ROUND_ROBIN contentTypeTemplate: application/vnd.mailing.$version+json version: v1 required: true
Let’s now go through each part of the dependency one by one. The root property name is spring.cloud.zookeeper.dependencies
.
Aliases
Below the root property you have to represent each dependency has by an alias due to the constraints of Ribbon (the application id has to be placed in the URL
thus you can’t pass any complex path like /foo/bar/name). The alias will be the name that you will use instead of serviceId for DiscoveryClient
, Feign
or RestTemplate
.
In the aforementioned examples the aliases are newsletter
and mailing
. Example of Feign usage with newsletter
would be:
@FeignClient("newsletter") public interface NewsletterService { @RequestMapping(method = RequestMethod.GET, value = "/newsletter") String getNewsletters(); }
Path
Represented by path
yaml property.
Path is the path under which the dependency is registered under Zookeeper. Like presented before Ribbon operates on URLs thus this path is not compliant with its requirement. That is why Spring Cloud Zookeeper maps the alias to the proper path.
Load balancer type
Represented by loadBalancerType
yaml property.
If you know what kind of load balancing strategy has to be applied when calling this particular dependency then you can provide it in the yaml file and it will be automatically applied. You can choose one of the following load balancing strategies
-
STICKY - once chosen the instance will always be called
-
RANDOM - picks an instance randomly
-
ROUND_ROBIN - iterates over instances over and over again
Content-Type template and version
Represented by contentTypeTemplate
and version
yaml property.
If you version your api via the Content-Type
header then you don’t want to add this header to each of your requests. Also if you want to call a new version of the API you don’t want to
roam around your code to bump up the API version. That’s why you can provide a contentTypeTemplate
with a special $version
placeholder. That placeholder will be filled by the value of the
version
yaml property. Let’s take a look at an example.
Having the following contentTypeTemplate
:
application/vnd.newsletter.$version+json
and the following version
:
v1
Will result in setting up of a Content-Type
header for each request:
application/vnd.newsletter.v1+json
Default headers
Represented by headers
map in yaml
Sometimes each call to a dependency requires setting up of some default headers. In order not to do that in code you can set them up in the yaml file.
Having the following headers
section:
headers: Accept: - text/html - application/xhtml+xml Cache-Control: - no-cache
Results in adding the Accept
and Cache-Control
headers with appropriate list of values in your HTTP request.
Obligatory dependencies
Represented by required
property in yaml
If one of your dependencies is required to be up and running when your application is booting then it’s enough to set up the required: true
property in the yaml file.
If your application can’t localize the required dependency during boot time it will throw an exception and the Spring Context will fail to set up. In other words your application won’t be able to start if the required dependency is not registered in Zookeeper.
You can read more about Spring Cloud Zookeeper Presence Checker in the following sections.
Stubs
You can provide a colon separated path to the JAR containing stubs of the dependency. Example
stubs: org.springframework:foo:stubs
means that for a particular dependencies can be found under:
-
groupId:
org.springframework
-
artifactId:
foo
-
classifier:
stubs
- this is the default value
This is actually equal to
stubs: org.springframework:foo
since stubs
is the default classifier.
Configuring Spring Cloud Zookeeper Dependencies
There is a bunch of properties that you can set to enable / disable parts of Zookeeper Dependencies functionalities.
-
spring.cloud.zookeeper.dependencies
- if you don’t set this property you won’t benefit from Zookeeper Dependencies -
spring.cloud.zookeeper.dependency.ribbon.enabled
(enabled by default) - Ribbon requires explicit global configuration or a particular one for a dependency. By turning on this property runtime load balancing strategy resolution is possible and you can profit from theloadBalancerType
section of the Zookeeper Dependencies. The configuration that needs this property has an implementation ofLoadBalancerClient
that delegates to theILoadBalancer
presented in the next bullet -
spring.cloud.zookeeper.dependency.ribbon.loadbalancer
(enabled by default) - thanks to this property the customILoadBalancer
knows that the part of the URI passed to Ribbon might actually be the alias that has to be resolved to a proper path in Zookeeper. Without this property you won’t be able to register applications under nested paths. -
spring.cloud.zookeeper.dependency.headers.enabled
(enabled by default) - this property registers such aRibbonClient
that automatically will append appropriate headers and content types with version as presented in the Dependency configuration. Without this setting of those two parameters will not be operational. -
spring.cloud.zookeeper.dependency.resttemplate.enabled
(enabled by default) - when enabled will modify the request headers of@LoadBalanced
annotatedRestTemplate
so that it passes headers and content type with version set in Dependency configuration. Wihtout this setting of those two parameters will not be operational.
Spring Cloud Zookeeper Dependency Watcher
The Dependency Watcher mechanism allows you to register listeners to your dependencies. The functionality is in fact an implementation of the Observator
pattern. When a dependency changes
its state (UP or DOWN) then some custom logic can be applied.
How to activate
Spring Cloud Zookeeper Dependencies functionality needs to be enabled to profit from Dependency Watcher mechanism.
Registering a listener
In order to register a listener you have to implement an interface org.springframework.cloud.zookeeper.discovery.watcher.DependencyWatcherListener
and register it as a bean.
The interface gives you one method:
void stateChanged(String dependencyName, DependencyState newState);
If you want to register a listener for a particular dependency then the dependencyName
would be the discriminator for your concrete implementation. newState
will provide you with information
whether your dependency has changed to CONNECTED
or DISCONNECTED
.
Presence Checker
Bound with Dependency Watcher is the functionality called Presence Checker. It allows you to provide custom behaviour upon booting of your application to react accordingly to the state of your dependencies.
The default implementation of the abstract org.springframework.cloud.zookeeper.discovery.watcher.presence.DependencyPresenceOnStartupVerifier
class is the
org.springframework.cloud.zookeeper.discovery.watcher.presence.DefaultDependencyPresenceOnStartupVerifier
which works in the following way.
-
If the dependency is marked us
required
and it’s not in Zookeeper then upon booting your application will throw an exception and shutdown -
If dependency is not
required
theorg.springframework.cloud.zookeeper.discovery.watcher.presence.LogMissingDependencyChecker
will log that application is missing atWARN
level
The functionality can be overriden since the DefaultDependencyPresenceOnStartupVerifier
is registered only when there is no bean of DependencyPresenceOnStartupVerifier
.
Distributed Configuration with Zookeeper
Zookeeper provides a hierarchical namespace that allows clients to store arbitrary data, such as configuration data. Spring Cloud Zookeeper Config is an alternative to the Config Server and Client. Configuration is loaded into the Spring Environment during the special "bootstrap" phase. Configuration is stored in the /config
namespace by default. Multiple PropertySource
instances are created based on the application’s name and the active profiles that mimicks the Spring Cloud Config order of resolving properties. For example, an application with the name "testApp" and with the "dev" profile will have the following property sources created:
config/testApp,dev config/testApp config/application,dev config/application
The most specific property source is at the top, with the least specific at the bottom. Properties is the config/application
namespace are applicable to all applications using zookeeper for configuration. Properties in the config/testApp
namespace are only available to the instances of the service named "testApp".
Configuration is currently read on startup of the application. Sending a HTTP POST to /refresh
will cause the configuration to be reloaded. Watching the configuration namespace (which Zookeeper supports) is not currently implemented, but will be a future addition to this project.
How to activate
Including a dependency on org.springframework.cloud:spring-cloud-starter-zookeeper-config
will enable auto-configuration that will setup Spring Cloud Zookeeper Config.
Customizing
Zookeeper Config may be customized using the following properties:
spring: cloud: zookeeper: config: enabled: true root: configuration defaultContext: apps profileSeparator: '::'
-
enabled
setting this value to "false" disables Zookeeper Config -
root
sets the base namespace for configuration values -
defaultContext
sets the name used by all applications -
profileSeparator
sets the value of the separator used to separate the profile name in property sources with profiles
Spring Boot Cloud CLI
Spring Boot CLI provides Spring
Boot command line features for Spring
Cloud. You can write Groovy scripts to run Spring Cloud component
applications (e.g. @EnableEurekaServer
). You can also easily do
things like encryption and decryption to support Spring Cloud Config
clients with secret configuration values. With the Launcher CLI you
can launch services like Eureka, Zipkin, Config Server
conveniently all at once from the command line (very useful at
development time).
Note
|
Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. |
Installation
To install, make sure you have Spring Boot CLI (1.4.1 or better):
$ spring version Spring CLI v1.4.1.RELEASE
E.g. for SDKMan users
$ sdk install springboot 1.4.1.RELEASE
$ sdk use springboot 1.4.1.RELEASE
and install the Spring Cloud plugin
$ mvn install
$ spring install org.springframework.cloud:spring-cloud-cli:1.2.3.BUILD-SNAPSHOT
Important
|
Prerequisites: to use the encryption and decryption features you need the full-strength JCE installed in your JVM (it’s not there by default). You can download the "Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files" from Oracle, and follow instructions for installation (essentially replace the 2 policy files in the JRE lib/security directory with the ones that you downloaded). |
Running Spring Cloud Services in Development
The Launcher CLI can be used to run common services like Eureka,
Config Server etc. from the command line. To list the available
services you can do spring cloud --list
, and to launch a default set
of services just spring cloud
. To choose the services to deploy,
just list them on the command line, e.g.
$ spring cloud eureka configserver h2 kafka zipkin
Summary of supported deployables:
Service | Name | Address | Description |
---|---|---|---|
eureka |
Eureka Server |
Eureka server for service registration and discovery. All the other services show up in its catalog by default. |
|
configserver |
Config Server |
Spring Cloud Config Server running in the "native" profile and serving configuration from the local directory ./launcher |
|
h2 |
H2 Database |
http://localhost:9095 (console), jdbc:h2:tcp://localhost:9096/{data} |
Relation database service. Use a file path for |
kafka |
Kafka Broker |
http://localhost:9091 (actuator endpoints), localhost:9092 |
|
hystrixdashboard |
Hystrix Dashboard |
Any Spring Cloud app that declares Hystrix circuit breakers publishes metrics on |
|
dataflow |
Dataflow Server |
Spring Cloud Dataflow server with UI at /admin-ui. Connect the Dataflow shell to target at root path. |
|
zipkin |
Zipkin Server |
Zipkin Server with UI for visualizing traces. Stores span data in memory and accepts them via HTTP POST of JSON data. |
Each of these apps can be configured using a local YAML file with the same name (in the current
working directory or a subdirectory called "config" or in ~/.spring-cloud
). E.g. in configserver.yml
you might want to
do something like this to locate a local git repository for the backend:
spring:
profiles:
active: git
cloud:
config:
server:
git:
uri: file://${user.home}/dev/demo/config-repo
Adding Additional Applications
Additional applications can be added to ./config/cloud.yml
(not
./config.yml
because that would replace the defaults), e.g. with
spring:
cloud:
launcher:
deployables:
source:
coordinates: maven://com.example:source:0.0.1-SNAPSHOT
port: 7000
sink:
coordinates: maven://com.example:sink:0.0.1-SNAPSHOT
port: 7001
when you list the apps:
$ spring cloud --list
source sink configserver dataflow eureka h2 hystrixdashboard kafka zipkin
(notice the additional apps at the start of the list).
Writing Groovy Scripts and Running Applications
Spring Cloud CLI has support for most of the Spring Cloud declarative
features, such as the @Enable*
class of annotations. For example,
here is a fully functional Eureka server
@EnableEurekaServer
class Eureka {}
which you can run from the command line like this
$ spring run app.groovy
To include additional dependencies, often it suffices just to add the
appropriate feature-enabling annotation, e.g. @EnableConfigServer
,
@EnableOAuth2Sso
or @EnableEurekaClient
. To manually include a
dependency you can use a @Grab
with the special "Spring Boot" short
style artifact co-ordinates, i.e. with just the artifact ID (no need
for group or version information), e.g. to set up a client app to
listen on AMQP for management events from the Spring CLoud Bus:
@Grab('spring-cloud-starter-bus-amqp')
@RestController
class Service {
@RequestMapping('/')
def home() { [message: 'Hello'] }
}
Encryption and Decryption
The Spring Cloud CLI comes with an "encrypt" and a "decrypt" command. Both accept arguments in the same form with a key specified as a mandatory "--key", e.g.
$ spring encrypt mysecret --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda $ spring decrypt --key foo 682bc583f4641835fa2db009355293665d2647dade3375c0ee201de2a49f7bda mysecret
To use a key in a file (e.g. an RSA public key for encyption) prepend the key value with "@" and provide the file path, e.g.
$ spring encrypt mysecret --key @${HOME}/.ssh/id_rsa.pub AQAjPgt3eFZQXwt8tsHAVv/QHiY5sI2dRcR+...
Spring Cloud Security
Spring Cloud Security offers a set of primitives for building secure applications and services with minimum fuss. A declarative model which can be heavily configured externally (or centrally) lends itself to the implementation of large systems of co-operating, remote components, usually with a central indentity management service. It is also extremely easy to use in a service platform like Cloud Foundry. Building on Spring Boot and Spring Security OAuth2 we can quickly create systems that implement common patterns like single sign on, token relay and token exchange.
Note
|
Spring Cloud is released under the non-restrictive Apache 2.0 license. If you would like to contribute to this section of the documentation or if you find an error, please find the source code and issue trackers in the project at github. |
Quickstart
OAuth2 Single Sign On
Here’s a Spring Cloud "Hello World" app with HTTP Basic authentication and a single user account:
@Grab('spring-boot-starter-security')
@Controller
class Application {
@RequestMapping('/')
String home() {
'Hello World'
}
}
You can run it with spring run app.groovy
and watch the logs for the password (username is "user"). So far this is just the default for a Spring Boot app.
Here’s a Spring Cloud app with OAuth2 SSO:
@Controller
@EnableOAuth2Sso
class Application {
@RequestMapping('/')
String home() {
'Hello World'
}
}
Spot the difference? This app will actually behave exactly the same as the previous one, because it doesn’t know it’s OAuth2 credentals yet.
You can register an app in github quite easily, so try that if you want a production app on your own domain. If you are happy to test on localhost:8080, then set up these properties in your application configuration:
spring:
oauth2:
client:
clientId: bd1c0a783ccdd1c9b9e4
clientSecret: 1a9030fbca47a5b2c28e92f19050bb77824b5ad1
accessTokenUri: https://github.com/login/oauth/access_token
userAuthorizationUri: https://github.com/login/oauth/authorize
clientAuthenticationScheme: form
resource:
userInfoUri: https://api.github.com/user
preferTokenInfo: false
run the app above and it will redirect to github for authorization. If you are already signed into github you won’t even notice that it has authenticated. These credentials will only work if your app is running on port 8080.
To limit the scope that the client asks for when it obtains an access token
you can set spring.oauth2.client.scope
(comma separated or an array in YAML). By
default the scope is empty and it is up to to Authorization Server to
decide what the defaults should be, usually depending on the settings in
the client registration that it holds.
Note
|
The examples above are all Groovy scripts. If you want to write the same code in Java (or Groovy) you need to add Spring Security OAuth2 to the classpath (e.g. see the sample here). |
OAuth2 Protected Resource
You want to protect an API resource with an OAuth2 token? Here’s a simple example (paired with the client above):
@Grab('spring-cloud-starter-security')
@RestController
@EnableResourceServer
class Application {
@RequestMapping('/')
def home() {
[message: 'Hello World']
}
}
and
spring:
oauth2:
resource:
userInfoUri: https://api.github.com/user
preferTokenInfo: false
More Detail
Single Sign On
Note
|
All of the OAuth2 SSO and resource server features moved to Spring Boot in version 1.3. You can find documentation in the Spring Boot user guide. |
Token Relay
A Token Relay is where an OAuth2 consumer acts as a Client and forwards the incoming token to outgoing resource requests. The consumer can be a pure Client (like an SSO application) or a Resource Server.
Client Token Relay
If your app is a user facing OAuth2 client (i.e. has declared
@EnableOAuth2Sso
or @EnableOAuth2Client
) then it has an
OAuth2ClientContext
in request scope from Spring Boot. You can
create your own OAuth2RestTemplate
from this context and an
autowired OAuth2ProtectedResourceDetails
, and then the context will
always forward the access token downstream, also refreshing the access
token automatically if it expires. (These are features of Spring
Security and Spring Boot.)
Note
|
Spring Boot (1.4.1) does not create an
OAuth2ProtectedResourceDetails automatically if you are using
client_credentials tokens. In that case you need to create your own
ClientCredentialsResourceDetails and configure it with
@ConfigurationProperties("security.oauth2.client") .
|
Client Token Relay in Zuul Proxy
If your app also has a
Spring
Cloud Zuul embedded reverse proxy (using @EnableZuulProxy
) then you
can ask it to forward OAuth2 access tokens downstream to the services
it is proxying. Thus the SSO app above can be enhanced simply like
this:
@Controller
@EnableOAuth2Sso
@EnableZuulProxy
class Application {
}
and it will (in addition to logging the user in and grabbing a token)
pass the authentication token downstream to the /proxy/*
services. If those services are implemented with
@EnableResourceServer
then they will get a valid token in the
correct header.
How does it work? The @EnableOAuth2Sso
annotation pulls in
spring-cloud-starter-security
(which you could do manually in a
traditional app), and that in turn triggers some autoconfiguration for
a ZuulFilter
, which itself is activated because Zuul is on the
classpath (via @EnableZuulProxy
). The
filter
just extracts an access token from the currently authenticated user,
and puts it in a request header for the downstream requests.
Resource Server Token Relay
If your app has @EnableResourceServer
you might want to relay the
incoming token downstream to other services. If you use a
RestTemplate
to contact the downstream services then this is just a
matter of how to create the template with the right context.
If your service uses UserInfoTokenServices
to authenticate incoming
tokens (i.e. it is using the security.oauth2.user-info-uri
configuration), then you can simply create an OAuth2RestTemplate
using an autowired OAuth2ClientContext
(it will be populated by the
authentication process before it hits the backend code). Equivalently
(with Spring Boot 1.4), you could inject a
UserInfoRestTemplateFactory
and grab its OAuth2RestTemplate
in
your configuration. For example:
@Bean
public OAuth2RestTemplate restTemplate(UserInfoRestTemplateFactory factory) {
return factory.getUserInfoRestTemplate();
}
This rest template will then have the same OAuth2ClientContext
(request-scoped) that is used by the authentication filter, so you can
use it to send requests with the same access token.
If your app is not using UserInfoTokenServices
but is still a client
(i.e. it declares @EnableOAuth2Client
or @EnableOAuth2Sso
), then
with Spring Security Cloud any OAuth2RestOperations
that the user
creates from an @Autowired
@OAuth2Context
will also forward
tokens. This feature is implemented by default as an MVC handler
interceptor, so it only works in Spring MVC. If you are not using MVC
you could use a custom filter or AOP interceptor wrapping an
AccessTokenContextRelay
to provide the same feature.
Here’s a basic example showing the use of an autowired rest template created elsewhere ("foo.com" is a Resource Server accepting the same tokens as the surrounding app):
@Autowired
private OAuth2RestOperations restTemplate;
@RequestMapping("/relay")
public String relay() {
ResponseEntity<String> response =
restTemplate.getForEntity("https://foo.com/bar", String.class);
return "Success! (" + response.getBody() + ")";
}
If you don’t want to forward tokens (and that is a valid
choice, since you might want to act as yourself, rather than the
client that sent you the token), then you only need to create your own
OAuth2Context
instead of autowiring the default one.
Feign clients will also pick up an interceptor that uses the
OAuth2ClientContext
if it is available, so they should also do a
token relay anywhere where a RestTemplate
would.
Configuring Authentication Downstream of a Zuul Proxy
You can control the authorization behaviour downstream of an
@EnableZuulProxy
through the proxy.auth.*
settings. Example:
proxy:
auth:
routes:
customers: oauth2
stores: passthru
recommendations: none
In this example the "customers" service gets an OAuth2 token relay, the "stores" service gets a passthrough (the authorization header is just passed downstream), and the "recommendations" service has its authorization header removed. The default behaviour is to do a token relay if there is a token available, and passthru otherwise.
See ProxyAuthenticationProperties for full details.
Spring Cloud for Cloud Foundry
Spring Cloud for Cloudfoundry makes it easy to run Spring Cloud apps in Cloud Foundry (the Platform as a Service). Cloud Foundry has the notion of a "service", which is middlware that you "bind" to an app, essentially providing it with an environment variable containing credentials (e.g. the location and username to use for the service).
The spring-cloud-cloudfoundry-web
project provides basic support for
some enhanced features of webapps in Cloud Foundry: binding
automatically to single-sign-on services and optionally enabling
sticky routing for discovery.
The spring-cloud-cloudfoundry-discovery
project provides an
implementation of Spring Cloud Commons DiscoveryClient
so you can
@EnableDiscoveryClient
and provide your credentials as
spring.cloud.cloudfoundry.discovery.[email,password]
and then you
can use the DiscoveryClient
directly or via a LoadBalancerClient
(also *.url
if you are not connecting to
Pivotal Web Services).
The first time you use it the discovery client might be slow owing to the fact that it has to get an access token from Cloud Foundry.
Discovery
Here’s a Spring Cloud app with Cloud Foundry discovery:
@Grab('org.springframework.cloud:spring-cloud-cloudfoundry')
@RestController
@EnableDiscoveryClient
class Application {
@Autowired
DiscoveryClient client
@RequestMapping('/')
String home() {
'Hello from ' + client.getLocalServiceInstance()
}
}
If you run it without any service bindings:
$ spring jar app.jar app.groovy $ cf push -p app.jar
It will show its app name in the home page.
The DiscoveryClient
can lists all the apps in a space, according to
the credentials it is authenticated with, where the space defaults to
the one the client is running in (if any). If neither org nor space
are configured, they default per the user’s profile in Cloud Foundry.
Single Sign On
Note
|
All of the OAuth2 SSO and resource server features moved to Spring Boot in version 1.3. You can find documentation in the Spring Boot user guide. |
This project provides automatic binding from CloudFoundry service
credentials to the Spring Boot features. If you have a CloudFoundry
service called "sso", for instance, with credentials containing
"client_id", "client_secret" and "auth_domain", it will bind
automatically to the Spring OAuth2 client that you enable with
@EnableOAuth2Sso
(from Spring Boot). The name of the service can be
parameterized using spring.oauth2.sso.serviceId
.
Unresolved directive in spring-cloud.adoc - include::/Users/ryanjbaxter/git-repos/spring-cloud/scripts/docs/../cluster/docs/src/main/asciidoc/spring-cloud-cluster.adoc[]
Spring Cloud Contract
Documentation Authors: Adam Dudczak, Mathias Düsterhöft, Marcin Grzejszczak, Dennis Kieselhorst, Jakub Kubryński, Karol Lassak, Olga Maciaszek-Sharma, Mariusz Smykuła, Dave Syer
Camden.SR7
Spring Cloud Contract
What you always need is confidence in pushing new features into a new application or service in a distributed system. This project provides support for Consumer Driven Contracts and service schemas in Spring applications, covering a range of options for writing tests, publishing them as assets, asserting that a contract is kept by producers and consumers, for HTTP and message-based interactions.
Spring Cloud Contract WireMock
Modules giving you the possibility to use WireMock with different servers by using the "ambient" server embedded in a Spring Boot application. Check out the samples for more details.
Important
|
The Spring Cloud Release Train BOM imports spring-cloud-contract-dependencies
which in turn has exclusions for the dependencies needed by WireMock. This might lead to a situation that
even if you’re not using Spring Cloud Contract then your dependencies will be influenced
anyways.
|
If you have a Spring Boot application that uses Tomcat as an embedded
server, for example (the default with spring-boot-starter-web
), then
you can simply add spring-cloud-contract-wiremock
to your classpath
and add @AutoConfigureWireMock
in order to be able to use Wiremock
in your tests. Wiremock runs as a stub server and you can register
stub behaviour using a Java API or via static JSON declarations as
part of your test. Here’s a simple example:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureWireMock(port = 0)
public class WiremockForDocsTests {
// A service that calls out over HTTP
@Autowired private Service service;
// Using the WireMock APIs in the normal way:
@Test
public void contextLoads() throws Exception {
// Stubbing WireMock
stubFor(get(urlEqualTo("/resource"))
.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World!");
}
}
To start the stub server on a different port use @AutoConfigureWireMock(port=9999)
(for example), and for a random port use the value 0. The stub server port will be bindable in the test application context as "wiremock.server.port". Using @AutoConfigureWireMock
adds a bean of type WiremockConfiguration
to your test application context, where it will be cached in between methods and classes having the same context, just like for normal Spring integration tests.
Registering Stubs Automatically
If you use @AutoConfigureWireMock
then it will register WireMock
JSON stubs from the file system or classpath, by default from
file:src/test/resources/mappings
. You can customize the locations
using the stubs
attribute in the annotation, which can be a resource
pattern (ant-style) or a directory, in which case */.json
is
appended. Example:
@RunWith(SpringRunner.class) @SpringBootTest @AutoConfigureWireMock(stubs="classpath:/stubs") public class WiremockImportApplicationTests { @Autowired private Service service; @Test public void contextLoads() throws Exception { assertThat(this.service.go()).isEqualTo("Hello World!"); } }
Note
|
Actually WireMock always loads mappings from
src/test/resources/mappings as well as the custom locations in the
stubs attribute. To change this behaviour you have to also specify a
files root as described next.
|
Using Files to Specify the Stub Bodies
WireMock can read response bodies from files on the classpath or file
system. In that case you will see in the JSON DSL that the response
has a "bodyFileName" instead of a (literal) "body". The files are
resolved relative to a root directory src/test/resources/__files
by
default. To customize this location you can set the files
attribute
in the @AutoConfigureWireMock
annotation to the location of the
parent directory (i.e. the place __files
is a
subdirectory). You can use Spring resource notation to refer to
file:…
or classpath:…
locations (but generic URLs are not
supported). A list of values can be given and WireMock will resolve
the first file that exists when it needs to find a response body.
Note
|
when you configure the files root, then it affects the
automatic loading of stubs as well (they come from the root location
in a subdirectory called "mappings"). The value of files has no
effect on the stubs loaded explicitly from the stubs attribute.
|
Alternative: Using JUnit Rules
For a more conventional WireMock experience, using JUnit @Rules
to
start and stop the server, just use the WireMockSpring
convenience
class to obtain an Options
instance:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class WiremockForDocsClassRuleTests {
// Start WireMock on some dynamic port
// for some reason `dynamicPort()` is not working properly
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(
WireMockSpring.options().dynamicPort());
// A service that calls out over HTTP to localhost:${wiremock.port}
@Autowired
private Service service;
// Using the WireMock APIs in the normal way:
@Test
public void contextLoads() throws Exception {
// Stubbing WireMock
wiremock.stubFor(get(urlEqualTo("/resource"))
.willReturn(aResponse().withHeader("Content-Type", "text/plain").withBody("Hello World!")));
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World!");
}
}
The use @ClassRule
means that the server will shut down after all the methods in this class.
Relaxed SSL Validation for Rest Template
WireMock allows you to stub a "secure" server with an "https" URL protocol. If your application wants to contact that stub server in an integration test, then it will find that the SSL certificates are not valid (it’s the usual problem with self-installed certificates). The best option is often to just re-configure the client to use "http", but if that’s not open to you then you can ask Spring to configure an HTTP client that ignores SSL validation errors (just for tests).
To make this work with minimum fuss you need to be using the Spring Boot RestTemplateBuilder
in your app,
e.g.
@Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
return builder.build();
}
This is because the builder is passed through callbacks to initalize it, so the SSL validation can be set up
in the client at that point. This will happen automatically in your test if you are using the
@AutoConfigureWireMock
annotation (or the stub runner). If you are using the JUnit @Rule
approach you need
to add the @AutoConfigureHttpClient
annotation as well:
@RunWith(SpringRunner.class)
@SpringBootTest("app.baseUrl=https://localhost:6443")
@AutoConfigureHttpClient
public class WiremockHttpsServerApplicationTests {
@ClassRule
public static WireMockClassRule wiremock = new WireMockClassRule(
WireMockSpring.options().httpsPort(6443));
...
}
If you are using spring-boot-starter-test
then you will have the Apache HTTP client on the classpath and it will
be selected by the RestTemplateBuilder
and configured to ignore SSL errors. If you are using the default java.net
client you don’t need the annotation (but it won’t do any harm). There is no support currently for other clients, but
it may be added in future releases.
WireMock and Spring MVC Mocks
Spring Cloud Contract provides a convenience class that can load JSON WireMock stubs into a
Spring MockRestServiceServer
. Here’s an example:
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = WebEnvironment.NONE)
public class WiremockForDocsMockServerApplicationTests {
@Autowired
private RestTemplate restTemplate;
@Autowired
private Service service;
@Test
public void contextLoads() throws Exception {
// will read stubs classpath
MockRestServiceServer server = WireMockRestServiceServer.with(this.restTemplate)
.baseUrl("http://example.org").stubs("classpath:/stubs/resource.json")
.build();
// We're asserting if WireMock responded properly
assertThat(this.service.go()).isEqualTo("Hello World");
server.verify();
}
}
The baseUrl
is prepended to all mock calls, and the stubs()
method takes a stub path resource pattern as an argument. So in this
example the stub defined at /stubs/resource.json
is loaded into the
mock server, so if the RestTemplate
is asked to visit
http://example.org/
it will get the responses as declared
there. More than one stub pattern can be specified, and each one can
be a directory (for a recursive list of all ".json"), or a fixed
filename (like in the example above) or an ant-style pattern. The JSON
format is the normal WireMock format which you can read about in the
WireMock website.
Currently we support Tomcat, Jetty and Undertow as Spring Boot embedded servers, and Wiremock itself has "native" support for a particular version of Jetty (currently 9.2). To use the native Jetty you need to add the native wiremock dependencies and exclude the Spring Boot container if there is one.
Generating Stubs using RestDocs
Spring RestDocs can be
used to generate documentation (e.g. in asciidoctor format) for an
HTTP API with Spring MockMvc or RestEasy. At the same time as you
generate documentation for your API, you can also generate WireMock
stubs, by using Spring Cloud Contract WireMock. Just write your normal
RestDocs test cases and use @AutoConfigureRestDocs
to have stubs
automatically in the restdocs output directory. For example:
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureRestDocs(outputDir = "target/snippets")
@AutoConfigureMockMvc
public class ApplicationTests {
@Autowired
private MockMvc mockMvc;
@Test
public void contextLoads() throws Exception {
mockMvc.perform(get("/resource"))
.andExpect(content().string("Hello World"))
.andDo(document("resource"));
}
}
From this test will be generated a WireMock stub at "target/snippets/stubs/resource.json". It matches all GET requests to the "/resource" path.
Without any additional configuration this will create a stub with a request matcher for the HTTP method and all headers except "host" and "content-length". To match the request more precisely, for example to match the body of a POST or PUT, we need to explicitly create a request matcher. This will do two things: 1) create a stub that only matches the way you specify, 2) assert that the request in the test case also matches the same conditions.
The main entry point for this is WireMockRestDocs.verify()
which can
be used as a substitute for the document()
convenience method. For
example:
@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureRestDocs(outputDir = "target/snippets")
@AutoConfigureMockMvc
public class ApplicationTests {
@Autowired
private MockMvc mockMvc;
@Test
public void contextLoads() throws Exception {
mockMvc.perform(post("/resource")
.content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
.andExpect(status().isOk())
.andDo(verify().jsonPath("$.id")
.stub("resource"));
}
}
So this contract is saying: any valid POST with an "id" field will get
back an the same response as in this test. You can chain together
calls to .jsonPath()
to add additional matchers. The
JayWay documentation can help you
to get up to speed with JSON Path if it is unfamiliar to you.
Instead of the jsonPath
and contentType
convenience methods, you
can also use the WireMock APIs to verify the request matches the
created stub. Example:
@Test
public void contextLoads() throws Exception {
mockMvc.perform(post("/resource")
.content("{\"id\":\"123456\",\"message\":\"Hello World\"}"))
.andExpect(status().isOk())
.andDo(verify()
.wiremock(WireMock.post(
urlPathEquals("/resource"))
.withRequestBody(matchingJsonPath("$.id"))
.stub("post-resource"));
}
The WireMock API is rich - you can match headers, query parameters, and request body by regex as well as by json path - so this can useful to create stubs with a wider range of parameters. The above example will generate a stub something like this:
{
"request" : {
"url" : "/resource",
"method" : "POST",
"bodyPatterns" : [ {
"matchesJsonPath" : "$.id"
}]
},
"response" : {
"status" : 200,
"body" : "Hello World",
"headers" : {
"X-Application-Context" : "application:-1",
"Content-Type" : "text/plain"
}
}
}
Note
|
You can use either the wiremock() method or the jsonPath()
and contentType() methods to create request matchers, but not both.
|
On the consumer side, you can make the resource.json
generated above
available on the classpath (by publishing stubs as JARs for example).
After that, you can create a stub using WireMock in a
number of different ways, including as described above using
@AutoConfigureWireMock(stubs="classpath:resource.json")
.
Generating Contracts using RestDocs
Another thing that can be generated with Spring RestDocs is the Spring Cloud Contract DSL file and documentation. If you combine that with Spring Cloud WireMock then you’re getting both the contracts and stubs.
Tip
|
You might wonder why this functionality is in the WireMock module. Come to think of it, it does make sense since it makes little sense to generate only contracts and not generate the stubs. That’s why we suggest to do both. |
Let’s imagine the following test:
this.mockMvc.perform(post("/foo")
.accept(MediaType.APPLICATION_PDF)
.accept(MediaType.APPLICATION_JSON)
.contentType(MediaType.APPLICATION_JSON)
.content("{\"foo\": 23 }"))
.andExpect(status().isOk())
.andExpect(content().string("bar"))
// first WireMock
.andDo(WireMockRestDocs.verify()
.jsonPath("$[?(@.foo >= 20)]")
.contentType(MediaType.valueOf("application/json"))
.stub("shouldGrantABeerIfOldEnough"))
// then Contract DSL documentation
.andDo(document("index", SpringCloudContractRestDocs.dslContract()));
This will lead in the creation of the stub as presented in the previous section, contract will get generated and a documentation file too.
The contract will be called index.groovy
and look more like this.
import org.springframework.cloud.contract.spec.Contract
Contract.make {
request {
method 'POST'
url 'http://localhost:8080/foo'
body('''
{"foo": 23 }
''')
headers {
header('''Accept''', '''application/json''')
header('''Content-Type''', '''application/json''')
header('''Host''', '''localhost:8080''')
header('''Content-Length''', '''12''')
}
}
response {
status 200
body('''
bar
''')
headers {
header('''Content-Type''', '''application/json;charset=UTF-8''')
header('''Content-Length''', '''3''')
}
testMatchers {
jsonPath('$[?(@.foo >= 20)]', byType())
}
}
}
the generated document (example for Asciidoc) will contain a formatted contract
(the location of this file would be index/dsl-contract.adoc
).
Spring Cloud Contract Verifier
Introduction
Tip
|
The Accurest project was initially started by Marcin Grzejszczak and Jakub Kubrynski (codearte.io) |
Just to make long story short - Spring Cloud Contract Verifier is a tool that enables Consumer Driven Contract (CDC) development of JVM-based applications. It is shipped with Contract Definition Language (DSL). Contract definitions are used to produce following resources:
-
JSON stub definitions to be used by WireMock when doing integration testing on the client code (client tests). Test code must still be written by hand, test data is produced by Spring Cloud Contract Verifier.
-
Messaging routes if you’re using one. We’re integrating with Spring Integration, Spring Cloud Stream, Spring AMQP and Apache Camel. You can however set your own integrations if you want to
-
Acceptance tests (in JUnit or Spock) used to verify if server-side implementation of the API is compliant with the contract (server tests). Full test is generated by Spring Cloud Contract Verifier.
Spring Cloud Contract Verifier moves TDD to the level of software architecture.
Spring Cloud Contract video
You can check out the video from the Warsaw JUG about Spring Cloud Contract:
Why?
Let us assume that we have a system comprising of multiple microservices:
Testing issues
If we wanted to test the application in top left corner if it can communicate with other services then we could do one of two things:
-
deploy all microservices and perform end to end tests
-
mock other microservices in unit / integration tests
Both have their advantages but also a lot of disadvantages. Let’s focus on the latter.
Deploy all microservices and perform end to end tests
Advantages:
-
simulates production
-
tests real communication between services
Disadvantages:
-
to test one microservice we would have to deploy 6 microservices, a couple of databases etc.
-
the environment where the tests would be conducted would be locked for a single suite of tests (i.e. nobody else would be able to run the tests in the meantime).
-
long to run
-
very late feedback
-
extremely hard to debug
Mock other microservices in unit / integration tests
Advantages:
-
very fast feedback
-
no infrastructure requirements
Disadvantages:
-
the implementor of the service creates stubs thus they might have nothing to do with the reality
-
you can go to production with passing tests and failing production
To solve the aforementioned issues Spring Cloud Contract Verifier with Stub Runner were created. Their main idea is to give you very fast feedback, without the need to set up the whole world of microservices.
If you work on stubs then the only applications you need are those that your application is using directly.
Spring Cloud Contract Verifier gives you the certainty that the stubs that you’re using were created by the service that you’re calling. Also if you can use them it means that they were tested against the producer’s side. In other words - you can trust those stubs.
Purposes
The main purposes of Spring Cloud Contract Verifier with Stub Runner are:
-
to ensure that WireMock / Messaging stubs (used when developing the client) are doing exactly what actual server-side implementation will do,
-
to promote ATDD method and Microservices architectural style,
-
to provide a way to publish changes in contracts that are immediately visible on both sides,
-
to generate boilerplate test code used on the server side.
Important
|
Spring Cloud Contract Verifier’s purpose is NOT to start writing business features in the contracts. Let’s assume that we have a business use case of fraud check. If a user can be a fraud for 100 different reasons, we would assume that you would create 2 contracts. One for the positive and one for the negative fraud case. Contract tests are used to test contracts between applications and not to simulate full behaviour. |
Client Side
During the tests you want to have a WireMock instance / Messaging route up and running that simulates the service Y. You would like to feed that instance with a proper stub definition. That stub definition would need to be valid and should also be reusable on the server side.
Summing it up: On this side, in the stub definition, you can use patterns for request stubbing and you need exact values for responses.
Server Side
Being a service Y since you are developing your stub, you need to be sure that it’s actually resembling your concrete implementation. You can’t have a situation where your stub acts in one way and your application on production behaves in a different way.
That’s why from the provided stub acceptance tests will be generated that will ensure that your application behaves in the same way as you define in your stub.
Summing it up: On this side, in the stub definition, you need exact values as request and can use patterns/methods for response verification.
Step by step guide to CDC
Let’s take an example of Fraud Detection and Loan Issuance process. The business scenario is such that we want to issue loans to people but don’t want them to steal the money from us. The current implementation of our system grants loans to everybody.
Let’s assume that the Loan Issuance
is a client to the
Fraud Detection
server. In the current sprint we are required to develop a new feature - if a client wants to borrow too much money then we mark him as fraud.
Technical remark - Fraud Detection will have artifact id http-server
, Loan Issuance http-client
and both have group id com.example
.
Social remark - both client and server development teams need to communicate directly and discuss changes while going through the process. CDC is all about communication.
Tip
|
In this case the ownership of the contracts lays on the producer side. It means that physically all the contract are present in the producer’s repository |
Technical note
If using the SNAPSHOT / Milestone / Release Candidate versions please add the following section to your
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
repositories {
mavenCentral()
mavenLocal()
maven { url "http://repo.spring.io/snapshot" }
maven { url "http://repo.spring.io/milestone" }
maven { url "http://repo.spring.io/release" }
}
Consumer side (Loan Issuance)
As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):
start doing TDD by writing a test to your feature
@Test
public void shouldBeRejectedDueToAbnormalLoanAmount() {
// given:
LoanApplication application = new LoanApplication(new Client("1234567890"),
99999);
// when:
LoanApplicationResult loanApplication = service.loanApplication(application);
// then:
assertThat(loanApplication.getLoanApplicationStatus())
.isEqualTo(LoanApplicationStatus.LOAN_APPLICATION_REJECTED);
assertThat(loanApplication.getRejectionReason()).isEqualTo("Amount too high");
}
We’ve just written a test of our new feature. If a loan application for a big amount is received we should reject that loan application with some description.
write the missing implementation
At some point in time you need to send a request to the Fraud Detection service. Let’s assume that we’d like to send the request containing the id of the client and the amount he wants to borrow from us. We’d like to send it to the /fraudcheck
url via the PUT
method.
ResponseEntity<FraudServiceResponse> response =
restTemplate.exchange("http://localhost:" + port + "/fraudcheck", HttpMethod.PUT,
new HttpEntity<>(request, httpHeaders),
FraudServiceResponse.class);
For simplicity we’ve hardcoded the port of the Fraud Detection service at 8080
and our application is running on 8090
.
If we’d start the written test it would obviously break since we have no service running on port 8080
.
clone the Fraud Detection service repository locally
We’ll start playing around with the server side contract. That’s why we need to first clone it.
git clone https://your-git-server.com/server-side.git local-http-server-repo
define the contract locally in the repo of Fraud Detection service
As consumers we need to define what exactly we want to achieve. We need to formulate our expectations. That’s why we write the following contract.
Important
|
We’re placing the contract under src/test/resources/contract/fraud folder. The fraud folder
is important cause we’ll reference that folder in the producer’s test base class name.
|
package contracts
org.springframework.cloud.contract.spec.Contract.make {
request { // (1)
method 'PUT' // (2)
url '/fraudcheck' // (3)
body([ // (4)
"client.id": $(regex('[0-9]{10}')),
loanAmount: 99999
])
headers { // (5)
contentType('application/vnd.fraud.v1+json')
}
}
response { // (6)
status 200 // (7)
body([ // (8)
fraudCheckStatus: "FRAUD",
"rejection.reason": "Amount too high"
])
headers { // (9)
contentType('application/vnd.fraud.v1+json')
}
}
}
/*
Since we don't want to force on the user to hardcode values of fields that are dynamic
(timestamps, database ids etc.), one can parametrize those entries. If you wrap your field's
value in a `$(...)` or `value(...)` and provide a dynamic value of a field then
the concrete value will be generated for you. If you want to be really explicit about
which side gets which value you can do that by using the `value(consumer(...), producer(...))` notation.
That way what's present in the `consumer` section will end up in the produced stub. What's
there in the `producer` will end up in the autogenerated test. If you provide only the
regular expression side without the concrete value then Spring Cloud Contract will generate one for you.
From the Consumer perspective, when shooting a request in the integration test:
(1) - If the consumer sends a request
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/vnd.fraud.v1+json`
(6) - then the response will be sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` equal to `application/vnd.fraud.v1+json`
From the Producer perspective, in the autogenerated producer-side test:
(1) - A request will be sent to the producer
(2) - With the "PUT" method
(3) - to the URL "/fraudcheck"
(4) - with the JSON body that
* has a field `clientId` that will have a generated value that matches a regular expression `[0-9]{10}`
* has a field `loanAmount` that is equal to `99999`
(5) - with header `Content-Type` equal to `application/vnd.fraud.v1+json`
(6) - then the test will assert if the response has been sent with
(7) - status equal `200`
(8) - and JSON body equal to
{ "fraudCheckStatus": "FRAUD", "rejectionReason": "Amount too high" }
(9) - with header `Content-Type` matching `application/vnd.fraud.v1+json.*`
*/
The Contract is written using a statically typed Groovy DSL. You might be wondering what are those
value(client(…), server(…))
parts. By using this notation Spring Cloud Contract allows you to
define parts of a JSON / URL / etc. which are dynamic. In case of an identifier or a timestamp you
don’t want to hardcode a value. You want to allow some different ranges of values. That’s why for
the consumer side you can set regular expressions matching those values. You can provide the body
either by means of a map notation or String with interpolations.
Consult the docs
for more information. We highly recommend using the map notation!
Tip
|
It’s really important that you understand the map notation to set up contracts. Please read the Groovy docs regarding JSON |
The aforementioned contract is an agreement between two sides that:
-
if an HTTP request is sent with
-
a method
PUT
on an endpoint/fraudcheck
-
JSON body with
clientPesel
matching the regular expression[0-9]{10}
andloanAmount
equal to99999
-
and with a header
Content-Type
equal toapplication/vnd.fraud.v1+json
-
-
then an HTTP response would be sent to the consumer that
-
has status
200
-
contains JSON body with the
fraudCheckStatus
field containing a valueFRAUD
and therejectionReason
field having valueAmount too high
-
and a
Content-Type
header with a value ofapplication/vnd.fraud.v1+json
-
Once we’re ready to check the API in practice in the integration tests we need to just install the stubs locally
add the Spring Cloud Contract Verifier plugin
We can add either Maven or Gradle plugin - in this example we’ll show how to add Maven. First we need to add the Spring Cloud Contract
BOM.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
Next, the Spring Cloud Contract Verifier
Maven plugin
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
</configuration>
</plugin>
Since the plugin was added we get the Spring Cloud Contract Verifier
features which from the provided contracts:
-
generate and run tests
-
produce and install stubs
We don’t want to generate tests since we, as consumers, want only to play with the stubs. That’s why we need to skip the tests generation and execution. When we execute:
cd local-http-server-repo
./mvnw clean install -DskipTests
In the logs we’ll see something like this:
[INFO] --- spring-cloud-contract-maven-plugin:1.0.0.BUILD-SNAPSHOT:generateStubs (default-generateStubs) @ http-server ---
[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar
[INFO]
[INFO] --- maven-jar-plugin:2.6:jar (default-jar) @ http-server ---
[INFO] Building jar: /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar
[INFO]
[INFO] --- spring-boot-maven-plugin:1.4.0.BUILD-SNAPSHOT:repackage (default) @ http-server ---
[INFO]
[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ http-server ---
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.jar
[INFO] Installing /some/path/http-server/pom.xml to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT.pom
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
This line is extremely important
[INFO] Installing /some/path/http-server/target/http-server-0.0.1-SNAPSHOT-stubs.jar to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
It’s confirming that the stubs of the http-server
have been installed in the local repository.
run the integration tests
In order to profit from the Spring Cloud Contract Stub Runner functionality of automatic stub downloading you have to do the following in our consumer side project (Loan Application service
).
Add the Spring Cloud Contract
BOM
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
Add the dependency to Spring Cloud Contract Stub Runner
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
<scope>test</scope>
</dependency>
Annotate your test class with @AutoConfigureStubRunner
. In the annotation provide the group id and artifact id for the Stub Runner to download stubs of your collaborators. Also provide the offline work switch since you’re playing with the collaborators offline (optional step).
@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment=WebEnvironment.NONE)
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:6565"}, workOffline = true)
@DirtiesContext
public class LoanApplicationServiceTests {
Now if you run your tests you’ll see sth like this:
2016-07-19 14:22:25.403 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Desired version is + - will try to resolve the latest version
2016-07-19 14:22:25.438 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved version is 0.0.1-SNAPSHOT
2016-07-19 14:22:25.439 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolving artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT using remote repositories []
2016-07-19 14:22:25.451 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Resolved artifact com.example:http-server:jar:stubs:0.0.1-SNAPSHOT to /path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar
2016-07-19 14:22:25.465 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacking stub from JAR [URI: file:/path/to/your/.m2/repository/com/example/http-server/0.0.1-SNAPSHOT/http-server-0.0.1-SNAPSHOT-stubs.jar]
2016-07-19 14:22:25.475 INFO 41050 --- [ main] o.s.c.c.stubrunner.AetherStubDownloader : Unpacked file to [/var/folders/0p/xwq47sq106x1_g3dtv6qfm940000gq/T/contracts100276532569594265]
2016-07-19 14:22:27.737 INFO 41050 --- [ main] o.s.c.c.stubrunner.StubRunnerExecutor : All stubs are now running RunningStubs [namesAndPorts={com.example:http-server:0.0.1-SNAPSHOT:stubs=8080}]
Which means that Stub Runner has found your stubs and started a server for app with group id com.example
, artifact id http-server
with version 0.0.1-SNAPSHOT
of the stubs and with stubs
classifier on port 8080
.
file a PR
What we did until now is an iterative process. We can play around with the contract, install it locally and work on the consumer side until we’re happy with the contract.
Once we’re satisfied with the results and the test passes publish a PR to the server side. Currently the consumer side work is done.
Producer side (Fraud Detection server)
As a developer of the Fraud Detection server (a server to the Loan Issuance service):
initial implementation
As a reminder here you can see the initial implementation
@RequestMapping(
value = "/fraudcheck",
method = PUT,
consumes = FRAUD_SERVICE_JSON_VERSION_1,
produces = FRAUD_SERVICE_JSON_VERSION_1)
public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
}
take over the PR
git checkout -b contract-change-pr master
git pull https://your-git-server.com/server-side-fork.git contract-change-pr
You have to add the dependencies needed by the autogenerated tests
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-contract-verifier</artifactId>
<scope>test</scope>
</dependency>
In the configuration of the Maven plugin we passed the packageWithBaseClasses
property
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
</configuration>
</plugin>
Important
|
We’ve decided to use the "convention based" naming by setting the packageWithBaseClasses property.
That means that 2 last packages will be combined into a name of the base test class. In our case the contracts
were placed under src/test/resources/contract/fraud . Since we don’t have 2 packages starting from the contracts
folder we’re picking only one which is fraud . We’re adding the Base suffix and we’re capitalizing fraud .
That gives us the FraudBase test class name.
|
That’s because all the generated tests will extend that class. Over there you can set up your Spring Context or
whatever is necessary. In our case we’re using Rest Assured MVC to start the server side FraudDetectionController
.
package com.example.fraud;
import com.example.fraud.FraudDetectionController;
import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc;
import org.junit.Before;
public class FraudBase {
@Before
public void setup() {
RestAssuredMockMvc.standaloneSetup(new FraudDetectionController());
}
public void assertThatRejectionReasonIsNull(Object rejectionReason) {
assert rejectionReason == null;
}
}
Now, if you run the ./mvnw clean install
you would get sth like this:
Results :
Tests in error:
ContractVerifierTest.validate_shouldMarkClientAsFraud:32 » IllegalState Parsed...
That’s because you have a new contract from which a test was generated and it failed since you haven’t implemented the feature. The autogenerated test would look like this:
@Test
public void validate_shouldMarkClientAsFraud() throws Exception {
// given:
MockMvcRequestSpecification request = given()
.header("Content-Type", "application/vnd.fraud.v1+json")
.body("{\"clientPesel\":\"1234567890\",\"loanAmount\":99999}");
// when:
ResponseOptions response = given().spec(request)
.put("/fraudcheck");
// then:
assertThat(response.statusCode()).isEqualTo(200);
assertThat(response.header("Content-Type")).matches("application/vnd.fraud.v1.json.*");
// and:
DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
assertThatJson(parsedJson).field("fraudCheckStatus").matches("[A-Z]{5}");
assertThatJson(parsedJson).field("rejectionReason").isEqualTo("Amount too high");
}
As you can see all the producer()
parts of the Contract that were present in the value(consumer(…), producer(…))
blocks got injected into the test.
What’s important here to note is that on the producer side we also are doing TDD. We have expectations in form of a test. This test is shooting a request to our own application to an URL, headers and body defined in the contract. It also is expecting very precisely defined values in the response. In other words you have is your red
part of red
, green
and refactor
. Time to convert the red
into the green
.
write the missing implementation
Now since we now what is the expected input and expected output let’s write the missing implementation.
@RequestMapping(
value = "/fraudcheck",
method = PUT,
consumes = FRAUD_SERVICE_JSON_VERSION_1,
produces = FRAUD_SERVICE_JSON_VERSION_1)
public FraudCheckResult fraudCheck(@RequestBody FraudCheck fraudCheck) {
if (amountGreaterThanThreshold(fraudCheck)) {
return new FraudCheckResult(FraudCheckStatus.FRAUD, AMOUNT_TOO_HIGH);
}
return new FraudCheckResult(FraudCheckStatus.OK, NO_REASON);
}
If we execute ./mvnw clean install
again the tests will pass. Since the Spring Cloud Contract Verifier
plugin adds the tests to the generated-test-sources
you can actually run those tests from your IDE.
deploy your app
Once you’ve finished your work it’s time to deploy your change. First merge the branch
git checkout master
git merge --no-ff contract-change-pr
git push origin master
Then we assume that your CI would run sth like ./mvnw clean deploy
which would publish both the application and the stub artifcats.
Consumer side (Loan Issuance) final step
As a developer of the Loan Issuance service (a consumer of the Fraud Detection server):
merge branch to master
git checkout master
git merge --no-ff contract-change-pr
work online
Now you can disable the offline work for Spring Cloud Contract Stub Runner ad provide where the repository with your stubs is placed. At this moment the stubs of the server side will be automatically downloaded from Nexus / Artifactory.
You can switch off the value of the workOffline
parameter in your annotation. Below you can see an
example of achieving the same by changing the properties.
stubrunner:
ids: 'com.example:http-server-dsl:+:stubs:8080'
repositoryRoot: http://repo.spring.io/libs-snapshot
And that’s it!
Dependencies
The best way to add the dependencies is to just use the proper starter
dependency.
For stub-runner
use spring-cloud-starter-stub-runner
and when you’re using a plugin just add
spring-cloud-starter-contract-verifier
.
Additional links
Below you can find some resources related to Spring Cloud Contract Verifier and Stub Runner. Note that some can be outdated since the Spring Cloud Contract Verifier project is under constant development.
Samples
Here you can find some samples.
FAQ
Why use Spring Cloud Contract Verifier and not X ?
For the time being Spring Cloud Contract Verifier is a JVM based tool. So it could be your first pick when you’re already creating software for the JVM. This project has a lot of really interesting features but especially quite a few of them definitely make Spring Cloud Contract Verifier stand out on the "market" of Consumer Driven Contract (CDC) tooling. Out of many the most interesting are:
-
Possibility to do CDC with messaging
-
Clear and easy to use, statically typed DSL
-
Possibility to copy paste your current JSON file to the contract and only edit its elements
-
Automatic generation of tests from the defined Contract
-
Stub Runner functionality - the stubs are automatically downloaded at runtime from Nexus / Artifactory
-
Spring Cloud integration - no discovery service is needed for integration tests
What is this value(consumer(), producer()) ?
One of the biggest challenges related to stubs is their reusability. Only if they can be vastly used, will they serve their purpose. What typically makes that difficult are the hard-coded values of request / response elements. For example dates or ids. Imagine the following JSON request
{
"time" : "2016-10-10 20:10:15",
"id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
"body" : "foo"
}
and JSON response
{
"time" : "2016-10-10 21:10:15",
"id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
"body" : "bar"
}
Imagine the pain required to set proper value of the time
field (let’s assume that this content is generated by the
database) by changing the clock in the system or providing stub implementations of data providers. The same is related
to the field called id
. Will you create a stubbed implementation of UUID generator? Makes little sense…
So as a consumer you would like to send a request that matches any form of a time or any UUID. That way your system
will work as usual - will generate data and you won’t have to stub anything out. Let’s assume that in case of the aforementioned
JSON the most important part is the body
field. You can focus on that and provide matching for other fields. In other words
you would like the stub to work like this:
{
"time" : "SOMETHING THAT MATCHES TIME",
"id" : "SOMETHING THAT MATCHES UUID",
"body" : "foo"
}
As far as the response goes as a consumer you need a concrete value that you can operate on. So such a JSON is valid
{
"time" : "2016-10-10 21:10:15",
"id" : "c4231e1f-3ca9-48d3-b7e7-567d55f0d051",
"body" : "bar"
}
As you could see in the previous sections we generate tests from contracts. So from the producer’s side the situation looks much different. We’re parsing the provided contract and in the test we want to send a real request to your endpoints. So for the case of a producer for the request we can’t have any sort of matching. We need concrete values that the producer’s backend can work on. Such a JSON would be a valid one:
{
"time" : "2016-10-10 20:10:15",
"id" : "9febab1c-6f36-4a0b-88d6-3b6a6d81cd4a",
"body" : "foo"
}
On the other hand from the point of view of the validity of the contract the response doesn’t necessarily have to
contain concrete values of time
or id
. Let’s say that you generate those on the producer side - again, you’d
have to do a lot of stubbing to ensure that you always return the same values. That’s why from the producer’s side
what you might want is the following response:
{
"time" : "SOMETHING THAT MATCHES TIME",
"id" : "SOMETHING THAT MATCHES UUID",
"body" : "bar"
}
How can you then provide one time a matcher for the consumer and a concrete value for the producer and vice versa? In Spring Cloud Contract we’re allowing you to provide a dynamic value. That means that it can differ for both sides of the communication. You can pass the values:
Either via the value
method
value(consumer(...), producer(...))
value(stub(...), test(...))
value(client(...), server(...))
or using the $()
method
$(consumer(...), producer(...))
$(stub(...), test(...))
$(client(...), server(...))
You can read more about this in the Contract DSL section.
Calling value()
or $()
tells Spring Cloud Contract that you will be passing a dynamic value.
Inside the consumer()
method you pass the value that should be used on the consumer side (in the generated stub).
Inside the producer()
method you pass the value that should be used on the producer side (in the generated test).
Tip
|
If on one side you have passed the regular expression and you haven’t passed the other, then the other side will get auto-generated. |
Most often you will use that method together with the regex
helper method. E.g. consumer(regex('[0-9]{10}'))
.
To sum it up the contract for the aforementioned scenario would look more or less like this (the regular expression for time and UUID are simplified and most likely invalid but we want to keep things very simple in this example):
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
url '/someUrl'
body([
time : value(consumer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
id: value(consumer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
body: "foo"
])
}
response {
status 200
body([
time : value(producer(regex('[0-9]{4}-[0-9]{2}-[0-9]{2} [0-2][0-9]-[0-5][0-9]-[0-5][0-9]')),
id: value([producer(regex('[0-9a-zA-z]{8}-[0-9a-zA-z]{4}-[0-9a-zA-z]{4}-[0-9a-zA-z]{12}'))
body: "bar"
])
}
}
Important
|
Please read the Groovy docs related to JSON to understand how to properly structure the request / response bodies. |
How to do Stubs versioning?
API Versioning
Let’s try to answer a question what versioning really means. If you’re referring to the API version then there are different approaches.
-
use Hypermedia, links and do not version your API by any means
-
pass versions through headers / urls
I will not try to answer a question which approach is better. Whatever suit your needs and allows you to generate business value should be picked.
Let’s assume that you do version your API. In that case you should provide as many contracts as many versions you support. You can create a subfolder for every version or append it to th contract name - whatever suits you more.
JAR versioning
If by versioning you mean the version of the JAR that contains the stubs then there are essentially two main approaches.
Let’s assume that you’re doing Continuous Delivery / Deployment which means that you’re generating a new version of the jar each time you go through the pipeline and that jar can go to production at any time. For example your jar version looks like this (it got built on the 20.10.2016 at 20:15:21) :
1.0.0.20161020-201521-RELEASE
In that case your generated stub jar will look like this.
1.0.0.20161020-201521-RELEASE-stubs.jar
In this case you should inside your application.yml
or @AutoConfigureStubRunner
when referencing stubs provide the
latest version of the stubs. You can do that by passing the +
sign. Example
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})
If the versioning however is fixed (e.g. 1.0.4.RELEASE
or 2.1.1
) then you have to set the concrete value of the jar
version. Example for 2.1.1.
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:2.1.1:stubs:8080"})
Dev or prod stubs
You can manipulate the classifier to run the tests against current development version of the stubs of other services
or the ones that were deployed to production. If you alter your build to deploy the stubs with the prod-stubs
classifier
once you reach production deployment then you can run tests in one case with dev stubs and one with prod stubs.
Example of tests using development version of stubs
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:stubs:8080"})
Example of tests using production version of stubs
@AutoConfigureStubRunner(ids = {"com.example:http-server-dsl:+:prod-stubs:8080"})
You can pass those values also via properties from your deployment pipeline.
Common repo with contracts
Another way of storing contracts other than having them with the producer is keeping them in a common place. It can be related to security issues where the consumers can’t clone the producer’s code. Also if you keep contracts in a single place then you, as a producer, will know how many consumers you have and which consumer will you break with your local changes.
Repo structure
Let’s assume that we have a producer with coordinates com.example:server
and 3 consumers: client1
,
client2
, client3
. Then in the repository with common contracts you would have the following setup
(which you can checkout here:
├── com
│  └── example
│  └── server
│  ├── client1
│  │  └── expectation.groovy
│  ├── client2
│  │  └── expectation.groovy
│  ├── client3
│  │  └── expectation.groovy
│  └── pom.xml
├── mvnw
├── mvnw.cmd
├── pom.xml
└── src
└── assembly
└── contracts.xml
As you can see the under the slash-delimited groupid /
artifact id folder (com/example/server
) you have
expectations of the 3 consumers (client1
, client2
and client3
). Expectations are the standard Groovy DSL
contract files as described throughout this documentation. This repository has to produce a JAR file that maps
one to one to the contents of the repo.
Example of a pom.xml
inside the server
folder.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>server</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Server Stubs</name>
<description>POM used to install locally stubs for consumer side</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.2.BUILD-SNAPSHOT</version>
<relativePath />
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<spring-cloud-contract.version>1.0.6.BUILD-SNAPSHOT</spring-cloud-contract.version>
<spring-cloud-dependencies.version>Camden.BUILD-SNAPSHOT</spring-cloud-dependencies.version>
<excludeBuildFolders>true</excludeBuildFolders>
</properties>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<!-- By default it would search under src/test/resources/ -->
<contractsDirectory>${project.basedir}</contractsDirectory>
</configuration>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>
As you can see there are no dependencies other than the Spring Cloud Contract Maven Plugin.
Those poms are necessary for the consumer side to run mvn clean install -DskipTests
to locally install
stubs of the producer project.
The pom.xml
in the root folder can look like this:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example.standalone</groupId>
<artifactId>contracts</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>Contracts</name>
<description>Contains all the Spring Cloud Contracts, well, contracts. JAR used by the producers to generate tests and stubs</description>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<id>contracts</id>
<phase>prepare-package</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<attach>true</attach>
<descriptor>${basedir}/src/assembly/contracts.xml</descriptor>
<!-- If you want an explicit classifier remove the following line -->
<appendAssemblyId>false</appendAssemblyId>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
It’s using the assembly plugin in order to build the JAR with all the contracts. Example of such setup is here:
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 http://maven.apache.org/xsd/assembly-1.1.3.xsd">
<id>project</id>
<formats>
<format>jar</format>
</formats>
<includeBaseDirectory>false</includeBaseDirectory>
<fileSets>
<fileSet>
<directory>${project.basedir}</directory>
<outputDirectory>/</outputDirectory>
<useDefaultExcludes>true</useDefaultExcludes>
<excludes>
<exclude>**/${project.build.directory}/**</exclude>
<exclude>mvnw</exclude>
<exclude>mvnw.cmd</exclude>
<exclude>.mvn/**</exclude>
<exclude>src/**</exclude>
</excludes>
</fileSet>
</fileSets>
</assembly>
Workflow
The workflow would look similar to the one presented in the Step by step guide to CDC
. The only difference
is that the producer doesn’t own the contracts anymore. So the consumer and the producer have to work on
common contracts in a common repository.
Consumer
When the consumer wants to work on the contracts offline, instead of cloning the producer code, the
consumer team clones the common repository, goes to the required producer’s folder (e.g. com/example/server
)
and runs mvn clean install -DskipTests
to install locally the stubs converted from the contracts.
Tip
|
You need to have Maven installed locally |
Producer
As a producer it’s enough to alter the Spring Cloud Contract Verifier to provide the URL and the dependency of the JAR containing the contracts:
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<configuration>
<contractsRepositoryUrl>http://link/to/your/nexus/or/artifactory/or/sth</contractsRepositoryUrl>
<contractDependency>
<groupId>com.example.standalone</groupId>
<artifactId>contracts</artifactId>
</contractDependency>
</configuration>
</plugin>
With this setup the JAR with groupid com.example.standalone
and artifactid contracts
will be downloaded
from http://link/to/your/nexus/or/artifactory/or/sth
. It will be then unpacked in a local temporary folder
and contracts present under the com/example/server
will be picked as the ones used to generate the
tests and the stubs. Due to this convention the producer team will know which consumer teams will be broken
when some incompatible changes are done.
The rest of the flow looks the same.
Can I have multiple base classes for tests?
Yes! Check out the Different base classes for contracts sections of either Gradle or Maven plugins.
How can I debug the request/response being sent by the generated tests client?
The generated tests all boil down to RestAssured in some form or fashion which relies on Apache HttpClient. HttpClient has a facility called wire logging which logs the entire request and response to HttpClient. Spring Boot has a logging common application property for doing this sort of thing, just add this to your application properties
logging.level.org.apache.http.wire=DEBUG
Spring Cloud Contract Verifier HTTP
Gradle Project
Prerequisites
In order to use Spring Cloud Contract Verifier with WireMock you have to use Gradle or Maven plugin.
Warning
|
If you want to use Spock in your projects you have to add separately
the spock-core and spock-spring modules. Check Spock docs for more information
|
Add gradle plugin with dependencies
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
}
}
apply plugin: 'groovy'
apply plugin: 'spring-cloud-contract'
dependencyManagement {
imports {
mavenBom "org.springframework.cloud:spring-cloud-contract-dependencies:${verifier_version}"
}
}
dependencies {
testCompile 'org.codehaus.groovy:groovy-all:2.4.6'
// example with adding Spock core and Spock Spring
testCompile 'org.spockframework:spock-core:1.0-groovy-2.4'
testCompile 'org.spockframework:spock-spring:1.0-groovy-2.4'
testCompile 'org.springframework.cloud:spring-cloud-starter-contract-verifier'
}
Gradle and Rest Assured 3.0
By default Rest Assured 2.x is added to the classpath. However in order to give the users the opportunity to use Rest Assured 3.x it’s enough to add it to the plugins classpath.
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath "org.springframework.boot:spring-boot-gradle-plugin:${springboot_version}"
classpath "org.springframework.cloud:spring-cloud-contract-gradle-plugin:${verifier_version}"
classpath "io.rest-assured:rest-assured:3.0.2"
classpath "io.rest-assured:spring-mock-mvc:3.0.2"
}
}
depenendencies {
// all dependencies
// you can exclude rest-assured from spring-cloud-contract-verifier
testCompile "io.rest-assured:rest-assured:3.0.2"
testCompile "io.rest-assured:spring-mock-mvc:3.0.2"
}
That way the plugin will automatically see that Rest Assured 3.x is present on the classpath and will modify the imports accordingly.
Snapshot versions for Gradle
Add the additional snapshot repository to your build.gradle to use snapshot versions which are automatically uploaded after every successful build:
buildscript {
repositories {
mavenCentral()
mavenLocal()
maven { url "http://repo.spring.io/snapshot" }
maven { url "http://repo.spring.io/milestone" }
maven { url "http://repo.spring.io/release" }
}
}
Add stubs
By default Spring Cloud Contract Verifier is looking for stubs in src/test/resources/contracts
directory.
Directory containing stub definitions is treated as a class name, and each stub definition is treated as a single test. We assume that it contains at least one directory which will be used as test class name. If there is more than one level of nested directories all except the last one will be used as package name. So with following structure
src/test/resources/contracts/myservice/shouldCreateUser.groovy
src/test/resources/contracts/myservice/shouldReturnUser.groovy
Spring Cloud Contract Verifier will create test class defaultBasePackage.MyService
with two methods
-
shouldCreateUser()
-
shouldReturnUser()
Run plugin
Plugin registers itself to be invoked before check
task. You have nothing to do as long as you want it to be part of your build process. If you just want to generate tests please invoke generateContractTests
task.
Default setup
Default Gradle Plugin setup creates the following Gradle part of the build (it’s a pseudocode)
contracts {
targetFramework = 'JUNIT'
testMode = 'MockMvc'
generatedTestSourcesDir = project.file("${project.buildDir}/generated-test-sources/contracts")
contractsDslDir = "${project.rootDir}/src/test/resources/contracts"
basePackageForTests = 'org.springframework.cloud.verifier.tests'
stubsOutputDir = project.file("${project.buildDir}/stubs")
// the following properties are used when you want to provide where the JAR with contract lays
contractDependency {
stringNotation = ''
}
contractsPath = ''
contractsWorkOffline = false
}
tasks.create(type: Jar, name: 'verifierStubsJar', dependsOn: 'generateWireMockClientStubs') {
baseName = project.name
classifier = contracts.stubsSuffix
from contractVerifier.stubsOutputDir
}
project.artifacts {
archives task
}
tasks.create(type: Copy, name: 'copyContracts') {
from contracts.contractsDslDir
into contracts.stubsOutputDir
}
verifierStubsJar.dependsOn 'copyContracts'
publishing {
publications {
stubs(MavenPublication) {
artifactId project.name
artifact verifierStubsJar
}
}
}
Configure plugin
To change default configuration just add contracts
snippet to your Gradle config
contracts {
testMode = 'MockMvc'
baseClassForTests = 'org.mycompany.tests'
generatedTestSourcesDir = project.file('src/generatedContract')
}
Configuration options
-
testMode - defines mode for acceptance tests. By default MockMvc which is based on Spring’s MockMvc. It can also be changed to JaxRsClient or to Explicit for real HTTP calls.
-
imports - array with imports that should be included in generated tests (for example ['org.myorg.Matchers']). By default empty array []
-
staticImports - array with static imports that should be included in generated tests(for example ['org.myorg.Matchers.*']). By default empty array []
-
basePackageForTests - specifies base package for all generated tests. By default set to org.springframework.cloud.verifier.tests
-
baseClassForTests - base class for all generated tests. By default
spock.lang.Specification
if using Spock tests. -
packageWithBaseClasses - instead of providing a fixed value for base class you can provide a package where all the base classes lay. Takes precedence over baseClassForTests.
-
baseClassMappings - explicitly map contract package to a FQN of a base class. Takes precedence over packageWithBaseClasses and baseClassForTests.
-
ruleClassForTests - specifies Rule which should be added to generated test classes.
-
ignoredFiles - Ant matcher allowing defining stub files for which processing should be skipped. By default empty array []
-
contractsDslDir - directory containing contracts written using the GroovyDSL. By default
$rootDir/src/test/resources/contracts
-
generatedTestSourcesDir - test source directory where tests generated from Groovy DSL should be placed. By default
$buildDir/generated-test-sources/contractVerifier
-
stubsOutputDir - dir where the generated WireMock stubs from Groovy DSL should be placed
-
targetFramework - the target test framework to be used; currently Spock and JUnit are supported with JUnit being the default framework
The following properties are used when you want to provide where the JAR with contract lays
-
contractDependency - the Dependency that provides
groupid:artifactid:version:classifier
coordinates. You can use thecontractDependency
closure to set it up -
contractsPath - if contract deps are downloaded will default to
groupid/artifactid
wheregroupid
will be slash separated. Otherwise will scan contracts under provided directory -
contractsWorkOffline - in order not to download the dependencies each time you can download them once and work offline afterwards (reuse local Maven repo)
Single base class for all tests
When using Spring Cloud Contract Verifier in default MockMvc you need to create a base specification for all generated acceptance tests. In this class you need to point to endpoint which should be verified.
abstract class BaseMockMvcSpec extends Specification {
def setup() {
RestAssuredMockMvc.standaloneSetup(new PairIdController())
}
void isProperCorrelationId(Integer correlationId) {
assert correlationId == 123456
}
void isEmpty(String value) {
assert value == null
}
}
In case of using Explicit
mode, you can use base class to initialize the whole tested app similarly as in regular integration tests. In case of JAXRSCLIENT
mode this base class
should also contain protected WebTarget webTarget
field, right now the only option to test JAX-RS API is to start a web server.
Different base classes for contracts
If your base classes differ between contracts you can tell the Spring Cloud Contract plugin which class should get extended by the autogenerated tests. You have two options:
-
follow a convention by providing the
packageWithBaseClasses
-
provide explicit mapping via
baseClassMappings
Convention
The convention is such that if you have a contract under e.g. src/test/resources/contract/foo/bar/baz/
and provide the value of the packageWithBaseClasses
property
to com.example.base
then we will assume that there is a BarBazBase
class under com.example.base
package. In other words we take last two parts of package
if they exist and form a class with a Base
suffix. Takes precedence over baseClassForTests. Example of usage in the contracts
closure:
packageWithBaseClasses = 'com.example.base'
Mapping
You can manually map a regular expression of the contract’s package to fully qualified name of the base class for the matched contract. Let’s take a look at the following example:
baseClassForTests = "com.example.FooBase"
baseClassMappings {
baseClassMapping('.*/com/.*', 'com.example.ComBase')
baseClassMapping('.*/bar/.*':'com.example.BarBase')
}
Let’s assume that you have contracts under
- src/test/resources/contract/com/
- src/test/resources/contract/foo/
By providing the baseClassForTests
we have a fallback in case mapping didn’t succeed (you could also provide
the packageWithBaseClasses
as fallback). That way the tests generated from src/test/resources/contract/com/
contracts
will be extending the com.example.ComBase
whereas the rest of tests will extend com.example.FooBase
.
Invoking generated tests
To ensure that provider side is complaint with defined contracts, you need to invoke:
./gradlew generateContractTests test
Spring Cloud Contract Verifier on consumer side
In consumer service you need to configure Spring Cloud Contract Verifier plugin in exactly the same way as in case of provider. If you don’t want to use Stub Runner then you need to copy contracts stored in
src/test/resources/contracts
and generate WireMock json stubs using:
./gradlew generateWireMockClientStubs
Note that stubsOutputDir
option has to be set for stub generation to work.
When present, json stubs can be used in consumer automated tests.
@ContextConfiguration(loader == SpringApplicationContextLoader, classes == Application)
class LoanApplicationServiceSpec extends Specification {
@ClassRule
@Shared
WireMockClassRule wireMockRule == new WireMockClassRule()
@Autowired
LoanApplicationService sut
def 'should successfully apply for loan'() {
given:
LoanApplication application =
new LoanApplication(client: new Client(clientPesel: '12345678901'), amount: 123.123)
when:
LoanApplicationResult loanApplication == sut.loanApplication(application)
then:
loanApplication.loanApplicationStatus == LoanApplicationStatus.LOAN_APPLIED
loanApplication.rejectionReason == null
}
}
Underneath LoanApplication makes a call to FraudDetection service. This request is handled by WireMock server configured using stubs generated by Spring Cloud Contract Verifier.
Using in your Maven project
Add maven plugin
Add the Spring Cloud Contract BOM
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud-dependencies.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
Next, the Spring Cloud Contract Verifier
Maven plugin
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example.fraud</packageWithBaseClasses>
</configuration>
</plugin>
You can read more in the Spring Cloud Contract Maven Plugin Docs
Maven and Rest Assured 3.0
By default Rest Assured 2.x is added to the classpath. However in order to give the users the opportunity to use Rest Assured 3.x it’s enough to add it to the plugins classpath.
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example</packageWithBaseClasses>
</configuration>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-verifier</artifactId>
<version>${spring-cloud-contract.version}</version>
</dependency>
<dependency>
<groupId>io.rest-assured</groupId>
<artifactId>rest-assured</artifactId>
<version>3.0.2</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>io.rest-assured</groupId>
<artifactId>spring-mock-mvc</artifactId>
<version>3.0.2</version>
<scope>compile</scope>
</dependency>
</dependencies>
</plugin>
<dependencies>
<!-- all dependencies -->
<!-- you can exclude rest-assured from spring-cloud-contract-verifier -->
<dependency>
<groupId>io.rest-assured</groupId>
<artifactId>rest-assured</artifactId>
<version>3.0.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.rest-assured</groupId>
<artifactId>spring-mock-mvc</artifactId>
<version>3.0.2</version>
<scope>test</scope>
</dependency>
</dependencies>
That way the plugin will automatically see that Rest Assured 3.x is present on the classpath and will modify the imports accordingly.
Snapshot versions for Maven
For Snapshot / Milestone versions you have to add the following section to your pom.xml
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
Add stubs
By default Spring Cloud Contract Verifier is looking for stubs in src/test/resources/contracts
directory.
Directory containing stub definitions is treated as a class name, and each stub definition is treated as a single test.
We assume that it contains at least one directory which will be used as test class name. If there is more than one level of nested directories all except the last one will be used as package name.
So with following structure
src/test/resources/contracts/myservice/shouldCreateUser.groovy
src/test/resources/contracts/myservice/shouldReturnUser.groovy
Spring Cloud Contract Verifier will create test class defaultBasePackage.MyService
with two methods
- shouldCreateUser()
- shouldReturnUser()
Run plugin
Plugin goal generateTests
is assigned to be invoked in phase generate-test-sources
. You have nothing to do as long as you want it to be part of your build process. If you just want to generate tests please invoke generateTests
goal.
Configure plugin
To change default configuration just add configuration
section to plugin definition or execution
definition.
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>convert</goal>
<goal>generateStubs</goal>
<goal>generateTests</goal>
</goals>
</execution>
</executions>
<configuration>
<basePackageForTests>org.springframework.cloud.verifier.twitter.place</basePackageForTests>
<baseClassForTests>org.springframework.cloud.verifier.twitter.place.BaseMockMvcSpec</baseClassForTests>
</configuration>
</plugin>
Important configuration options
-
testMode - defines mode for acceptance tests. By default
MockMvc
which is based on Spring’s MockMvc. It can also be changed toJaxRsClient
or toExplicit
for real HTTP calls. -
basePackageForTests - specifies base package for all generated tests. By default set to
org.springframework.cloud.verifier.tests
. -
ruleClassForTests - specifies Rule which should be added to generated test classes.
-
baseClassForTests - base class for generated tests. By default
spock.lang.Specification
if using Spock tests. -
contractsDir - directory containing contracts written using the GroovyDSL. By default
/src/test/resources/contracts
. -
testFramework - the target test framework to be used; currently Spock and JUnit are supported with JUnit being the default framework
-
packageWithBaseClasses - instead of providing a fixed value for base class you can provide a package where all the base classes lay. The convention is such that if you have a contract under
src/test/resources/contract/foo/bar/baz/
and provide the value of this property tocom.example.base
then we will assume that there is aBarBazBase
class undercom.example.base
package. Takes precedence over baseClassForTests -
baseClassMappings - list of base class mappings that where you have to provide
contractPackageRegex
which is checked against the package in which the contract lays andbaseClassFQN
that maps to fully qualified name of the base class for the matched contract. If you have a contract undersrc/test/resources/contract/foo/bar/baz/
and map the property.*
→com.example.base.BaseClass
then the test class generated from these contracts will extendcom.example.base.BaseClass
. Takes precedence over packageWithBaseClasses and baseClassForTests.
If you want to download your contract definitions from a Maven repository you can use
-
contractsRepositoryUrl - URL to a repo with the artifacts with contracts, if not provided should use the current Maven ones
-
contractDependency - the contract dependency that contains all the packaged contracts
-
contractsPath - path to concrete contracts in the JAR with packaged contracts. Defaults to
groupid/artifactid
wheregropuid
is slash separated. -
contractsWorkOffline - if the dependencies should be downloaded or local Maven only should be reused
For complete information take a look at Plugin Documentation
Single base class for all tests
When using Spring Cloud Contract Verifier in default MockMvc you need to create a base specification for all generated acceptance tests. In this class you need to point to endpoint which should be verified.
package org.mycompany.tests
import org.mycompany.ExampleSpringController
import com.jayway.restassured.module.mockmvc.RestAssuredMockMvc
import spock.lang.Specification
class MvcSpec extends Specification {
def setup() {
RestAssuredMockMvc.standaloneSetup(new ExampleSpringController())
}
}
In case of using Explicit
mode, you can use base class to initialize the whole tested app similarly as in regular integration tests. In case of JAXRSCLIENT
mode this base class should also contain protected WebTarget webTarget
field, right now the only option to test JAX-RS API is to start a web server.
Different base classes for contracts
If your base classes differ between contracts you can tell the Spring Cloud Contract plugin which class should get extended by the autogenerated tests. You have two options:
-
follow a convention by providing the
packageWithBaseClasses
-
provide explicit mapping via
baseClassMappings
Convention
The convention is such that if you have a contract under e.g. src/test/resources/contract/hello/v1/
and provide the value of the packageWithBaseClasses
property
to hello
then we will assume that there is a HelloV1Base
class under hello
package. In other words we take last two parts of package
if they exist and form a class with a Base
suffix. Takes precedence over baseClassForTests. Example of usage:
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<configuration>
<packageWithBaseClasses>hello</packageWithBaseClasses>
</configuration>
</plugin>
Mapping
You can manually map a regular expression of the contract’s package to fully qualified name of the base class for the matched contract.
You have to provide a list baseClassMappings
of baseClassMapping
that takes a contractPackageRegex
to baseClassFQN
mapping.
Let’s take a look at the following example:
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<configuration>
<baseClassForTests>com.example.FooBase</baseClassForTests>
<baseClassMappings>
<baseClassMapping>
<contractPackageRegex>.*com.*</contractPackageRegex>
<baseClassFQN>com.example.TestBase</baseClassFQN>
</baseClassMapping>
</baseClassMappings>
</configuration>
</plugin>
Let’s assume that you have contracts under
- src/test/resources/contract/com/
- src/test/resources/contract/foo/
By providing the baseClassForTests
we have a fallback in case mapping didn’t succeed (you could also provide
the packageWithBaseClasses
as fallback). That way the tests generated from src/test/resources/contract/com/
contracts
will be extending the com.example.ComBase
whereas the rest of tests will extend com.example.FooBase
.
Invoking generated tests
Spring Cloud Contract Maven Plugin generates verification code into directory /generated-test-sources/contractVerifier
and attach this directory to testCompile
goal.
For Groovy Spock code use:
<plugin>
<groupId>org.codehaus.gmavenplus</groupId>
<artifactId>gmavenplus-plugin</artifactId>
<version>1.5</version>
<executions>
<execution>
<goals>
<goal>testCompile</goal>
</goals>
</execution>
</executions>
<configuration>
<testSources>
<testSource>
<directory>${project.basedir}/src/test/groovy</directory>
<includes>
<include>**/*.groovy</include>
</includes>
</testSource>
<testSource>
<directory>${project.build.directory}/generated-test-sources/contractVerifier</directory>
<includes>
<include>**/*.groovy</include>
</includes>
</testSource>
</testSources>
</configuration>
</plugin>
To ensure that provider side is complaint with defined contracts, you need to invoke mvn generateTest test
FAQ with Maven Plugin
Maven Plugin and STS
In case you see the following exception while using STS
when you click on the marker you should see sth like this
plugin:1.1.0.M1:convert:default-convert:process-test-resources) org.apache.maven.plugin.PluginExecutionException: Execution default-convert of goal org.springframework.cloud:spring-
cloud-contract-maven-plugin:1.1.0.M1:convert failed. at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145) at
org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331) at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362) at
...
org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.lang.NullPointerException at
org.eclipse.m2e.core.internal.builder.plexusbuildapi.EclipseIncrementalBuildContext.hasDelta(EclipseIncrementalBuildContext.java:53) at
org.sonatype.plexus.build.incremental.ThreadBuildContext.hasDelta(ThreadBuildContext.java:59) at
In order to fix this issue just provide the following section in your pom.xml
<build>
<pluginManagement>
<plugins>
<!--This plugin's configuration is used to store Eclipse m2e settings
only. It has no influence on the Maven build itself. -->
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<versionRange>[1.0,)</versionRange>
<goals>
<goal>convert</goal>
</goals>
</pluginExecutionFilter>
<action>
<execute />
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
Spring Cloud Contract Verifier on consumer side
You can actually use the Spring Cloud Contract Verifier also for the consumer side!
You can use the plugin so that it only converts the contracts and generates the stubs.
To achieve that you need to configure Spring Cloud Contract Verifier plugin in exactly
the same way as in case of provider. You need to copy contracts stored in
src/test/resources/contracts
and generate WireMock json stubs using:
mvn generateStubs
command. By default generated WireMock mapping is
stored in directory target/mappings
. Your project should create from
this generated mappings additional artifact with classifier stubs
for
easy deploy to maven repository.
Sample configuration:
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${verifier-plugin.version}</version>
<executions>
<execution>
<goals>
<goal>convert</goal>
<goal>generateStubs</goal>
</goals>
</execution>
</executions>
</plugin>
When present, json stubs can be used in consumer automated tests.
@RunWith(SpringTestRunner.class)
@SpringBootTest
@AutoConfigureStubRunner
public class LoanApplicationServiceTests {
@Autowired
LoanApplicationService service;
@Test
public void shouldSuccessfullyApplyForLoan() {
//given:
LoanApplication application =
new LoanApplication(new Client("12345678901"), 123.123);
//when:
LoanApplicationResult loanApplication = service.loanApplication(application);
// then:
assertThat(loanApplication.loanApplicationStatus).isEqualTo(LoanApplicationStatus.LOAN_APPLIED);
assertThat(loanApplication.rejectionReason).isNull();
}
}
Underneath LoanApplication
makes a call to the FraudDetection
service. This request is handled by
a WireMock server configured using stubs generated by Spring Cloud Contract Verifier.
Scenarios
It’s possible to handle scenarios with Spring Cloud Contract Verifier. All you need to do is to stick to proper naming convention while creating your contracts. The convention requires to include order number followed by the underscore.
my_contracts_dir\
scenario1\
1_login.groovy
2_showCart.groovy
3_logout.groovy
Such tree will cause Spring Cloud Contract Verifier generating WireMock’s scenario with name scenario1
and three steps:
-
login marked as
Started
pointing to: -
showCart marked as
Step1
pointing to: -
logout marked as
Step2
which will close the scenario.
More details about WireMock scenarios can be found under http://wiremock.org/stateful-behaviour.html
Spring Cloud Contract Verifier will also generate tests with guaranteed order of execution.
Stubs and transitive dependencies
The Maven and Gradle plugin that we’re created are adding the tasks that create the stubs jar for you. What can be problematic is that when reusing the stubs you can by mistake import all of that stub dependencies! When building a Maven artifact even though you have a couple of different jars, all of them share one pom:
├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar
├── github-webhook-0.0.1.BUILD-20160903.075506-1-stubs.jar.sha1
├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar
├── github-webhook-0.0.1.BUILD-20160903.075655-2-stubs.jar.sha1
├── github-webhook-0.0.1.BUILD-SNAPSHOT.jar
├── github-webhook-0.0.1.BUILD-SNAPSHOT.pom
├── github-webhook-0.0.1.BUILD-SNAPSHOT-stubs.jar
├── ...
└── ...
There are three possibilities of working with those dependencies so as not to have any issues with transitive dependencies.
Mark all application dependencies as optional
If in the github-webhook
application we would mark all of our dependencies as optional, when you include the
github-webhook
stubs in another application (or when that dependency gets downloaded by Stub Runner) then, since
all of the depenencies are optional, they will not get downloaded.
Create a separate artifactid for stubs
If you create a separate artifactid then you can set it up in whatever way you wish. For example by having no dependencies at all.
Exclude dependencies on the consumer side
As a consumer, if you add the stub dependency to your classpath you can explicitly exclude the unwanted dependencies.
Spring Cloud Contract Verifier Messaging
Spring Cloud Contract Verifier allows you to verify your application that uses messaging as means of communication. All of our integrations are working with Spring but you can also create one yourself and use it.
Integrations
You can use one of the four integration configurations:
-
Apache Camel
-
Spring Integration
-
Spring Cloud Stream
-
Spring AMQP
Since we’re using Spring Boot then if you have added one of the aforementioned libraries to the classpath then automatically all the messaging configuration will be set up.
Important
|
Remember to put @AutoConfigureMessageVerifier on the base class of your
generated tests. Otherwise messaging part of Spring Cloud Contract Verifier will not work.
|
Manual Integration Testing
The main interface used by the tests is the org.springframework.cloud.contract.verifier.messaging.MessageVerifier
.
It defines how to send and receive messages. You can create your own implementation to achieve the
same goal.
In the a test you can inject a ContractVerifierMessageExchange
to send and receive messages that follow the contract.
Then add @AutoConfigureMessageVerifier
to your test, e.g.
@RunWith(SpringTestRunner.class)
@SpringBootTest
@AutoConfigureMessageVerifier
public static class MessagingContractTests {
@Autowired
private MessageVerifier verifier;
...
}
Note
|
If your tests require stubs as well, then
@AutoConfigureStubRunner includes the messaging configuration, so
you only need the one annotation.
|
Publisher side test generation
Having the input
or outputMessage
sections in your DSL will result in creation of tests on the publisher’s side. By default
JUnit tests will be created, however there is also a possibility to create Spock tests.
There are 3 main scenarios that we should take into consideration:
-
Scenario 1: there is no input message that produces an output one. The output message is triggered by a component inside the application (e.g. scheduler)
-
Scenario 2: the input message triggers an output message
-
Scenario 3: the input message is consumed and there is no output message
Scenario 1 (no input message)
For the given contract:
def contractDsl = Contract.make {
label 'some_label'
input {
triggeredBy('bookReturnedTriggered()')
}
outputMessage {
sentTo('activemq:output')
body('''{ "bookName" : "foo" }''')
headers {
header('BOOK-NAME', 'foo')
}
}
}
The following JUnit test will be created:
'''
// when:
bookReturnedTriggered();
// then:
ContractVerifierMessage response = contractVerifierMessaging.receive("activemq:output");
assertThat(response).isNotNull();
assertThat(response.getHeader("BOOK-NAME")).isEqualTo("foo");
// and:
DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
'''
And the following Spock test would be created:
'''
when:
bookReturnedTriggered()
then:
ContractVerifierMessage response = contractVerifierMessaging.receive('activemq:output')
assert response != null
response.getHeader('BOOK-NAME') == 'foo'
and:
DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
'''
Scenario 2 (output triggered by input)
For the given contract:
def contractDsl = Contract.make {
label 'some_label'
input {
messageFrom('jms:input')
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo('jms:output')
body([
bookName: 'foo'
])
headers {
header('BOOK-NAME', 'foo')
}
}
}
The following JUnit test will be created:
'''
// given:
ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
"{\\"bookName\\":\\"foo\\"}"
, headers()
.header("sample", "header"));
// when:
contractVerifierMessaging.send(inputMessage, "jms:input");
// then:
ContractVerifierMessage response = contractVerifierMessaging.receive("jms:output");
assertThat(response).isNotNull();
assertThat(response.getHeader("BOOK-NAME")).isEqualTo("foo");
// and:
DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.getPayload()));
assertThatJson(parsedJson).field("bookName").isEqualTo("foo");
'''
And the following Spock test would be created:
"""\
given:
ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
'''{"bookName":"foo"}''',
['sample': 'header']
)
when:
contractVerifierMessaging.send(inputMessage, 'jms:input')
then:
ContractVerifierMessage response = contractVerifierMessaging.receive('jms:output')
assert response !- null
response.getHeader('BOOK-NAME') == 'foo'
and:
DocumentContext parsedJson = JsonPath.parse(contractVerifierObjectMapper.writeValueAsString(response.payload))
assertThatJson(parsedJson).field("bookName").isEqualTo("foo")
"""
Scenario 3 (no output message)
For the given contract:
def contractDsl = Contract.make {
label 'some_label'
input {
messageFrom('jms:delete')
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
assertThat('bookWasDeleted()')
}
}
The following JUnit test will be created:
'''
// given:
ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
"{\\"bookName\\":\\"foo\\"}"
, headers()
.header("sample", "header"));
// when:
contractVerifierMessaging.send(inputMessage, "jms:delete");
// then:
bookWasDeleted();
'''
And the following Spock test would be created:
'''
given:
ContractVerifierMessage inputMessage = contractVerifierMessaging.create(
\'\'\'{"bookName":"foo"}\'\'\',
['sample': 'header']
)
when:
contractVerifierMessaging.send(inputMessage, 'jms:delete')
then:
noExceptionThrown()
bookWasDeleted()
'''
Consumer Stub Side generation
Unlike the HTTP part - in Messaging we need to publish the Groovy DSL inside the JAR with a stub. Then it’s parsed on the consumer side and proper stubbed routes are created.
For more information please consult the Stub Runner Messaging sections.
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-stream-rabbit</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-contract-stub-runner</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-stream-test-support</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Camden.BUILD-SNAPSHOT</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
ext {
contractsDir = file("mappings")
stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
}
// Automatically added by plugin:
// copyContracts - copies contracts to the output folder from which JAR will be created
// verifierStubsJar - JAR with a provided stub suffix
// the presented publication is also added by the plugin but you can modify it as you wish
publishing {
publications {
stubs(MavenPublication) {
artifactId "${project.name}-stubs"
artifact verifierStubsJar
}
}
}
Spring Cloud Contract Stub Runner
One of the issues that you could have encountered while using Spring Cloud Contract Verifier was to pass the generated WireMock JSON stubs from the server side to the client side (or various clients). The same takes place in terms of client side generation for messaging.
Copying the JSON files / setting the client side for messaging manually is out of the question.
That’s why we’ll introduce Spring Cloud Contract Stub Runner that can download and run the stubs automatically for you.
Snapshot versions
Add the additional snapshot repository to your build.gradle to use snapshot versions which are automatically uploaded after every successful build:
<repositories>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-releases</id>
<name>Spring Releases</name>
<url>https://repo.spring.io/release</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
buildscript {
repositories {
mavenCentral()
mavenLocal()
maven { url "http://repo.spring.io/snapshot" }
maven { url "http://repo.spring.io/milestone" }
maven { url "http://repo.spring.io/release" }
}
Publishing stubs as JARs
The easiest approach would be to centralize the way stubs are kept. For example you can keep them as JARs in a Maven repository.
Tip
|
For both Maven and Gradle the setup comes out of the box. But you can customize it if you want to. |
<!-- First disable the default jar setup in the properties section-->
<!-- we don't want the verifier to do a jar for us -->
<spring.cloud.contract.verifier.skip>true</spring.cloud.contract.verifier.skip>
<!-- Next add the assembly plugin to your build -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<id>stub</id>
<phase>prepare-package</phase>
<goals>
<goal>single</goal>
</goals>
<inherited>false</inherited>
<configuration>
<attach>true</attach>
<descriptor>$/Users/ryanjbaxter/git-repos/spring-cloud/scripts/docs/../src/assembly/stub.xml</descriptor>
</configuration>
</execution>
</executions>
</plugin>
<!-- Finally setup your assembly. Below you can find the contents of src/main/assembly/stub.xml -->
<assembly
xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.3 http://maven.apache.org/xsd/assembly-1.1.3.xsd">
<id>stubs</id>
<formats>
<format>jar</format>
</formats>
<includeBaseDirectory>false</includeBaseDirectory>
<fileSets>
<fileSet>
<directory>src/main/java</directory>
<outputDirectory>/</outputDirectory>
<includes>
<include>**com/example/model/*.*</include>
</includes>
</fileSet>
<fileSet>
<directory>${project.build.directory}/classes</directory>
<outputDirectory>/</outputDirectory>
<includes>
<include>**com/example/model/*.*</include>
</includes>
</fileSet>
<fileSet>
<directory>${project.build.directory}/snippets/stubs</directory>
<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/mappings</outputDirectory>
<includes>
<include>**/*</include>
</includes>
</fileSet>
<fileSet>
<directory>$/Users/ryanjbaxter/git-repos/spring-cloud/scripts/docs/../src/test/resources/contracts</directory>
<outputDirectory>META-INF/${project.groupId}/${project.artifactId}/${project.version}/contracts</outputDirectory>
<includes>
<include>**/*.groovy</include>
</includes>
</fileSet>
</fileSets>
</assembly>
ext {
contractsDir = file("mappings")
stubsOutputDirRoot = file("${project.buildDir}/production/${project.name}-stubs/")
}
// Automatically added by plugin:
// copyContracts - copies contracts to the output folder from which JAR will be created
// verifierStubsJar - JAR with a provided stub suffix
// the presented publication is also added by the plugin but you can modify it as you wish
publishing {
publications {
stubs(MavenPublication) {
artifactId "${project.name}-stubs"
artifact verifierStubsJar
}
}
}
Stub Runner Core
Runs stubs for service collaborators. Treating stubs as contracts of services allows to use stub-runner as an implementation of Consumer Driven Contracts.
Stub Runner allows you to automatically download the stubs of the provided dependencies, start WireMock servers for them and feed them with proper stub definitions. For messaging, special stub routes are defined.
Running stubs
Limitations
Important
|
There might be a problem with StubRunner shutting down ports between tests. You might
have a situation in which you get port conflicts. As long as you use the same context across tests
everything works fine. But when the context are different (e.g. different stubs or different profiles)
then you have to either use @DirtiesContext to shut down the stub servers, or else run them on
different ports per test.
|
Running using main app
You can set the following options to the main class:
-c, --classifier Suffix for the jar containing stubs (e.
g. 'stubs' if the stub jar would
have a 'stubs' classifier for stubs:
foobar-stubs ). Defaults to 'stubs'
(default: stubs)
--maxPort, --maxp <Integer> Maximum port value to be assigned to
the WireMock instance. Defaults to
15000 (default: 15000)
--minPort, --minp <Integer> Minimum port value to be assigned to
the WireMock instance. Defaults to
10000 (default: 10000)
-p, --password Password to user when connecting to
repository
--phost, --proxyHost Proxy host to use for repository
requests
--pport, --proxyPort [Integer] Proxy port to use for repository
requests
-r, --root Location of a Jar containing server
where you keep your stubs (e.g. http:
//nexus.
net/content/repositories/repository)
-s, --stubs Comma separated list of Ivy
representation of jars with stubs.
Eg. groupid:artifactid1,groupid2:
artifactid2:classifier
-u, --username Username to user when connecting to
repository
--wo, --workOffline Switch to work offline. Defaults to
'false'
HTTP Stubs
Stubs are defined in JSON documents, whose syntax is defined in WireMock documentation
Example:
{
"request": {
"method": "GET",
"url": "/ping"
},
"response": {
"status": 200,
"body": "pong",
"headers": {
"Content-Type": "text/plain"
}
}
}
Viewing registered mappings
Every stubbed collaborator exposes list of defined mappings under __/admin/
endpoint.
Messaging Stubs
Depending on the provided Stub Runner dependency and the DSL the messaging routes are automatically set up.
Stub Runner JUnit Rule
Stub Runner comes with a JUnit rule thanks to which you can very easily download and run stubs for given group and artifact id:
@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
.repoRoot(repoRoot())
.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer");
After that rule gets executed Stub Runner connects to your Maven repository and for the given list of dependencies tries to:
-
download them
-
cache them locally
-
unzip them to a temporary folder
-
start a WireMock server for each Maven dependency on a random port from the provided range of ports / provided port
-
feed the WireMock server with all JSON files that are valid WireMock definitions
-
can also send messages (remember to pass an implementation of
MessageVerifier
interface)
Stub Runner uses Eclipse Aether mechanism to download the Maven dependencies. Check their docs for more information.
Since the StubRunnerRule
implements the StubFinder
it allows you to find the started stubs:
/*
* Copyright 2013-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.cloud.contract.stubrunner;
import java.net.URL;
import java.util.Collection;
import java.util.Map;
import org.springframework.cloud.contract.spec.Contract;
public interface StubFinder extends StubTrigger {
/**
* For the given groupId and artifactId tries to find the matching
* URL of the running stub.
*
* @param groupId - might be null. In that case a search only via artifactId takes place
* @return URL of a running stub or throws exception if not found
*/
URL findStubUrl(String groupId, String artifactId) throws StubNotFoundException;
/**
* For the given Ivy notation {@code [groupId]:artifactId:[version]:[classifier]} tries to
* find the matching URL of the running stub. You can also pass only {@code artifactId}.
*
* @param ivyNotation - Ivy representation of the Maven artifact
* @return URL of a running stub or throws exception if not found
*/
URL findStubUrl(String ivyNotation) throws StubNotFoundException;
/**
* Returns all running stubs
*/
RunningStubs findAllRunningStubs();
/**
* Returns the list of Contracts
*/
Map<StubConfiguration, Collection<Contract>> getContracts();
}
Example of usage in Spock tests:
@ClassRule @Shared StubRunnerRule rule = new StubRunnerRule()
.repoRoot(StubRunnerRuleSpec.getResource("/m2repo/repository").toURI().toString())
.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")
def 'should start WireMock servers'() {
expect: 'WireMocks are running'
rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
rule.findStubUrl('loanIssuance') != null
rule.findStubUrl('loanIssuance') == rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
rule.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
and:
rule.findAllRunningStubs().isPresent('loanIssuance')
rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
rule.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
and: 'Stubs were registered'
"${rule.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
"${rule.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
}
Example of usage in JUnit tests:
@Test
public void should_start_wiremock_servers() throws Exception {
// expect: 'WireMocks are running'
then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")).isNotNull();
then(rule.findStubUrl("loanIssuance")).isNotNull();
then(rule.findStubUrl("loanIssuance")).isEqualTo(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs", "loanIssuance"));
then(rule.findStubUrl("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isNotNull();
// and:
then(rule.findAllRunningStubs().isPresent("loanIssuance")).isTrue();
then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs", "fraudDetectionServer")).isTrue();
then(rule.findAllRunningStubs().isPresent("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer")).isTrue();
// and: 'Stubs were registered'
then(httpGet(rule.findStubUrl("loanIssuance").toString() + "/name")).isEqualTo("loanIssuance");
then(httpGet(rule.findStubUrl("fraudDetectionServer").toString() + "/name")).isEqualTo("fraudDetectionServer");
}
Check the Common properties for JUnit and Spring for more information on how to apply global configuration of Stub Runner.
Important
|
To use the JUnit rule together with messaging you have to provide an implementation of the
MessageVerifier interface to the rule builder (e.g. rule.messageVerifier(new MyMessageVerifier()) ).
If you don’t do this then whenever you try to send a message an exception will be thrown.
|
Maven settings
The stub downloader honors Maven settings for a different local repository folder. Authentication details for repositories and profiles are currently not taken into account, so you need to specify it using the properties mentioned above.
Providing fixed ports
You can also run your stubs on fixed ports. You can do it in two different ways. One is to pass it in the properties, and the other via fluent API of JUnit rule.
Fluent API
When using the StubRunnerRule
you can add a stub to download and then pass the port for the last downloaded stub.
@ClassRule public static StubRunnerRule rule = new StubRunnerRule()
.repoRoot(repoRoot())
.downloadStub("org.springframework.cloud.contract.verifier.stubs", "loanIssuance")
.withPort(12345)
.downloadStub("org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer:12346");
You can see that for this example the following test is valid:
then(rule.findStubUrl("loanIssuance")).isEqualTo(URI.create("http://localhost:12345").toURL());
then(rule.findStubUrl("fraudDetectionServer")).isEqualTo(URI.create("http://localhost:12346").toURL());
Stub Runner with Spring
Sets up Spring configuration of the Stub Runner project.
By providing a list of stubs inside your configuration file the Stub Runner automatically downloads and registers in WireMock the selected stubs.
If you want to find the URL of your stubbed dependency you can autowire the StubFinder
interface and use
its methods as presented below:
@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
@SpringBootTest(properties = [" stubrunner.cloud.enabled=false",
"stubrunner.camel.enabled=false",
'foo=${stubrunner.runningstubs.fraudDetectionServer.port}'])
@AutoConfigureStubRunner
@DirtiesContext
@ActiveProfiles("test")
class StubRunnerConfigurationSpec extends Specification {
@Autowired StubFinder stubFinder
@Autowired Environment environment
@Value('${foo}') Integer foo
@BeforeClass
@AfterClass
void setupProps() {
System.clearProperty("stubrunner.repository.root")
System.clearProperty("stubrunner.classifier")
}
def 'should start WireMock servers'() {
expect: 'WireMocks are running'
stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance') != null
stubFinder.findStubUrl('loanIssuance') != null
stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs', 'loanIssuance')
stubFinder.findStubUrl('loanIssuance') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance')
stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT') == stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs')
stubFinder.findStubUrl('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer') != null
and:
stubFinder.findAllRunningStubs().isPresent('loanIssuance')
stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs', 'fraudDetectionServer')
stubFinder.findAllRunningStubs().isPresent('org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer')
and: 'Stubs were registered'
"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
}
def 'should throw an exception when stub is not found'() {
when:
stubFinder.findStubUrl('nonExistingService')
then:
thrown(StubNotFoundException)
when:
stubFinder.findStubUrl('nonExistingGroupId', 'nonExistingArtifactId')
then:
thrown(StubNotFoundException)
}
def 'should register started servers as environment variables'() {
expect:
environment.getProperty("stubrunner.runningstubs.loanIssuance.port") != null
stubFinder.findAllRunningStubs().getPort("loanIssuance") == (environment.getProperty("stubrunner.runningstubs.loanIssuance.port") as Integer)
and:
environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") != null
stubFinder.findAllRunningStubs().getPort("fraudDetectionServer") == (environment.getProperty("stubrunner.runningstubs.fraudDetectionServer.port") as Integer)
}
def 'should be able to interpolate a running stub in the passed test property'() {
given:
int fraudPort = stubFinder.findAllRunningStubs().getPort("fraudDetectionServer")
expect:
fraudPort > 0
environment.getProperty("foo", Integer) == fraudPort
foo == fraudPort
}
@Configuration
@EnableAutoConfiguration
static class Config {}
}
for the following configuration file:
stubrunner:
repositoryRoot: classpath:m2repo/repository/
ids:
- org.springframework.cloud.contract.verifier.stubs:loanIssuance
- org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer
- org.springframework.cloud.contract.verifier.stubs:bootService
Instead of using the properties you can also use the properties inside the @AutoConfigureStubRunner
.
Below you can find an example of achieving the same result by setting values on the annotation.
@AutoConfigureStubRunner(
ids = ["org.springframework.cloud.contract.verifier.stubs:loanIssuance",
"org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer",
"org.springframework.cloud.contract.verifier.stubs:bootService"],
repositoryRoot = "classpath:m2repo/repository/")
Stub Runner Spring registers environment variables in the following manner
for every registered WireMock server. Example for Stub Runner ids
com.example:foo
, com.example:bar
.
-
stubrunner.runningstubs.foo.port
-
stubrunner.runningstubs.bar.port
Which you can reference in your code.
Stub Runner Spring Cloud
Stub Runner can integrate with Spring Cloud.
For real life examples you can check the
Stubbing Service Discovery
The most important feature of Stub Runner Spring Cloud
is the fact that it’s stubbing
-
DiscoveryClient
-
Ribbon
ServerList
that means that regardless of the fact whether you’re using Zookeeper, Consul, Eureka or anything else, you don’t need that in your tests.
We’re starting WireMock instances of your dependencies and we’re telling your application whenever you’re using Feign
, load balanced RestTemplate
or DiscoveryClient
directly, to call those stubbed servers instead of calling the real Service Discovery tool.
For example this test will pass
def 'should make service discovery work'() {
expect: 'WireMocks are running'
"${stubFinder.findStubUrl('loanIssuance').toString()}/name".toURL().text == 'loanIssuance'
"${stubFinder.findStubUrl('fraudDetectionServer').toString()}/name".toURL().text == 'fraudDetectionServer'
and: 'Stubs can be reached via load service discovery'
restTemplate.getForObject('http://loanIssuance/name', String) == 'loanIssuance'
restTemplate.getForObject('http://someNameThatShouldMapFraudDetectionServer/name', String) == 'fraudDetectionServer'
}
for the following configuration file
spring.cloud:
zookeeper.enabled: false
consul.enabled: false
eureka.client.enabled: false
stubrunner:
camel.enabled: false
idsToServiceIds:
ivyNotation: someValueInsideYourCode
fraudDetectionServer: someNameThatShouldMapFraudDetectionServer
Test profiles and service discovery
In your integration tests you typically don’t want to call neither a discovery service (e.g. Eureka) or Config Server. That’s why you create an additional test configuration in which you want to disable these features.
Due to certain limitations of spring-cloud-commons
to achieve this you have disable these properties
via a static block like presented below (example for Eureka)
//Hack to work around https://github.com/spring-cloud/spring-cloud-commons/issues/156
static {
System.setProperty("eureka.client.enabled", "false");
System.setProperty("spring.cloud.config.failFast", "false");
}
Additional Configuration
You can match the artifactId of the stub with the name of your app by using the stubrunner.idsToServiceIds:
map.
You can disable Stub Runner Ribbon support by providing: stubrunner.cloud.ribbon.enabled
equal to false
You can disable Stub Runner support by providing: stubrunner.cloud.enabled
equal to false
Tip
|
By default all service discovery will be stubbed. That means that regardless of the fact if you have
an existing DiscoveryClient its results will be ignored. However, if you want to reuse it, just set
stubrunner.cloud.delegate.enabled to true and then your existing DiscoveryClient results will be
merged with the stubbed ones.
|
Stub Runner Boot Application
Spring Cloud Contract Verifier Stub Runner Boot is a Spring Boot application that exposes REST endpoints to trigger the messaging labels and to access started WireMock servers.
One of the use-cases is to run some smoke (end to end) tests on a deployed application. You can read more about this in the "Microservice Deployment" article at Too Much Coding blog.
How to use it?
Just add the
compile "org.springframework.cloud:spring-cloud-starter-stub-runner"
Annotate a class with @EnableStubRunnerServer
, build a fat-jar and you’re ready to go!
For the properties check the Stub Runner Spring section.
Endpoints
HTTP
-
GET
/stubs
- returns a list of all running stubs inivy:integer
notation -
GET
/stubs/{ivy}
- returns a port for the givenivy
notation (when calling the endpointivy
can also beartifactId
only)
Messaging
For Messaging
-
GET
/triggers
- returns a list of all running labels inivy : [ label1, label2 …]
notation -
POST
/triggers/{label}
- executes a trigger withlabel
-
POST
/triggers/{ivy}/{label}
- executes a trigger withlabel
for the givenivy
notation (when calling the endpointivy
can also beartifactId
only)
Example
@ContextConfiguration(classes = StubRunnerBoot, loader = SpringBootContextLoader)
@SpringBootTest(properties = "spring.cloud.zookeeper.enabled=false")
@ActiveProfiles("test")
class StubRunnerBootSpec extends Specification {
@Autowired StubRunning stubRunning
def setup() {
RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning),
new TriggerController(stubRunning))
}
def 'should return a list of running stub servers in "full ivy:port" notation'() {
when:
String response = RestAssuredMockMvc.get('/stubs').body.asString()
then:
def root = new JsonSlurper().parseText(response)
root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs' instanceof Integer
}
def 'should return a port on which a [#stubId] stub is running'() {
when:
def response = RestAssuredMockMvc.get("/stubs/${stubId}")
then:
response.statusCode == 200
response.body.as(Integer) > 0
where:
stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:+:stubs',
'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs',
'org.springframework.cloud.contract.verifier.stubs:bootService:+',
'org.springframework.cloud.contract.verifier.stubs:bootService',
'bootService']
}
def 'should return 404 when missing stub was called'() {
when:
def response = RestAssuredMockMvc.get("/stubs/a:b:c:d")
then:
response.statusCode == 404
}
def 'should return a list of messaging labels that can be triggered when version and classifier are passed'() {
when:
String response = RestAssuredMockMvc.get('/triggers').body.asString()
then:
def root = new JsonSlurper().parseText(response)
root.'org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs'?.containsAll(["delete_book","return_book_1","return_book_2"])
}
def 'should trigger a messaging label'() {
given:
StubRunning stubRunning = Mock()
RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
when:
def response = RestAssuredMockMvc.post("/triggers/delete_book")
then:
response.statusCode == 200
and:
1 * stubRunning.trigger('delete_book')
}
def 'should trigger a messaging label for a stub with [#stubId] ivy notation'() {
given:
StubRunning stubRunning = Mock()
RestAssuredMockMvc.standaloneSetup(new HttpStubsController(stubRunning), new TriggerController(stubRunning))
when:
def response = RestAssuredMockMvc.post("/triggers/$stubId/delete_book")
then:
response.statusCode == 200
and:
1 * stubRunning.trigger(stubId, 'delete_book')
where:
stubId << ['org.springframework.cloud.contract.verifier.stubs:bootService:stubs', 'org.springframework.cloud.contract.verifier.stubs:bootService', 'bootService']
}
def 'should throw exception when trigger is missing'() {
when:
RestAssuredMockMvc.post("/triggers/missing_label")
then:
Exception e = thrown(Exception)
e.message.contains("Exception occurred while trying to return [missing_label] label.")
e.message.contains("Available labels are")
e.message.contains("org.springframework.cloud.contract.verifier.stubs:loanIssuance:0.0.1-SNAPSHOT:stubs=[]")
e.message.contains("org.springframework.cloud.contract.verifier.stubs:bootService:0.0.1-SNAPSHOT:stubs=")
}
}
Stub Runner Boot with Service Discovery
One of the possibilities of using Stub Runner Boot is to use it as a feed of stubs for "smoke-tests". What does it mean? Let’s assume that you don’t want to deploy 50 microservice to a test environment in order to check if your application is working fine. You’ve already executed a suite of tests during the build process but you would also like to ensure that the packaging of your application is fine. What you can do is to deploy your application to an environment, start it and run a couple of tests on it to see if it’s working fine. We can call those tests smoke-tests since their idea is to check only a handful of testing scenarios.
The problem with this approach is such that if you’re doing microservices most likely you’re using a service discovery tool. Stub Runner Boot allows you to solve this issue by starting the required stubs and register them in a service discovery tool. Let’s take a look at an example of such a setup with Eureka. Let’s assume that Eureka was already running.
@SpringBootApplication
@EnableStubRunnerServer
@EnableEurekaClient
@AutoConfigureStubRunner
public class StubRunnerBootEurekaExample {
public static void main(String[] args) {
SpringApplication.run(StubRunnerBootEurekaExample.class, args);
}
}
As you can see we want to start a Stub Runner Boot server @EnableStubRunnerServer
, enable Eureka client @EnableEurekaClient
and we want to have the stub runner feature turned on @AutoConfigureStubRunner
.
Now let’s assume that we want to start this application so that the stubs get automatically registered.
We can do it by running the app java -jar ${SYSTEM_PROPS} stub-runner-boot-eureka-example.jar
where
${SYSTEM_PROPS}
would contain the following list of properties
-Dstubrunner.repositoryRoot=http://repo.spring.io/snapshots (1)
-Dstubrunner.cloud.stubbed.discovery.enabled=false (2)
-Dstubrunner.ids=org.springframework.cloud.contract.verifier.stubs:loanIssuance,org.springframework.cloud.contract.verifier.stubs:fraudDetectionServer,org.springframework.cloud.contract.verifier.stubs:bootService (3)
-Dstubrunner.idsToServiceIds.fraudDetectionServer=someNameThatShouldMapFraudDetectionServer (4)
(1) - we tell Stub Runner where all the stubs reside
(2) - we don't want the default behaviour where the discovery service is stubbed. That's why the stub registration will be picked
(3) - we provide a list of stubs to download
(4) - we provide a list of artifactId to serviceId mapping
That way your deployed application can send requests to started WireMock servers via the service
discovery. Most likely points 1-3 could be set by default in application.yml
cause they are not
likely to change. That way you can provide only the list of stubs to download whenever you start
the Stub Runner Boot.
Stubs Per Consumer
There are cases in which 2 consumers of the same endpoint want to have 2 different responses.
Tip
|
This approach also allows you to immediately know which consumer is using which part of your API. You can remove part of a response that your API produces and you can see which of your autogenerated tests fails. If none fails then you can safely delete that part of the response cause nobody is using it. |
Let’s look at the following example for contract defined for the producer called producer
.
There are 2 consumers: foo-consumer
and bar-consumer
.
Consumer foo-service
request {
url '/foo'
method GET()
}
response {
status 200
body(
foo: "foo"
}
}
Consumer bar-service
request {
url '/foo'
method GET()
}
response {
status 200
body(
bar: "bar"
}
}
You can’t produce for the same request 2 different responses. That’s why you can properly package the
contracts and then profit from the stubsPerConsumer
feature.
On the producer side the consumers can have a folder that contains contracts related only to them.
By setting the stubrunner.stubs-per-consumer
flag to true
we no longer register all stubs but only those that
correspond to the consumer application’s name. In other words we’ll scan the path of every stub and
if it contains the subfolder with name of the consumer in the path only then will it get registered.
On the foo
producer side the contracts would look like this
.
└── contracts
├── bar-consumer
│  ├── bookReturnedForBar.groovy
│  └── shouldCallBar.groovy
└── foo-consumer
├── bookReturnedForFoo.groovy
└── shouldCallFoo.groovy
Being the bar-consumer
consumer you can either set the spring.application.name
or the stubrunner.consumer-name
to bar-consumer
Or set the test as follows:
@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
@SpringBootTest(properties = ["spring.application.name=bar-consumer"])
@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
repositoryRoot = "classpath:m2repo/repository/",
stubsPerConsumer = true)
@DirtiesContext
class StubRunnerStubsPerConsumerSpec extends Specification {
...
}
Then only the stubs registered under a path that contains the bar-consumer
in its name (i.e. those from the
src/test/resources/contracts/bar-consumer/some/contracts/…
folder) will be allowed to be referenced.
Or set the consumer name explicitly
@ContextConfiguration(classes = Config, loader = SpringBootContextLoader)
@SpringBootTest
@AutoConfigureStubRunner(ids = "org.springframework.cloud.contract.verifier.stubs:producerWithMultipleConsumers",
repositoryRoot = "classpath:m2repo/repository/",
consumerName = "foo-consumer",
stubsPerConsumer = true)
@DirtiesContext
class StubRunnerStubsPerConsumerWithConsumerNameSpec extends Specification {
...
}
Then only the stubs registered under a path that contains the foo-consumer
in its name (i.e. those from the
src/test/resources/contracts/foo-consumer/some/contracts/…
folder) will be allowed to be referenced.
You can check out issue 224 for more information about the reasons behind this change.
Common
Common properties for JUnit and Spring
Some of the properties that are repetitive can be set using system properties or configuration properties (for Spring). Here are their names with their default values:
Property name | Default value | Description |
---|---|---|
stubrunner.minPort |
10000 |
Minimal value of a port for a started WireMock with stubs |
stubrunner.maxPort |
15000 |
Minimal value of a port for a started WireMock with stubs |
stubrunner.repositoryRoot |
Maven repo url. If blank then will call the local maven repo |
|
stubrunner.classifier |
stubs |
Default classifier for the stub artifacts |
stubrunner.workOffline |
false |
If true then will not contact any remote repositories to download stubs |
stubrunner.ids |
Array of Ivy notation stubs to download |
|
stubrunner.username |
Optional username to access the tool that stores the JARs with stubs |
|
stubrunner.password |
Optional password to access the tool that stores the JARs with stubs |
|
stubrunner.stubsPerConsumer |
false |
Set to |
stubrunner.consumerName |
If you want to use stubs per consumer and want to override the consumer name just change this value |
Stub runner stubs ids
You can provide the stubs to download via the stubrunner.ids
system property. They follow the following pattern:
groupId:artifactId:version:classifier:port
version
, classifier
and port
are optional.
-
If you don’t provide the
port
then a random one will be picked -
If you don’t provide the
classifier
then the default one will be taken. (NOTE that you can pass an empty classifier like thisgroupId:artifactId:version:
) -
If you don’t provide the
version
then the+
will be passed and the latest one will be downloaded
Where port
means the port of the WireMock server.
Important
|
Starting from version 1.0.4 as a version you can provide a range of versions that you would like the Stub Runner to take into consideration. You can read more about the Aether versioning ranges here. |
Taken from Aether Docs:
This scheme accepts versions of any form, interpreting a version as a sequence of numeric and alphabetic segments. The characters '-', '_', and '.' as well as the mere transitions from digit to letter and vice versa delimit the version segments. Delimiters are treated as equivalent.
Numeric segments are compared mathematically, alphabetic segments are compared lexicographically and case-insensitively. However, the following qualifier strings are recognized and treated specially: "alpha" = "a" < "beta" = "b" < "milestone" = "m" < "cr" = "rc" < "snapshot" < "final" = "ga" < "sp". All of those well-known qualifiers are considered smaller/older than other strings. An empty segment/string is equivalent to 0.
In addition to the above mentioned qualifiers, the tokens "min" and "max" may be used as final version segment to denote the smallest/greatest version having a given prefix. For example, "1.2.min" denotes the smallest version in the 1.2 line, "1.2.max" denotes the greatest version in the 1.2 line. A version range of the form "[M.N.*]" is short for "[M.N.min, M.N.max]".
Numbers and strings are considered incomparable against each other. Where version segments of different kind would collide, comparison will instead assume that the previous segments are padded with trailing 0 or "ga" segments, respectively, until the kind mismatch is resolved, e.g. "1-alpha" = "1.0.0-alpha" < "1.0.1-ga" = "1.0.1".
Stub Runner for Messaging
Stub Runner has the functionality to run the published stubs in memory. It can integrate with the following frameworks out of the box
-
Spring Integration
-
Spring Cloud Stream
-
Apache Camel
-
Spring AMQP
It also provides points of entry to integrate with any other solution on the market.
Stub triggering
To trigger a message it’s enough to use the StubTrigger
interface:
/*
* Copyright 2013-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.cloud.contract.stubrunner;
import java.util.Collection;
import java.util.Map;
public interface StubTrigger {
/**
* Triggers an event by a given label for a given {@code groupid:artifactid} notation. You can use only {@code artifactId} too.
*
* Feature related to messaging.
*
* @return true - if managed to run a trigger
*/
boolean trigger(String ivyNotation, String labelName);
/**
* Triggers an event by a given label.
*
* Feature related to messaging.
*
* @return true - if managed to run a trigger
*/
boolean trigger(String labelName);
/**
* Triggers all possible events.
*
* Feature related to messaging.
*
* @return true - if managed to run a trigger
*/
boolean trigger();
/**
* Returns a mapping of ivy notation of a dependency to all the labels it has.
*
* Feature related to messaging.
*/
Map<String, Collection<String>> labels();
}
For convenience the StubFinder
interface extends StubTrigger
so it’s enough to use only one in your tests.
StubTrigger
gives you the following options to trigger a message:
Trigger by label
stubFinder.trigger('return_book_1')
Trigger by group and artifact ids
stubFinder.trigger('org.springframework.cloud.contract.verifier.stubs:camelService', 'return_book_1')
Trigger by artifact ids
stubFinder.trigger('camelService', 'return_book_1')
Trigger all messages
stubFinder.trigger()
Stub Runner Camel
Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to integrate with Apache Camel. For the provided artifacts it will automatically download the stubs and register the required routes.
Adding it to the project
It’s enough to have both Apache Camel and Spring Cloud Contract Stub Runner on classpath.
Remember to annotate your test class with @AutoConfigureStubRunner
.
Examples
Stubs structure
Let us assume that we have the following Maven repository with a deployed stubs for the
camelService
application.
└── .m2
└── repository
└── io
└── codearte
└── accurest
└── stubs
└── camelService
├── 0.0.1-SNAPSHOT
│  ├── camelService-0.0.1-SNAPSHOT.pom
│  ├── camelService-0.0.1-SNAPSHOT-stubs.jar
│  └── maven-metadata-local.xml
└── maven-metadata-local.xml
And the stubs contain the following structure:
├── META-INF
│  └── MANIFEST.MF
└── repository
├── accurest
│  ├── bookDeleted.groovy
│  ├── bookReturned1.groovy
│  └── bookReturned2.groovy
└── mappings
Let’s consider the following contracts (let' number it with 1):
Contract.make {
label 'return_book_1'
input {
triggeredBy('bookReturnedTriggered()')
}
outputMessage {
sentTo('jms:output')
body('''{ "bookName" : "foo" }''')
headers {
header('BOOK-NAME', 'foo')
}
}
}
and number 2
Contract.make {
label 'return_book_2'
input {
messageFrom('jms:input')
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo('jms:output')
body([
bookName: 'foo'
])
headers {
header('BOOK-NAME', 'foo')
}
}
}
Scenario 1 (no input message)
So as to trigger a message via the return_book_1
label we’ll use the StubTigger
interface as follows
stubFinder.trigger('return_book_1')
Next we’ll want to listen to the output of the message sent to jms:output
Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)
And the received message would pass the following assertions
receivedMessage != null
assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
receivedMessage.in.headers.get('BOOK-NAME') == 'foo'
Scenario 2 (output triggered by input)
Since the route is set for you it’s enough to just send a message to the jms:output
destination.
camelContext.createProducerTemplate().sendBodyAndHeaders('jms:input', new BookReturned('foo'), [sample: 'header'])
Next we’ll want to listen to the output of the message sent to jms:output
Exchange receivedMessage = camelContext.createConsumerTemplate().receive('jms:output', 5000)
And the received message would pass the following assertions
receivedMessage != null
assertThatBodyContainsBookNameFoo(receivedMessage.in.body)
receivedMessage.in.headers.get('BOOK-NAME') == 'foo'
Scenario 3 (input with no output)
Since the route is set for you it’s enough to just send a message to the jms:output
destination.
camelContext.createProducerTemplate().sendBodyAndHeaders('jms:delete', new BookReturned('foo'), [sample: 'header'])
Stub Runner Integration
Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to integrate with Spring Integration. For the provided artifacts it will automatically download the stubs and register the required routes.
Adding it to the project
It’s enough to have both Spring Integration and Spring Cloud Contract Stub Runner on classpath.
Remember to annotate your test class with @AutoConfigureStubRunner
.
Examples
Stubs structure
Let us assume that we have the following Maven repository with a deployed stubs for the
integrationService
application.
└── .m2
└── repository
└── io
└── codearte
└── accurest
└── stubs
└── integrationService
├── 0.0.1-SNAPSHOT
│  ├── integrationService-0.0.1-SNAPSHOT.pom
│  ├── integrationService-0.0.1-SNAPSHOT-stubs.jar
│  └── maven-metadata-local.xml
└── maven-metadata-local.xml
And the stubs contain the following structure:
├── META-INF
│  └── MANIFEST.MF
└── repository
├── accurest
│  ├── bookDeleted.groovy
│  ├── bookReturned1.groovy
│  └── bookReturned2.groovy
└── mappings
Let’s consider the following contracts (let' number it with 1):
Contract.make {
label 'return_book_1'
input {
triggeredBy('bookReturnedTriggered()')
}
outputMessage {
sentTo('output')
body('''{ "bookName" : "foo" }''')
headers {
header('BOOK-NAME', 'foo')
}
}
}
and number 2
Contract.make {
label 'return_book_2'
input {
messageFrom('input')
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo('output')
body([
bookName: 'foo'
])
headers {
header('BOOK-NAME', 'foo')
}
}
}
and the following Spring Integration Route:
<?xml version="1.0" encoding="UTF-8"?>
<!--
~ Copyright 2013-2017 the original author or authors.
~
~ Licensed under the Apache License, Version 2.0 (the "License");
~ you may not use this file except in compliance with the License.
~ You may obtain a copy of the License at
~
~ https://www.apache.org/licenses/LICENSE-2.0
~
~ Unless required by applicable law or agreed to in writing, software
~ distributed under the License is distributed on an "AS IS" BASIS,
~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
~ See the License for the specific language governing permissions and
~ limitations under the License.
-->
<beans:beans xmlns="http://www.springframework.org/schema/integration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:beans="http://www.springframework.org/schema/beans"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/integration
http://www.springframework.org/schema/integration/spring-integration.xsd">
<!-- REQUIRED FOR TESTING -->
<bridge input-channel="output"
output-channel="outputTest"/>
<channel id="outputTest">
<queue/>
</channel>
</beans:beans>
Scenario 1 (no input message)
So as to trigger a message via the return_book_1
label we’ll use the StubTigger
interface as follows
stubFinder.trigger('return_book_1')
Next we’ll want to listen to the output of the message sent to output
Message<?> receivedMessage = messaging.receive('outputTest')
And the received message would pass the following assertions
receivedMessage != null
assertJsons(receivedMessage.payload)
receivedMessage.headers.get('BOOK-NAME') == 'foo'
Scenario 2 (output triggered by input)
Since the route is set for you it’s enough to just send a message to the output
destination.
messaging.send(new BookReturned('foo'), [sample: 'header'], 'input')
Next we’ll want to listen to the output of the message sent to output
Message<?> receivedMessage = messaging.receive('outputTest')
And the received message would pass the following assertions
receivedMessage != null
assertJsons(receivedMessage.payload)
receivedMessage.headers.get('BOOK-NAME') == 'foo'
Scenario 3 (input with no output)
Since the route is set for you it’s enough to just send a message to the input
destination.
messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')
Stub Runner Stream
Spring Cloud Contract Verifier Stub Runner’s messaging module gives you an easy way to integrate with Spring Stream. For the provided artifacts it will automatically download the stubs and register the required routes.
Warning
|
In Stub Runner’s integration with Stream the messageFrom or sentTo Strings are resolved
first as a destination of a channel, and then if there is no such destination it’s resolved as a
channel name.
|
Adding it to the project
It’s enough to have both Spring Cloud Stream and Spring Cloud Contract Stub Runner on classpath.
Remember to annotate your test class with @AutoConfigureStubRunner
.
Examples
Stubs structure
Let us assume that we have the following Maven repository with a deployed stubs for the
streamService
application.
└── .m2
└── repository
└── io
└── codearte
└── accurest
└── stubs
└── streamService
├── 0.0.1-SNAPSHOT
│  ├── streamService-0.0.1-SNAPSHOT.pom
│  ├── streamService-0.0.1-SNAPSHOT-stubs.jar
│  └── maven-metadata-local.xml
└── maven-metadata-local.xml
And the stubs contain the following structure:
├── META-INF
│  └── MANIFEST.MF
└── repository
├── accurest
│  ├── bookDeleted.groovy
│  ├── bookReturned1.groovy
│  └── bookReturned2.groovy
└── mappings
Let’s consider the following contracts (let' number it with 1):
Contract.make {
label 'return_book_1'
input { triggeredBy('bookReturnedTriggered()') }
outputMessage {
sentTo('returnBook')
body('''{ "bookName" : "foo" }''')
headers { header('BOOK-NAME', 'foo') }
}
}
and number 2
Contract.make {
label 'return_book_2'
input {
messageFrom('bookStorage')
messageBody([
bookName: 'foo'
])
messageHeaders { header('sample', 'header') }
}
outputMessage {
sentTo('returnBook')
body([
bookName: 'foo'
])
headers { header('BOOK-NAME', 'foo') }
}
}
and the following Spring configuration:
stubrunner.repositoryRoot: classpath:m2repo/repository/
stubrunner.ids: org.springframework.cloud.contract.verifier.stubs:streamService:0.0.1-SNAPSHOT:stubs
spring:
cloud:
stream:
bindings:
output:
destination: returnBook
input:
destination: bookStorage
server:
port: 0
Scenario 1 (no input message)
So as to trigger a message via the return_book_1
label we’ll use the StubTrigger
interface as follows
stubFinder.trigger('return_book_1')
Next we’ll want to listen to the output of the message sent to a channel whose destination
is returnBook
Message<?> receivedMessage = messaging.receive('returnBook')
And the received message would pass the following assertions
receivedMessage != null
assertJsons(receivedMessage.payload)
receivedMessage.headers.get('BOOK-NAME') == 'foo'
Scenario 2 (output triggered by input)
Since the route is set for you it’s enough to just send a message to the bookStorage
destination
.
messaging.send(new BookReturned('foo'), [sample: 'header'], 'bookStorage')
Next we’ll want to listen to the output of the message sent to returnBook
Message<?> receivedMessage = messaging.receive('returnBook')
And the received message would pass the following assertions
receivedMessage != null
assertJsons(receivedMessage.payload)
receivedMessage.headers.get('BOOK-NAME') == 'foo'
Scenario 3 (input with no output)
Since the route is set for you it’s enough to just send a message to the output
destination.
messaging.send(new BookReturned('foo'), [sample: 'header'], 'delete')
Stub Runner Spring AMQP
Spring Cloud Contract Verifier Stub Runner’s messaging module provides an easy way to integrate with Spring AMQP’s Rabbit Template. For the provided artifacts it will automatically download the stubs and register the required routes.
The integration tries to work standalone, that is without interaction with a running RabbitMQ message broker.
It expects a RabbitTemplate
on the application context and uses it as a spring boot test @SpyBean
.
Thus it can use the mockito spy functionality to verify and introspect messages sent by the application.
On the message consumer side, it considers all @RabbitListener
annotated endpoints as well as all `SimpleMessageListenerContainer`s on the application context.
As messages are usually sent to exchanges in AMQP the message contract contains the exchange name as the destination. Message listeners on the other side are bound to queues. Bindings connect an exchange to a queue. If message contracts are triggered the Spring AMQP stub runner integration will look for bindings on the application context that match this exchange. Then it collects the queues from the Spring exchanges and tries to find messages listeners bound to these queues. The message is triggered to all matching message listeners.
Adding it to the project
It’s enough to have both Spring AMQP and Spring Cloud Contract Stub Runner on the classpath and set the property stubrunner.amqp.enabled=true
.
Remember to annotate your test class with @AutoConfigureStubRunner
.
Examples
Stubs structure
Let us assume that we have the following Maven repository with a deployed stubs for the
spring-cloud-contract-amqp-test
application.
└── .m2
└── repository
└── com
└── example
└── spring-cloud-contract-amqp-test
├── 0.4.0-SNAPSHOT
│  ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT.pom
│  ├── spring-cloud-contract-amqp-test-0.4.0-SNAPSHOT-stubs.jar
│  └── maven-metadata-local.xml
└── maven-metadata-local.xml
And the stubs contain the following structure:
├── META-INF
│  └── MANIFEST.MF
└── contracts
└── shouldProduceValidPersonData.groovy
Let’s consider the following contract:
Contract.make {
// Human readable description
description 'Should produce valid person data'
// Label by means of which the output message can be triggered
label 'contract-test.person.created.event'
// input to the contract
input {
// the contract will be triggered by a method
triggeredBy('createPerson()')
}
// output message of the contract
outputMessage {
// destination to which the output message will be sent
sentTo 'contract-test.exchange'
headers {
header('contentType': 'application/json')
header('__TypeId__': 'org.springframework.cloud.contract.stubrunner.messaging.amqp.Person')
}
// the body of the output message
body ([
id: $(consumer(9), producer(regex("[0-9]+"))),
name: "me"
])
}
}
and the following Spring configuration:
stubrunner:
repositoryRoot: classpath:m2repo/repository/
ids: org.springframework.cloud.contract.verifier.stubs.amqp:spring-cloud-contract-amqp-test:0.4.0-SNAPSHOT:stubs
amqp:
enabled: true
server:
port: 0
Triggering the message
So to trigger a message using the contract above we’ll use the StubTrigger
interface as follows.
stubTrigger.trigger("contract-test.person.created.event")
The message has the destination contract-test.exchange
so the Spring AMQP stub runner integration looks for bindings related to this exchange.
@Bean
public Binding binding() {
return BindingBuilder.bind(new Queue("test.queue")).to(new DirectExchange("contract-test.exchange")).with("#");
}
The binding definition binds the queue test.queue
.
So the following listener definition is a match and is invoked with the contract message.
@Bean
public SimpleMessageListenerContainer simpleMessageListenerContainer(ConnectionFactory connectionFactory,
MessageListenerAdapter listenerAdapter) {
SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
container.setConnectionFactory(connectionFactory);
container.setQueueNames("test.queue");
container.setMessageListener(listenerAdapter);
return container;
}
Also, the following annotated listener represents a match and would be invoked.
@RabbitListener(bindings = @QueueBinding(
value = @Queue(value = "test.queue"),
exchange = @Exchange(value = "contract-test.exchange", ignoreDeclarationExceptions = "true")))
public void handlePerson(Person person) {
this.person = person;
}
Note
|
The message is directly handed over to the onMessage method of the MessageListener associated with the matching SimpleMessageListenerContainer .
|
Spring AMQP Test Configuration
In order to avoid that Spring AMQP is trying to connect to a running broker during our tests we configure a mock ConnectionFactory
.
To disable the mocked ConnectionFactory set the property stubrunner.amqp.mockConnection=false
stubrunner:
amqp:
mockConnection: false
Contract DSL
Important
|
Remember that inside the contract file you have to provide the fully qualified name to
the Contract class and the make static import i.e. org.springframework.cloud.spec.Contract.make { … } .
You can also provide an import to the Contract class import org.springframework.cloud.spec.Contract and then call
Contract.make { … }
|
Contract DSL is written in Groovy, but don’t be alarmed if you didn’t use Groovy before. Knowledge of the language is not really needed as our DSL uses only a tiny subset of it (namely literals, method calls and closures). What’s more the DSL is designed to be programmer-readable without any knowledge of the DSL itself - it’s statically typed.
The Contract is present in the spring-cloud-contract-spec
module of the Spring Cloud Contract Verifier repository.
Let’s look at full example of a contract definition.
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'PUT'
url '/api/12'
headers {
header 'Content-Type': 'application/vnd.org.springframework.cloud.contract.verifier.twitter-places-analyzer.v1+json'
}
body '''\
[{
"created_at": "Sat Jul 26 09:38:57 +0000 2014",
"id": 492967299297845248,
"id_str": "492967299297845248",
"text": "Gonna see you at Warsaw",
"place":
{
"attributes":{},
"bounding_box":
{
"coordinates":
[[
[-77.119759,38.791645],
[-76.909393,38.791645],
[-76.909393,38.995548],
[-77.119759,38.995548]
]],
"type":"Polygon"
},
"country":"United States",
"country_code":"US",
"full_name":"Washington, DC",
"id":"01fbe706f872cb32",
"name":"Washington",
"place_type":"city",
"url": "http://api.twitter.com/1/geo/id/01fbe706f872cb32.json"
}
}]
'''
}
response {
status 200
}
}
Not all features of the DSL are used in example above. If you didn’t find what you are looking for, please check next paragraphs on this page.
You can easily compile Contracts to WireMock stubs mapping using standalone maven command:
mvn org.springframework.cloud:spring-cloud-contract-maven-plugin:convert
.
Limitations
Warning
|
Spring Cloud Contract Verifier doesn’t support XML properly. Please use JSON or help us implement this feature. |
Warning
|
Spring Cloud Contract Verifier supports equality check on text response. Regular expressions are not yet available. |
Warning
|
The support for the verification of size of JSON arrays is experimental. If you want to turn it on please provide
the value of a system property spring.cloud.contract.verifier.assert.size equal to true . By default this feature is set to
false . You can also provide the assertJsonSize property in the plugin configuration.
|
Warning
|
Due to the fact that JSON structure can have any form it’s sometimes impossible to parse it properly when using
the value(consumer(…), producer(…)) notation when using that in GString. That’s why we highly recommend using the
Groovy Map notation.
|
Common Top-Level elements
Description
You can add a description
to your contract that is nothing else but an arbitrary text. Example:
org.springframework.cloud.contract.spec.Contract.make {
description('''
given:
An input
when:
Sth happens
then:
Output
''')
}
Ignoring contracts
If you want to ignore a contract you can either set a value of ignored contracts in the plugin configuration
or just set the ignored
property on the contract itself:
org.springframework.cloud.contract.spec.Contract.make {
ignored()
}
HTTP Top-Level Elements
Following methods can be called in the top-level closure of a contract definition. Request and response are mandatory, priority is optional.
org.springframework.cloud.contract.spec.Contract.make {
// Definition of HTTP request part of the contract
// (this can be a valid request or invalid depending
// on type of contract being specified).
request {
//...
}
// Definition of HTTP response part of the contract
// (a service implementing this contract should respond
// with following response after receiving request
// specified in "request" part above).
response {
//...
}
// Contract priority, which can be used for overriding
// contracts (1 is highest). Priority is optional.
priority 1
}
Request
HTTP protocol requires only method and address to be specified in a request. The same information is mandatory in request definition of the Contract.
org.springframework.cloud.contract.spec.Contract.make {
request {
// HTTP request method (GET/POST/PUT/DELETE).
method 'GET'
// Path component of request URL is specified as follows.
urlPath('/users')
}
response {
//...
}
}
It is possible to specify whole url
instead of just path, but urlPath
is the recommended way as it makes the tests host-independent.
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
// Specifying `url` and `urlPath` in one contract is illegal.
url('http://localhost:8888/users')
}
response {
//...
}
}
Request may contain query parameters, which are specified in a closure nested in a call to urlPath
or url
.
org.springframework.cloud.contract.spec.Contract.make {
request {
//...
urlPath('/users') {
// Each parameter is specified in form
// `'paramName' : paramValue` where parameter value
// may be a simple literal or one of matcher functions,
// all of which are used in this example.
queryParameters {
// If a simple literal is used as value
// default matcher function is used (equalTo)
parameter 'limit': 100
// `equalTo` function simply compares passed value
// using identity operator (==).
parameter 'filter': equalTo("email")
// `containing` function matches strings
// that contains passed substring.
parameter 'gender': value(consumer(containing("[mf]")), producer('mf'))
// `matching` function tests parameter
// against passed regular expression.
parameter 'offset': value(consumer(matching("[0-9]+")), producer(123))
// `notMatching` functions tests if parameter
// does not match passed regular expression.
parameter 'loginStartsWith': value(consumer(notMatching(".{0,2}")), producer(3))
}
}
//...
}
response {
//...
}
}
It may contain additional request headers…
org.springframework.cloud.contract.spec.Contract.make {
request {
//...
// Each header is added in form `'Header-Name' : 'Header-Value'`.
// there are also some helper methods
headers {
header 'key': 'value'
contentType(applicationJson())
}
//...
}
response {
//...
}
}
…and a request body.
org.springframework.cloud.contract.spec.Contract.make {
request {
//...
// Currently only JSON format of request body is supported.
// Format will be determined from a header or body's content.
body '''{ "login" : "john", "name": "John The Contract" }'''
}
response {
//...
}
}
Response
Minimal response must contain HTTP status code.
org.springframework.cloud.contract.spec.Contract.make {
request {
//...
}
response {
// Status code sent by the server
// in response to request specified above.
status 200
}
}
Besides status response may contain headers and body, which are specified the same way as in the request (see previous paragraph).
Dynamic properties
The contract can contain some dynamic properties - timestamps / ids etc. You don’t want to enforce the consumers to stub their
clocks to always return the same value of time so that it gets matched by the stub. That’s why we allow you to provide the dynamic
parts in your contracts in two ways. One is to pass them directly in the
body and one to set them in a separate section called testMatchers
and stubMatchers
.
Dynamic properties inside the body
You can set the properties inside the body either via the value
method
value(consumer(...), producer(...))
value(c(...), p(...))
value(stub(...), test(...))
value(client(...), server(...))
or if you’re using the Groovy map notation for body you can use the $()
method
$(consumer(...), producer(...))
$(c(...), p(...))
$(stub(...), test(...))
$(client(...), server(...))
All of the aforementioned approaches are equal. That means that stub
and client
methods are aliases over the consumer
method. Let’s take a closer look at what we can do with those values in the subsequent sections.
Regular expressions
You can use regular expressions to write your requests in Contract DSL. It is particularly useful when you want to indicate that a given response should be provided for requests that follow a given pattern. Also, you can use it when you need to use patterns and not exact values both for your test and your server side tests.
Please see the example below:
org.springframework.cloud.contract.spec.Contract.make {
request {
method('GET')
url $(consumer(~/\/[0-9]{2}/), producer('/12'))
}
response {
status 200
body(
id: $(anyNumber()),
surname: $(
consumer('Kowalsky'),
producer(regex('[a-zA-Z]+'))
),
name: 'Jan',
created: $(consumer('2014-02-02 12:23:43'), producer(execute('currentDate(it)'))),
correlationId: value(consumer('5d1f9fef-e0dc-4f3d-a7e4-72d2220dd827'),
producer(regex('[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}'))
)
)
headers {
header 'Content-Type': 'text/plain'
}
}
}
You can also provide only one side of the communication using a regular expression. If you do that then automatically we’ll provide the generated string that matches the provided regular expression. For example:
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'PUT'
url value(consumer(regex('/foo/[0-9]{5}')))
body([
requestElement: $(consumer(regex('[0-9]{5}')))
])
headers {
header('header', $(consumer(regex('application\\/vnd\\.fraud\\.v1\\+json;.*'))))
}
}
response {
status 200
body([
responseElement: $(producer(regex('[0-9]{7}')))
])
headers {
contentType("application/vnd.fraud.v1+json")
}
}
}
In this example for request and response the opposite side of the communication will have the respective data generated.
Spring Cloud Contract comes with a series of predefined regular expressions that you can use in your contracts.
protected static final Pattern TRUE_OR_FALSE = Pattern.compile(/(true|false)/)
protected static final Pattern ONLY_ALPHA_UNICODE = Pattern.compile(/[\p{L}]*/)
protected static final Pattern NUMBER = Pattern.compile('-?\\d*(\\.\\d+)?')
protected static final Pattern IP_ADDRESS = Pattern.compile('([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])')
protected static final Pattern HOSTNAME_PATTERN = Pattern.compile('((http[s]?|ftp):/)/?([^:/\\s]+)(:[0-9]{1,5})?')
protected static final Pattern EMAIL = Pattern.compile('[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,4}')
protected static final Pattern URL = UrlHelper.URL
protected static final Pattern UUID = Pattern.compile('[a-z0-9]{8}-[a-z0-9]{4}-[a-z0-9]{4}-[a-z0-9]{4}-[a-z0-9]{12}')
protected static final Pattern ANY_DATE = Pattern.compile('(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])')
protected static final Pattern ANY_DATE_TIME = Pattern.compile('([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
protected static final Pattern ANY_TIME = Pattern.compile('(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])')
protected static final Pattern NON_EMPTY = Pattern.compile(/.+/)
protected static final Pattern NON_BLANK = Pattern.compile(/.*(\S+|\R).*|!^\R*$/)
protected static final Pattern ISO8601_WITH_OFFSET = Pattern.compile(/([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.\d{3})?(Z|[+-][01]\d:[0-5]\d)/)
protected static Pattern anyOf(String... values){
return Pattern.compile(values.collect({"^$it\$"}).join("|"))
}
String onlyAlphaUnicode() {
return ONLY_ALPHA_UNICODE.pattern()
}
String number() {
return NUMBER.pattern()
}
String anyBoolean() {
return TRUE_OR_FALSE.pattern()
}
String ipAddress() {
return IP_ADDRESS.pattern()
}
String hostname() {
return HOSTNAME_PATTERN.pattern()
}
String email() {
return EMAIL.pattern()
}
String url() {
return URL.pattern()
}
String uuid(){
return UUID.pattern()
}
String isoDate() {
return ANY_DATE.pattern()
}
String isoDateTime() {
return ANY_DATE_TIME.pattern()
}
String isoTime() {
return ANY_TIME.pattern()
}
String iso8601WithOffset() {
return ISO8601_WITH_OFFSET.pattern()
}
String nonEmpty() {
return NON_EMPTY.pattern()
}
String nonBlank() {
return NON_BLANK.pattern()
}
so in your contract you can use it like this
Contract dslWithOptionalsInString = Contract.make {
priority 1
request {
method 'POST'
url '/users/password'
headers {
contentType(applicationJson())
}
body(
email: $(consumer(optional(regex(email()))), producer('[email protected]')),
callback_url: $(consumer(regex(hostname())), producer('http://partners.com'))
)
}
response {
status 404
headers {
contentType(applicationJson())
}
body(
code: value(consumer("123123"), producer(optional("123123"))),
message: "User not found by email = [${value(producer(regex(email())), consumer('[email protected]'))}]"
)
}
}
Passing optional parameters
It is possible to provide optional parameters in your contract. It’s only possible to have optional parameter for the:
-
STUB side of the Request
-
TEST side of the Response
Example:
org.springframework.cloud.contract.spec.Contract.make {
priority 1
request {
method 'POST'
url '/users/password'
headers {
contentType(applicationJson())
}
body(
email: $(consumer(optional(regex(email()))), producer('[email protected]')),
callback_url: $(consumer(regex(hostname())), producer('http://partners.com'))
)
}
response {
status 404
headers {
header 'Content-Type': 'application/json'
}
body(
code: value(consumer("123123"), producer(optional("123123")))
)
}
}
By wrapping a part of the body with the optional()
method you are in fact creating a regular expression that should be present 0 or more times.
That way for the example above the following test would be generated if you pick Spock:
"""
given:
def request = given()
.header("Content-Type", "application/json")
.body('''{"email":"[email protected]","callback_url":"http://partners.com"}''')
when:
def response = given().spec(request)
.post("/users/password")
then:
response.statusCode == 404
response.header('Content-Type') == 'application/json'
and:
DocumentContext parsedJson = JsonPath.parse(response.body.asString())
assertThatJson(parsedJson).field("['code']").matches("(123123)?")
"""
and the following stub:
'''
{
"request" : {
"url" : "/users/password",
"method" : "POST",
"bodyPatterns" : [ {
"matchesJsonPath" : "$[?(@.['email'] =~ /([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\\\.[a-zA-Z]{2,4})?/)]"
}, {
"matchesJsonPath" : "$[?(@.['callback_url'] =~ /((http[s]?|ftp):\\\\/)\\\\/?([^:\\\\/\\\\s]+)(:[0-9]{1,5})?/)]"
} ],
"headers" : {
"Content-Type" : {
"equalTo" : "application/json"
}
}
},
"response" : {
"status" : 404,
"body" : "{\\"code\\":\\"123123\\",\\"message\\":\\"User not found by email == [[email protected]]\\"}",
"headers" : {
"Content-Type" : "application/json"
}
},
"priority" : 1
}
'''
Executing custom methods on server side
It is also possible to define a method call to be executed on the server side during the test. Such a method can be added to the class defined as "baseClassForTests" in the configuration. Example:
Contract
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'PUT'
url $(consumer(regex('^/api/[0-9]{2}$')), producer('/api/12'))
headers {
header 'Content-Type': 'application/json'
}
body '''\
[{
"text": "Gonna see you at Warsaw"
}]
'''
}
response {
body (
path: $(consumer('/api/12'), producer(regex('^/api/[0-9]{2}$'))),
correlationId: $(consumer('1223456'), producer(execute('isProperCorrelationId($it)')))
)
status 200
}
}
Base class
abstract class BaseMockMvcSpec extends Specification {
def setup() {
RestAssuredMockMvc.standaloneSetup(new PairIdController())
}
void isProperCorrelationId(Integer correlationId) {
assert correlationId == 123456
}
void isEmpty(String value) {
assert value == null
}
}
Important
|
You can’t use both a String and execute to perform concatenation. E.g. calling
header('Authorization', 'Bearer ' + execute('authToken()')) will lead to improper results.
To make this work just call header('Authorization', execute('authToken()')) and ensure that
the authToken() method returns everything that you need.
|
Dynamic properties in matchers sections
If you’ve been working with Pact this might seem familiar. Quite a few users are used to having a separation between the body and setting dynamic parts of your contract.
That’s why you can profit from two separate sections. One is called stubMatchers
where you can
define the dynamic values that should end up in a stub. You can set it in the request
or inputMessage
part of your contract. The other is called testMatchers
which is present in the response
or
outputMessage
side of the contract.
Currently we support only JSON Path based matchers with the following matching possibilities.
For stubMatchers
:
-
byEquality()
- the value taken from the response via the provided JSON Path needs to be equal to the provided value in the contract -
byRegex(…)
- the value taken from the response via the provided JSON Path needs to match the regex -
byDate()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO Date -
byTimestamp()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO DateTime -
byTime()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO Time
For testMatchers
:
-
byEquality()
- the value taken from the response via the provided JSON Path needs to be equal to the provided value in the contract -
byRegex(…)
- the value taken from the response via the provided JSON Path needs to match the regex -
byDate()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO Date -
byTimestamp()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO DateTime -
byTime()
- the value taken from the response via the provided JSON Path needs to match the regex for ISO Time -
byType()
- the value taken from the response via the provided JSON Path needs to be of the same type as the type defined in the body of the response in the contract.byType
can take a closure where you can setminOccurrence
andmaxOccurrence
. That way you can assert on the size of the collection. -
byCommand(…)
- the value taken from the response via the provided JSON Path will be passed as an input to the custom method that you’re providing. E.g.byCommand('foo($it)')
will result in calling afoo
method to which the value matching the JSON Path will get passed.
Let’s take a look at the following example:
Contract contractDsl = Contract.make {
request {
method 'GET'
urlPath '/get'
body([
duck: 123,
alpha: "abc",
number: 123,
aBoolean: true,
date: "2017-01-01",
dateTime: "2017-01-01T01:23:45",
time: "01:02:34",
valueWithoutAMatcher: "foo",
valueWithTypeMatch: "string",
key: [
'complex.key' : 'foo'
]
])
stubMatchers {
jsonPath('$.duck', byRegex("[0-9]{3}"))
jsonPath('$.duck', byEquality())
jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
jsonPath('$.alpha', byEquality())
jsonPath('$.number', byRegex(number()))
jsonPath('$.aBoolean', byRegex(anyBoolean()))
jsonPath('$.date', byDate())
jsonPath('$.dateTime', byTimestamp())
jsonPath('$.time', byTime())
jsonPath("\$.['key'].['complex.key']", byEquality())
}
headers {
contentType(applicationJson())
}
}
response {
status 200
body([
duck: 123,
alpha: "abc",
number: 123,
aBoolean: true,
date: "2017-01-01",
dateTime: "2017-01-01T01:23:45",
time: "01:02:34",
valueWithoutAMatcher: "foo",
valueWithTypeMatch: "string",
valueWithMin: [
1,2,3
],
valueWithMax: [
1,2,3
],
valueWithMinMax: [
1,2,3
],
valueWithMinEmpty: [],
valueWithMaxEmpty: [],
key: [
'complex.key' : 'foo'
]
])
testMatchers {
// asserts the jsonpath value against manual regex
jsonPath('$.duck', byRegex("[0-9]{3}"))
// asserts the jsonpath value against the provided value
jsonPath('$.duck', byEquality())
// asserts the jsonpath value against some default regex
jsonPath('$.alpha', byRegex(onlyAlphaUnicode()))
jsonPath('$.alpha', byEquality())
jsonPath('$.number', byRegex(number()))
jsonPath('$.aBoolean', byRegex(anyBoolean()))
// asserts vs inbuilt time related regex
jsonPath('$.date', byDate())
jsonPath('$.dateTime', byTimestamp())
jsonPath('$.time', byTime())
// asserts that the resulting type is the same as in response body
jsonPath('$.valueWithTypeMatch', byType())
jsonPath('$.valueWithMin', byType {
// results in verification of size of array (min 1)
minOccurrence(1)
})
jsonPath('$.valueWithMax', byType {
// results in verification of size of array (max 3)
maxOccurrence(3)
})
jsonPath('$.valueWithMinMax', byType {
// results in verification of size of array (min 1 & max 3)
minOccurrence(1)
maxOccurrence(3)
})
jsonPath('$.valueWithMinEmpty', byType {
// results in verification of size of array (min 0)
minOccurrence(0)
})
jsonPath('$.valueWithMaxEmpty', byType {
// results in verification of size of array (max 0)
maxOccurrence(0)
})
// will execute a method `assertThatValueIsANumber`
jsonPath('$.duck', byCommand('assertThatValueIsANumber($it)'))
jsonPath("\$.['key'].['complex.key']", byEquality())
}
headers {
contentType(applicationJson())
}
}
}
In this example we’re providing the dynamic portions of the contract in the matchers sections.
For the request part you can see that for all fields but valueWithoutAMatcher
we’re setting
explicitly the values of regular expressions we’d like the stub to contain. For the valueWithoutAMatcher
the verification will take place in the same way as without the usage of matchers - the test
will perform an equality check in this case.
For the response side in the testMatchers
section we’re defining all the dynamic parts
in a similar manner. The only difference is that we have the byType
matchers too. In that
case we’re checking 4 fields in the way that we’re verifying whether the response from the test
has a value whose JSON path matching the given field is of the same type as the one defined in the response body and:
-
for
$.valueWithTypeMatch
- we’re just checking the whether the type is the same -
for
$.valueWithMin
- we’re checking the type and assert if the size is greater or equal to the min occurrence -
for
$.valueWithMax
- we’re checking the type and assert if the size is smaller or equal to the max occurrence -
for
$.valueWithMinMax
- we’re checking the type and assert if the size is between the min and max occurrence
The resulting test would look more or less like this (note that we’re separating the autogenerated
assertions and the one from matchers with an and
section):
// given:
MockMvcRequestSpecification request = given()
.header("Content-Type", "application/json")
.body("{\"duck\":123,\"alpha\":\"abc\",\"number\":123,\"aBoolean\":true,\"date\":\"2017-01-01\",\"dateTime\":\"2017-01-01T01:23:45\",\"time\":\"01:02:34\",\"valueWithoutAMatcher\":\"foo\",\"valueWithTypeMatch\":\"string\"}");
// when:
ResponseOptions response = given().spec(request)
.get("/get");
// then:
assertThat(response.statusCode()).isEqualTo(200);
assertThat(response.header("Content-Type")).matches("application/json.*");
// and:
DocumentContext parsedJson = JsonPath.parse(response.getBody().asString());
assertThatJson(parsedJson).field("valueWithoutAMatcher").isEqualTo("foo");
// and:
assertThat(parsedJson.read("$.duck", String.class)).matches("[0-9]{3}");
assertThat(parsedJson.read("$.duck", Integer.class)).isEqualTo(123);
assertThat(parsedJson.read("$.alpha", String.class)).matches("[\\p{L}]*");
assertThat(parsedJson.read("$.alpha", String.class)).isEqualTo("abc");
assertThat(parsedJson.read("$.number", String.class)).matches("-?\\d*(\\.\\d+)?");
assertThat(parsedJson.read("$.aBoolean", String.class)).matches("(true|false)");
assertThat(parsedJson.read("$.date", String.class)).matches("(\\d\\d\\d\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])");
assertThat(parsedJson.read("$.dateTime", String.class)).matches("([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
assertThat(parsedJson.read("$.time", String.class)).matches("(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])");
assertThat((Object) parsedJson.read("$.valueWithTypeMatch")).isInstanceOf(java.lang.String.class);
assertThat((Object) parsedJson.read("$.valueWithMin")).isInstanceOf(java.util.List.class);
assertThat(parsedJson.read("$.valueWithMin", java.util.Collection.class).size()).isGreaterThanOrEqualTo(1);
assertThat((Object) parsedJson.read("$.valueWithMax")).isInstanceOf(java.util.List.class);
assertThat(parsedJson.read("$.valueWithMax", java.util.Collection.class).size()).isLessThanOrEqualTo(3);
assertThat((Object) parsedJson.read("$.valueWithMinMax")).isInstanceOf(java.util.List.class);
assertThat(parsedJson.read("$.valueWithMinMax", java.util.Collection.class).size()).isBetween(1, 3);
assertThat((Object) parsedJson.read("$.valueWithMinEmpty")).isInstanceOf(java.util.List.class);
assertThat(parsedJson.read("$.valueWithMinEmpty", java.util.Collection.class).size()).isGreaterThanOrEqualTo(0);
assertThat((Object) parsedJson.read("$.valueWithMaxEmpty")).isInstanceOf(java.util.List.class);
assertThat(parsedJson.read("$.valueWithMaxEmpty", java.util.Collection.class).size()).isLessThanOrEqualTo(0);
assertThatValueIsANumber(parsedJson.read("$.duck"));
and the WireMock stub like this:
'''
{
"request" : {
"urlPath" : "/get",
"method" : "POST",
"headers" : {
"Content-Type" : {
"matches" : "application/json.*"
}
},
"bodyPatterns" : [ {
"matchesJsonPath" : "$[?(@.['valueWithoutAMatcher'] == 'foo')]"
}, {
"matchesJsonPath" : "$[?(@.['valueWithTypeMatch'] == 'string')]"
}, {
"matchesJsonPath" : "$.['list'].['some'].['nested'][?(@.['anothervalue'] == 4)]"
}, {
"matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['anothervalue'] == 4)]"
}, {
"matchesJsonPath" : "$.['list'].['someother'].['nested'][?(@.['json'] == 'with value')]"
}, {
"matchesJsonPath" : "$[?(@.duck =~ /([0-9]{3})/)]"
}, {
"matchesJsonPath" : "$[?(@.duck == 123)]"
}, {
"matchesJsonPath" : "$[?(@.alpha =~ /([\\\\p{L}]*)/)]"
}, {
"matchesJsonPath" : "$[?(@.alpha == 'abc')]"
}, {
"matchesJsonPath" : "$[?(@.number =~ /(-?\\\\d*(\\\\.\\\\d+)?)/)]"
}, {
"matchesJsonPath" : "$[?(@.aBoolean =~ /((true|false))/)]"
}, {
"matchesJsonPath" : "$[?(@.date =~ /((\\\\d\\\\d\\\\d\\\\d)-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01]))/)]"
}, {
"matchesJsonPath" : "$[?(@.dateTime =~ /(([0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
}, {
"matchesJsonPath" : "$[?(@.time =~ /((2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9]))/)]"
}, {
"matchesJsonPath" : "$.list.some.nested[?(@.json =~ /(.*)/)]"
} ]
},
"response" : {
"status" : 200,
"body" : "{\\"duck\\":123,\\"alpha\\":\\"abc\\",\\"number\\":123,\\"aBoolean\\":true,\\"date\\":\\"2017-01-01\\",\\"dateTime\\":\\"2017-01-01T01:23:45\\",\\"time\\":\\"01:02:34\\",\\"valueWithoutAMatcher\\":\\"foo\\",\\"valueWithTypeMatch\\":\\"string\\",\\"valueWithMin\\":[1,2,3],\\"valueWithMax\\":[1,2,3],\\"valueWithMinMax\\":[1,2,3]}",
"headers" : {
"Content-Type" : "application/json"
}
}
}
'''
JAX-RS support
Starting with release 0.8.0 we support JAX-RS 2 Client API. Base class needs to define protected WebTarget webTarget
and server initialization, right now the only option how to test JAX-RS API is to start a web server.
Request with a body needs to have a content type set otherwise application/octet-stream
is going to be used.
In order to use JAX-RS mode, use the following settings:
testMode === 'JAXRSCLIENT'
Example of a test API generated:
'''
// when:
Response response = webTarget
.path("/users")
.queryParam("limit", "10")
.queryParam("offset", "20")
.queryParam("filter", "email")
.queryParam("sort", "name")
.queryParam("search", "55")
.queryParam("age", "99")
.queryParam("name", "Denis.Stepanov")
.queryParam("email", "[email protected]")
.request()
.method("GET");
String responseAsString = response.readEntity(String.class);
// then:
assertThat(response.getStatus()).isEqualTo(200);
// and:
DocumentContext parsedJson = JsonPath.parse(responseAsString);
assertThatJson(parsedJson).field("['property1']").isEqualTo("a");
'''
Async support
If you’re using asynchronous communication on the server side (your controllers are returning
Callable
, DeferredResult
etc. then inside your contract you have to provide in the response
section a async()
method. Example:
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
url '/get'
}
response {
status 200
body 'Passed'
async()
}
}
Working with Context Paths
Spring Cloud Contract supports context paths.
Important
|
The only thing that changes in order to fully support context paths is the switch on the PRODUCER side. The autogenerated tests need to be using the EXPLICIT mode. |
The consumer side remains untouched, in order for the generated test to pass you have to switch the EXPLICIT mode.
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<testMode>EXPLICIT</testMode>
</configuration>
</plugin>
contracts {
testMode = 'EXPLICIT'
}
That way you’ll generate a test that DOES NOT use MockMvc. It means that you’re generating real requests and you need to setup your generated test’s base class to work on a real socket.
Let’s imagine the following contract:
org.springframework.cloud.contract.spec.Contract.make {
request {
method 'GET'
url '/my-context-path/url'
}
response {
status 200
}
}
Here is an example of how to set up a base class and Rest Assured for everything to work correctly.
import com.jayway.restassured.RestAssured;
import org.junit.Before;
import org.springframework.boot.context.embedded.LocalServerPort;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest(classes = ContextPathTestingBaseClass.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
class ContextPathTestingBaseClass {
@LocalServerPort int port;
@Before
public void setup() {
RestAssured.baseURI = "http://localhost";
RestAssured.port = this.port;
}
}
That way all:
-
all your requests in the autogenerated tests will be sent to the real endpoint with your context path included (e.g.
/my-context-path/url
) -
your contracts reflect that you have a context path, thus your generated stubs will also have that information (e.g. in the stubs you’ll see that you have too call
/my-context-path/url
)
Messaging Top-Level Elements
The DSL for messaging looks a little bit different than the one that focuses on HTTP.
Output triggered by a method
The output message can be triggered by calling a method (e.g. a Scheduler was started and a message was sent)
def dsl = Contract.make {
// Human readable description
description 'Some description'
// Label by means of which the output message can be triggered
label 'some_label'
// input to the contract
input {
// the contract will be triggered by a method
triggeredBy('bookReturnedTriggered()')
}
// output message of the contract
outputMessage {
// destination to which the output message will be sent
sentTo('output')
// the body of the output message
body('''{ "bookName" : "foo" }''')
// the headers of the output message
headers {
header('BOOK-NAME', 'foo')
}
}
}
In this case the output message will be sent to output
if a method called bookReturnedTriggered
will be executed. In the message publisher’s side
we will generate a test that will call that method to trigger the message. On the consumer side you can use the some_label
to trigger the message.
Output triggered by a message
The output message can be triggered by receiving a message.
def dsl = Contract.make {
description 'Some Description'
label 'some_label'
// input is a message
input {
// the message was received from this destination
messageFrom('input')
// has the following body
messageBody([
bookName: 'foo'
])
// and the following headers
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo('output')
body([
bookName: 'foo'
])
headers {
header('BOOK-NAME', 'foo')
}
}
}
In this case the output message will be sent to output
if a proper message will be received on the input
destination. In the message publisher’s side
we will generate a test that will send the input message to the defined destination. On the consumer side you can either send a message to the input
destination or use the some_label
to trigger the message.
Consumer / Producer
In HTTP you have a notion of client
/stub and `server
/test
notation. You can use them also in messaging but we’re providing also the consumer
and produer
methods
as presented below (note you can use either $
or value
methods to provide consumer
and producer
parts)
Contract.make {
label 'some_label'
input {
messageFrom value(consumer('jms:output'), producer('jms:input'))
messageBody([
bookName: 'foo'
])
messageHeaders {
header('sample', 'header')
}
}
outputMessage {
sentTo $(consumer('jms:input'), producer('jms:output'))
body([
bookName: 'foo'
])
}
}
Extending the DSL
It is possible to provide your own functions to the DSL. The key requirement for this feature was to maintain the static compatibility. Below you will be able to see an example of:
-
creation of a JAR with reusable classes
-
referencing of these classes in the DSLs
The full example can be found here.
Common JAR
Below you can find three classes that we will reuse in the DSLs.
PatternUtils contains functions used by both the consumer and the producer.
package com.example;
import java.util.regex.Pattern;
/**
* If you want to use {@link Pattern} directly in your tests
* then you can create a class resembling this one. It can
* contain all the {@link Pattern} you want to use in the DSL.
*
* <pre>
* {@code
* request {
* body(
* [ age: $(c(PatternUtils.oldEnough()))]
* )
* }
* </pre>
*
* Notice that we're using both {@code $()} for dynamic values
* and {@code c()} for the consumer side.
*
* @author Marcin Grzejszczak
*/
public class PatternUtils {
public static String tooYoung() {
return "[0-1][0-9]";
}
public static Pattern oldEnough() {
return Pattern.compile("[2-9][0-9]");
}
public static Pattern anyName() {
return Pattern.compile("[a-zA-Z]+");
}
/**
* Makes little sense but it's just an example ;)
*/
public static Pattern ok() {
return Pattern.compile("OK");
}
}
ConsumerUtils contains functions used by the consumer.
package com.example;
import org.springframework.cloud.contract.spec.internal.ClientDslProperty;
import org.springframework.cloud.contract.spec.internal.DslProperty;
/**
* DSL Properties passed to the DSL from the consumer's perspective.
* That means that on the input side {@code Request} for HTTP
* or {@code Input} for messaging you can have a regular expression.
* On the {@code Response} for HTTP or {@code Output} for messaging
* you have to have a concrete value.
*
* @author Marcin Grzejszczak
*/
public class ConsumerUtils {
/**
* Consumer side property. By using the {@link ClientDslProperty}
* you can omit most of boilerplate code from the perspective
* of dynamic values. Example
*
* <pre>
* {@code
* request {
* body(
* [ age: $(ConsumerUtils.oldEnough())]
* )
* }
* </pre>
*
* That way the consumer side value of age field will be
* a regular expression and the producer side will be generated.
*
* @author Marcin Grzejszczak
*/
public static ClientDslProperty oldEnough() {
return new ClientDslProperty(PatternUtils.oldEnough());
}
/**
* Consumer side property. By using the {@link ClientDslProperty}
* you can omit most of boilerplate code from the perspective
* of dynamic values. Example
*
* <pre>
* {@code
* request {
* body(
* [ name: $(ConsumerUtils.anyName())]
* )
* }
* </pre>
*
* That way the consumer will be a regular expression and the
* producer side value will be equal to {@code marcin}
*/
public static DslProperty anyName() {
return new DslProperty<>(PatternUtils.anyName(), "marcin");
}
}
ProducerUtils contains functions used by the producer.
package com.example;
import org.springframework.cloud.contract.spec.internal.ServerDslProperty;
/**
* DSL Properties passed to the DSL from the producer's perspective.
* That means that on the input side {@code Request} for HTTP
* or {@code Input} for messaging you have to have a concrete value.
* On the {@code Response} for HTTP or {@code Output} for messaging
* you can have a regular expression.
*
* @author Marcin Grzejszczak
*/
public class ProducerUtils {
/**
* Producer side property. By using the {@link ProducerUtils}
* you can omit most of boilerplate code from the perspective
* of dynamic values. Example
*
* <pre>
* {@code
* response {
* body(
* [ status: $(ProducerUtils.ok())]
* )
* }
* </pre>
*
* That way the producer side value of age field will be
* a regular expression and the consumer side will be generated.
*/
public static ServerDslProperty ok() {
return new ServerDslProperty(PatternUtils.ok());
}
}
Adding the dependency to project
In order for the plugins and IDE to be able to reference the common JAR classes you need to pass the dependency to your project.
Test dependency in project’s dependencies
First add the common jar dependency as a test dependency. That way since your contracts files are available at test resources path, automatically the common jar classes will be visible in your Groovy files.
<dependency>
<groupId>com.example</groupId>
<artifactId>beer-common</artifactId>
<version>${project.version}</version>
<scope>test</scope>
</dependency>
testCompile("com.example:beer-common:0.0.1-SNAPSHOT")
Test dependency in plugin’s dependencies
Now you have to add the dependency for the plugin to reuse at runtime.
<plugin>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-maven-plugin</artifactId>
<version>${spring-cloud-contract.version}</version>
<extensions>true</extensions>
<configuration>
<packageWithBaseClasses>com.example</packageWithBaseClasses>
</configuration>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-contract-verifier</artifactId>
<version>${spring-cloud-contract.version}</version>
</dependency>
<dependency>
<groupId>com.example</groupId>
<artifactId>beer-common</artifactId>
<version>${project.version}</version>
<scope>compile</scope>
</dependency>
</dependencies>
</plugin>
classpath "com.example:beer-common:0.0.1-SNAPSHOT"
Referencing classes in DSLs
Now you can reference your classes in your DSL. Example:
package contracts.beer.rest
import org.springframework.cloud.contract.spec.Contract
import static com.example.ConsumerUtils.oldEnough
import static com.example.ProducerUtils.ok
Contract.make {
request {
description("""
Represents a successful scenario of getting a beer
given:
client is old enough
when:
he applies for a beer
then:
we'll grant him the beer
""")
method 'POST'
url '/check'
body(
age: $(oldEnough())
)
headers {
contentType(applicationJson())
}
}
response {
status 200
body("""
{
"status": "${value(ok())}"
}
""")
headers {
contentType(applicationJson())
}
}
}
Links
Here you can find interesting links related to Spring Cloud Contract Verifier:
Appendix: Compendium of Configuration Properties
Name | Default | Description |
---|---|---|
encrypt.fail-on-error |
true |
Flag to say that a process should fail if there is an encryption or decryption error. |
encrypt.key |
A symmetric key. As a stronger alternative consider using a keystore. |
|
encrypt.key-store.alias |
Alias for a key in the store. |
|
encrypt.key-store.location |
Location of the key store file, e.g. classpath:/keystore.jks. |
|
encrypt.key-store.password |
Password that locks the keystore. |
|
encrypt.key-store.secret |
Secret protecting the key (defaults to the same as the password). |
|
encrypt.rsa.algorithm |
The RSA algorithm to use (DEFAULT or OEAP). Once it is set do not change it (or existing ciphers will not a decryptable). |
|
encrypt.rsa.salt |
deadbeef |
Salt for the random secret used to encrypt cipher text. Once it is set do not change it (or existing ciphers will not a decryptable). |
encrypt.rsa.strong |
false |
Flag to indicate that "strong" AES encryption should be used internally. If true then the GCM algorithm is applied to the AES encrypted bytes. Default is false (in which case "standard" CBC is used instead). Once it is set do not change it (or existing ciphers will not a decryptable). |
endpoints.bus.enabled |
||
endpoints.bus.id |
||
endpoints.bus.sensitive |
||
endpoints.consul.enabled |
||
endpoints.consul.id |
||
endpoints.consul.sensitive |
||
endpoints.env.post.enabled |
true |
Enable changing the Environment through a POST to /env. |
endpoints.features.enabled |
||
endpoints.features.id |
||
endpoints.features.sensitive |
||
endpoints.pause.enabled |
true |
Enable the /pause endpoint (to send Lifecycle.stop()). |
endpoints.pause.id |
||
endpoints.pause.sensitive |
||
endpoints.refresh.enabled |
true |
Enable the /refresh endpoint to refresh configuration and re-initialize refresh scoped beans. |
endpoints.refresh.id |
||
endpoints.refresh.sensitive |
||
endpoints.restart.enabled |
true |
Enable the /restart endpoint to restart the application context. |
endpoints.restart.id |
||
endpoints.restart.pause-endpoint.enabled |
||
endpoints.restart.pause-endpoint.id |
||
endpoints.restart.pause-endpoint.sensitive |
||
endpoints.restart.resume-endpoint.enabled |
||
endpoints.restart.resume-endpoint.id |
||
endpoints.restart.resume-endpoint.sensitive |
||
endpoints.restart.sensitive |
||
endpoints.restart.timeout |
0 |
|
endpoints.resume.enabled |
true |
Enable the /resume endpoint (to send Lifecycle.start()). |
endpoints.resume.id |
||
endpoints.resume.sensitive |
||
endpoints.zookeeper.enabled |
true |
Enable the /zookeeper endpoint to inspect the state of zookeeper. |
eureka.client.allow-redirects |
false |
Indicates whether server can redirect a client request to a backup server/cluster. If set to false, the server will handle the request directly, If set to true, it may send HTTP redirect to the client, with a new server location. |
eureka.client.availability-zones |
Gets the list of availability zones (used in AWS data centers) for the region in which this instance resides. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds. |
|
eureka.client.backup-registry-impl |
Gets the name of the implementation which implements BackupRegistry to fetch the registry information as a fall back option for only the first time when the eureka client starts. This may be needed for applications which needs additional resiliency for registry information without which it cannot operate. |
|
eureka.client.cache-refresh-executor-exponential-back-off-bound |
10 |
Cache refresh executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred. |
eureka.client.cache-refresh-executor-thread-pool-size |
2 |
The thread pool size for the cacheRefreshExecutor to initialise with |
eureka.client.client-data-accept |
EurekaAccept name for client data accept |
|
eureka.client.decoder-name |
This is a transient config and once the latest codecs are stable, can be removed (as there will only be one) |
|
eureka.client.disable-delta |
false |
Indicates whether the eureka client should disable fetching of delta and should rather resort to getting the full registry information. Note that the delta fetches can reduce the traffic tremendously, because the rate of change with the eureka server is normally much lower than the rate of fetches. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds |
eureka.client.dollar-replacement |
_- |
Get a replacement string for Dollar sign <code>$</code> during serializing/deserializing information in eureka server. |
eureka.client.enabled |
true |
Flag to indicate that the Eureka client is enabled. |
eureka.client.encoder-name |
This is a transient config and once the latest codecs are stable, can be removed (as there will only be one) |
|
eureka.client.escape-char-replacement |
__ |
Get a replacement string for underscore sign <code>_</code> during serializing/deserializing information in eureka server. |
eureka.client.eureka-connection-idle-timeout-seconds |
30 |
Indicates how much time (in seconds) that the HTTP connections to eureka server can stay idle before it can be closed. In the AWS environment, it is recommended that the values is 30 seconds or less, since the firewall cleans up the connection information after a few mins leaving the connection hanging in limbo |
eureka.client.eureka-server-connect-timeout-seconds |
5 |
Indicates how long to wait (in seconds) before a connection to eureka server needs to timeout. Note that the connections in the client are pooled by org.apache.http.client.HttpClient and this setting affects the actual connection creation and also the wait time to get the connection from the pool. |
eureka.client.eureka-server-d-n-s-name |
Gets the DNS name to be queried to get the list of eureka servers.This information is not required if the contract returns the service urls by implementing serviceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. |
|
eureka.client.eureka-server-port |
Gets the port to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS.This information is not required if the contract returns the service urls eurekaServerServiceUrls(String). The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. |
|
eureka.client.eureka-server-read-timeout-seconds |
8 |
Indicates how long to wait (in seconds) before a read from eureka server needs to timeout. |
eureka.client.eureka-server-total-connections |
200 |
Gets the total number of connections that is allowed from eureka client to all eureka servers. |
eureka.client.eureka-server-total-connections-per-host |
50 |
Gets the total number of connections that is allowed from eureka client to a eureka server host. |
eureka.client.eureka-server-u-r-l-context |
Gets the URL context to be used to construct the service url to contact eureka server when the list of eureka servers come from the DNS. This information is not required if the contract returns the service urls from eurekaServerServiceUrls. The DNS mechanism is used when useDnsForFetchingServiceUrls is set to true and the eureka client expects the DNS to configured a certain way so that it can fetch changing eureka servers dynamically. The changes are effective at runtime. |
|
eureka.client.eureka-service-url-poll-interval-seconds |
0 |
Indicates how often(in seconds) to poll for changes to eureka server information. Eureka servers could be added or removed and this setting controls how soon the eureka clients should know about it. |
eureka.client.fetch-registry |
true |
Indicates whether this client should fetch eureka registry information from eureka server. |
eureka.client.fetch-remote-regions-registry |
Comma separated list of regions for which the eureka registry information will be fetched. It is mandatory to define the availability zones for each of these regions as returned by availabilityZones. Failing to do so, will result in failure of discovery client startup. |
|
eureka.client.filter-only-up-instances |
true |
Indicates whether to get the applications after filtering the applications for instances with only InstanceStatus UP states. |
eureka.client.g-zip-content |
true |
Indicates whether the content fetched from eureka server has to be compressed whenever it is supported by the server. The registry information from the eureka server is compressed for optimum network traffic. |
eureka.client.heartbeat-executor-exponential-back-off-bound |
10 |
Heartbeat executor exponential back off related property. It is a maximum multiplier value for retry delay, in case where a sequence of timeouts occurred. |
eureka.client.heartbeat-executor-thread-pool-size |
2 |
The thread pool size for the heartbeatExecutor to initialise with |
eureka.client.initial-instance-info-replication-interval-seconds |
40 |
Indicates how long initially (in seconds) to replicate instance info to the eureka server |
eureka.client.instance-info-replication-interval-seconds |
30 |
Indicates how often(in seconds) to replicate instance changes to be replicated to the eureka server. |
eureka.client.log-delta-diff |
false |
Indicates whether to log differences between the eureka server and the eureka client in terms of registry information. Eureka client tries to retrieve only delta changes from eureka server to minimize network traffic. After receiving the deltas, eureka client reconciles the information from the server to verify it has not missed out some information. Reconciliation failures could happen when the client has had network issues communicating to server.If the reconciliation fails, eureka client gets the full registry information. While getting the full registry information, the eureka client can log the differences between the client and the server and this setting controls that. The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSecondsr |
eureka.client.on-demand-update-status-change |
true |
If set to true, local status updates via ApplicationInfoManager will trigger on-demand (but rate limited) register/updates to remote eureka servers |
eureka.client.prefer-same-zone-eureka |
true |
Indicates whether or not this instance should try to use the eureka server in the same zone for latency and/or other reason. Ideally eureka clients are configured to talk to servers in the same zone The changes are effective at runtime at the next registry fetch cycle as specified by registryFetchIntervalSeconds |
eureka.client.property-resolver |
||
eureka.client.proxy-host |
Gets the proxy host to eureka server if any. |
|
eureka.client.proxy-password |
Gets the proxy password if any. |
|
eureka.client.proxy-port |
Gets the proxy port to eureka server if any. |
|
eureka.client.proxy-user-name |
Gets the proxy user name if any. |
|
eureka.client.region |
us-east-1 |
Gets the region (used in AWS datacenters) where this instance resides. |
eureka.client.register-with-eureka |
true |
Indicates whether or not this instance should register its information with eureka server for discovery by others. In some cases, you do not want your instances to be discovered whereas you just want do discover other instances. |
eureka.client.registry-fetch-interval-seconds |
30 |
Indicates how often(in seconds) to fetch the registry information from the eureka server. |
eureka.client.registry-refresh-single-vip-address |
Indicates whether the client is only interested in the registry information for a single VIP. |
|
eureka.client.service-url |
Map of availability zone to list of fully qualified URLs to communicate with eureka server. Each value can be a single URL or a comma separated list of alternative locations. Typically the eureka server URLs carry protocol,host,port,context and version information if any. Example: http://ec2-256-156-243-129.compute-1.amazonaws.com:7001/eureka/ The changes are effective at runtime at the next service url refresh cycle as specified by eurekaServiceUrlPollIntervalSeconds. |
|
eureka.client.transport |
||
eureka.client.use-dns-for-fetching-service-urls |
false |
Indicates whether the eureka client should use the DNS mechanism to fetch a list of eureka servers to talk to. When the DNS name is updated to have additional servers, that information is used immediately after the eureka client polls for that information as specified in eurekaServiceUrlPollIntervalSeconds. Alternatively, the service urls can be returned serviceUrls, but the users should implement their own mechanism to return the updated list in case of changes. The changes are effective at runtime. |
eureka.dashboard.enabled |
true |
Flag to enable the Eureka dashboard. Default true. |
eureka.dashboard.path |
/ |
The path to the Eureka dashboard (relative to the servlet path). Defaults to "/". |
eureka.instance.a-s-g-name |
Gets the AWS autoscaling group name associated with this instance. This information is specifically used in an AWS environment to automatically put an instance out of service after the instance is launched and it has been disabled for traffic.. |
|
eureka.instance.app-group-name |
Get the name of the application group to be registered with eureka. |
|
eureka.instance.appname |
unknown |
Get the name of the application to be registered with eureka. |
eureka.instance.data-center-info |
Returns the data center this instance is deployed. This information is used to get some AWS specific instance information if the instance is deployed in AWS. |
|
eureka.instance.default-address-resolution-order |
[] |
|
eureka.instance.health-check-url |
Gets the absolute health check page URL for this instance. The users can provide the healthCheckUrlPath if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. |
|
eureka.instance.health-check-url-path |
/health |
Gets the relative health check URL path for this instance. The health check page URL is then constructed out of the hostname and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. |
eureka.instance.home-page-url |
Gets the absolute home page URL for this instance. The users can provide the homePageUrlPath if the home page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to use it as a landing page. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. |
|
eureka.instance.home-page-url-path |
/ |
Gets the relative home page URL Path for this instance. The home page URL is then constructed out of the hostName and the type of communication - secure or unsecure. It is normally used for informational purposes for other services to use it as a landing page. |
eureka.instance.host-info |
||
eureka.instance.hostname |
The hostname if it can be determined at configuration time (otherwise it will be guessed from OS primitives). |
|
eureka.instance.inet-utils |
||
eureka.instance.initial-status |
Initial status to register with rmeote Eureka server. |
|
eureka.instance.instance-enabled-onit |
false |
Indicates whether the instance should be enabled for taking traffic as soon as it is registered with eureka. Sometimes the application might need to do some pre-processing before it is ready to take traffic. |
eureka.instance.instance-id |
Get the unique Id (within the scope of the appName) of this instance to be registered with eureka. |
|
eureka.instance.ip-address |
Get the IPAdress of the instance. This information is for academic purposes only as the communication from other instances primarily happen using the information supplied in {@link #getHostName(boolean)}. |
|
eureka.instance.lease-expiration-duration-in-seconds |
90 |
Indicates the time in seconds that the eureka server waits since it received the last heartbeat before it can remove this instance from its view and there by disallowing traffic to this instance. Setting this value too long could mean that the traffic could be routed to the instance even though the instance is not alive. Setting this value too small could mean, the instance may be taken out of traffic because of temporary network glitches.This value to be set to atleast higher than the value specified in leaseRenewalIntervalInSeconds. |
eureka.instance.lease-renewal-interval-in-seconds |
30 |
Indicates how often (in seconds) the eureka client needs to send heartbeats to eureka server to indicate that it is still alive. If the heartbeats are not received for the period specified in leaseExpirationDurationInSeconds, eureka server will remove the instance from its view, there by disallowing traffic to this instance. Note that the instance could still not take traffic if it implements HealthCheckCallback and then decides to make itself unavailable. |
eureka.instance.metadata-map |
Gets the metadata name/value pairs associated with this instance. This information is sent to eureka server and can be used by other instances. |
|
eureka.instance.namespace |
eureka |
Get the namespace used to find properties. Ignored in Spring Cloud. |
eureka.instance.non-secure-port |
80 |
Get the non-secure port on which the instance should receive traffic. |
eureka.instance.non-secure-port-enabled |
true |
Indicates whether the non-secure port should be enabled for traffic or not. |
eureka.instance.prefer-ip-address |
false |
Flag to say that, when guessing a hostname, the IP address of the server should be used in prference to the hostname reported by the OS. |
eureka.instance.secure-health-check-url |
Gets the absolute secure health check page URL for this instance. The users can provide the secureHealthCheckUrl if the health check page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. <p> It is normally used for making educated decisions based on the health of the instance - for example, it can be used to determine whether to proceed deployments to an entire farm or stop the deployments without causing further damage. The full URL should follow the format http://${eureka.hostname}:7001/ where the value ${eureka.hostname} is replaced at runtime. |
|
eureka.instance.secure-port |
443 |
Get the Secure port on which the instance should receive traffic. |
eureka.instance.secure-port-enabled |
false |
Indicates whether the secure port should be enabled for traffic or not. |
eureka.instance.secure-virtual-host-name |
Gets the secure virtual host name defined for this instance. This is typically the way other instance would find this instance by using the secure virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance. |
|
eureka.instance.status-page-url |
Gets the absolute status page URL path for this instance. The users can provide the statusPageUrlPath if the status page resides in the same instance talking to eureka, else in the cases where the instance is a proxy for some other server, users can provide the full URL. If the full URL is provided it takes precedence. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance. |
|
eureka.instance.status-page-url-path |
/info |
Gets the relative status page URL path for this instance. The status page URL is then constructed out of the hostName and the type of communication - secure or unsecure as specified in securePort and nonSecurePort. It is normally used for informational purposes for other services to find about the status of this instance. Users can provide a simple HTML indicating what is the current status of the instance. |
eureka.instance.virtual-host-name |
Gets the virtual host name defined for this instance. This is typically the way other instance would find this instance by using the virtual host name.Think of this as similar to the fully qualified domain name, that the users of your services will need to find this instance. |
|
eureka.server.a-s-g-cache-expiry-timeout-ms |
0 |
|
eureka.server.a-s-g-query-timeout-ms |
300 |
|
eureka.server.a-s-g-update-interval-ms |
0 |
|
eureka.server.a-w-s-access-id |
||
eureka.server.a-w-s-secret-key |
||
eureka.server.batch-replication |
false |
|
eureka.server.binding-strategy |
||
eureka.server.delta-retention-timer-interval-in-ms |
0 |
|
eureka.server.disable-delta |
false |
|
eureka.server.disable-delta-for-remote-regions |
false |
|
eureka.server.disable-transparent-fallback-to-other-region |
false |
|
eureka.server.e-i-p-bind-rebind-retries |
3 |
|
eureka.server.e-i-p-binding-retry-interval-ms |
0 |
|
eureka.server.e-i-p-binding-retry-interval-ms-when-unbound |
0 |
|
eureka.server.enable-replicated-request-compression |
false |
|
eureka.server.enable-self-preservation |
true |
|
eureka.server.eviction-interval-timer-in-ms |
0 |
|
eureka.server.g-zip-content-from-remote-region |
true |
|
eureka.server.json-codec-name |
||
eureka.server.list-auto-scaling-groups-role-name |
ListAutoScalingGroups |
|
eureka.server.log-identity-headers |
true |
|
eureka.server.max-elements-in-peer-replication-pool |
10000 |
|
eureka.server.max-elements-in-status-replication-pool |
10000 |
|
eureka.server.max-idle-thread-age-in-minutes-for-peer-replication |
15 |
|
eureka.server.max-idle-thread-in-minutes-age-for-status-replication |
10 |
|
eureka.server.max-threads-for-peer-replication |
20 |
|
eureka.server.max-threads-for-status-replication |
1 |
|
eureka.server.max-time-for-replication |
30000 |
|
eureka.server.min-threads-for-peer-replication |
5 |
|
eureka.server.min-threads-for-status-replication |
1 |
|
eureka.server.number-of-replication-retries |
5 |
|
eureka.server.peer-eureka-nodes-update-interval-ms |
0 |
|
eureka.server.peer-eureka-status-refresh-time-interval-ms |
0 |
|
eureka.server.peer-node-connect-timeout-ms |
200 |
|
eureka.server.peer-node-connection-idle-timeout-seconds |
30 |
|
eureka.server.peer-node-read-timeout-ms |
200 |
|
eureka.server.peer-node-total-connections |
1000 |
|
eureka.server.peer-node-total-connections-per-host |
500 |
|
eureka.server.prime-aws-replica-connections |
true |
|
eureka.server.property-resolver |
||
eureka.server.rate-limiter-burst-size |
10 |
|
eureka.server.rate-limiter-enabled |
false |
|
eureka.server.rate-limiter-full-fetch-average-rate |
100 |
|
eureka.server.rate-limiter-privileged-clients |
||
eureka.server.rate-limiter-registry-fetch-average-rate |
500 |
|
eureka.server.rate-limiter-throttle-standard-clients |
false |
|
eureka.server.registry-sync-retries |
0 |
|
eureka.server.registry-sync-retry-wait-ms |
0 |
|
eureka.server.remote-region-app-whitelist |
||
eureka.server.remote-region-connect-timeout-ms |
1000 |
|
eureka.server.remote-region-connection-idle-timeout-seconds |
30 |
|
eureka.server.remote-region-fetch-thread-pool-size |
20 |
|
eureka.server.remote-region-read-timeout-ms |
1000 |
|
eureka.server.remote-region-registry-fetch-interval |
30 |
|
eureka.server.remote-region-total-connections |
1000 |
|
eureka.server.remote-region-total-connections-per-host |
500 |
|
eureka.server.remote-region-trust-store |
||
eureka.server.remote-region-trust-store-password |
changeit |
|
eureka.server.remote-region-urls |
||
eureka.server.remote-region-urls-with-name |
||
eureka.server.renewal-percent-threshold |
0.85 |
|
eureka.server.renewal-threshold-update-interval-ms |
0 |
|
eureka.server.response-cache-auto-expiration-in-seconds |
180 |
|
eureka.server.response-cache-update-interval-ms |
0 |
|
eureka.server.retention-time-in-m-s-in-delta-queue |
0 |
|
eureka.server.route53-bind-rebind-retries |
3 |
|
eureka.server.route53-binding-retry-interval-ms |
0 |
|
eureka.server.route53-domain-t-t-l |
30 |
|
eureka.server.sync-when-timestamp-differs |
true |
|
eureka.server.use-read-only-response-cache |
true |
|
eureka.server.wait-time-in-ms-when-sync-empty |
0 |
|
eureka.server.xml-codec-name |
||
feign.compression.request.mime-types |
[text/xml, application/xml, application/json] |
The list of supported mime types. |
feign.compression.request.min-request-size |
2048 |
The minimum threshold content size. |
health.config.enabled |
false |
Flag to indicate that the config server health indicator should be installed. |
hystrix.metrics.enabled |
true |
Enable Hystrix metrics polling. Defaults to true. |
hystrix.metrics.polling-interval-ms |
2000 |
Interval between subsequent polling of metrics. Defaults to 2000 ms. |
management.health.refresh.enabled |
true |
Enable the health endpoint for the refresh scope. |
management.health.zookeeper.enabled |
true |
Enable the health endpoint for zookeeper. |
netflix.atlas.batch-size |
10000 |
|
netflix.atlas.enabled |
true |
|
netflix.atlas.uri |
||
netflix.metrics.servo.cache-warning-threshold |
1000 |
When the |
netflix.metrics.servo.registry-class |
com.netflix.servo.BasicMonitorRegistry |
Fully qualified class name for monitor registry used by Servo. |
spring.cloud.bus.ack.destination-service |
Service that wants to listen to acks. By default null (meaning all services). |
|
spring.cloud.bus.ack.enabled |
true |
Flag to switch off acks (default on). |
spring.cloud.bus.destination |
springCloudBus |
Name of Spring Cloud Stream destination for messages. |
spring.cloud.bus.enabled |
true |
Flag to indicate that the bus is enabled. |
spring.cloud.bus.env.enabled |
true |
Flag to switch off environment change events (default on). |
spring.cloud.bus.refresh.enabled |
true |
Flag to switch off refresh events (default on). |
spring.cloud.bus.trace.enabled |
false |
Flag to switch on tracing of acks (default off). |
spring.cloud.cloudfoundry.discovery.enabled |
true |
Flag to indicate that discovery is enabled. |
spring.cloud.cloudfoundry.discovery.heartbeat-frequency |
5000 |
Frequency in milliseconds of poll for heart beat. The client will poll on this frequency and broadcast a list of service ids. |
spring.cloud.cloudfoundry.discovery.org |
Organization name to authenticate with (default to user’s default). |
|
spring.cloud.cloudfoundry.discovery.password |
Password for user to authenticate and obtain token. |
|
spring.cloud.cloudfoundry.discovery.space |
Space name to authenticate with (default to user’s default). |
|
spring.cloud.cloudfoundry.discovery.url |
URL of Cloud Foundry API (Cloud Controller). |
|
spring.cloud.cloudfoundry.discovery.username |
Username to authenticate (usually an email address). |
|
spring.cloud.config.allow-override |
true |
Flag to indicate that {@link #isSystemPropertiesOverride() systemPropertiesOverride} can be used. Set to false to prevent users from changing the default accidentally. Default true. |
spring.cloud.config.authorization |
Authorization token used by the client to connect to the server. |
|
spring.cloud.config.discovery.enabled |
false |
Flag to indicate that config server discovery is enabled (config server URL will be looked up via discovery). |
spring.cloud.config.discovery.service-id |
configserver |
Service id to locate config server. |
spring.cloud.config.enabled |
true |
Flag to say that remote configuration is enabled. Default true; |
spring.cloud.config.fail-fast |
false |
Flag to indicate that failure to connect to the server is fatal (default false). |
spring.cloud.config.label |
The label name to use to pull remote configuration properties. The default is set on the server (generally "master" for a git based server). |
|
spring.cloud.config.name |
Name of application used to fetch remote properties. |
|
spring.cloud.config.override-none |
false |
Flag to indicate that when {@link #setAllowOverride(boolean) allowOverride} is true, external properties should take lowest priority, and not override any existing property sources (including local config files). Default false. |
spring.cloud.config.override-system-properties |
true |
Flag to indicate that the external properties should override system properties. Default true. |
spring.cloud.config.password |
The password to use (HTTP Basic) when contacting the remote server. |
|
spring.cloud.config.profile |
default |
The default profile to use when fetching remote configuration (comma-separated). Default is "default". |
spring.cloud.config.retry.initial-interval |
1000 |
Initial retry interval in milliseconds. |
spring.cloud.config.retry.max-attempts |
6 |
Maximum number of attempts. |
spring.cloud.config.retry.max-interval |
2000 |
Maximum interval for backoff. |
spring.cloud.config.retry.multiplier |
1.1 |
Multiplier for next interval. |
spring.cloud.config.token |
Security Token passed thru to underlying environment repository. |
|
spring.cloud.config.uri |
The URI of the remote server (default http://localhost:8888). |
|
spring.cloud.config.username |
The username to use (HTTP Basic) when contacting the remote server. |
|
spring.cloud.consul.config.acl-token |
||
spring.cloud.consul.config.data-key |
data |
If format is Format.PROPERTIES or Format.YAML then the following field is used as key to look up consul for configuration. |
spring.cloud.consul.config.default-context |
application |
|
spring.cloud.consul.config.enabled |
true |
|
spring.cloud.consul.config.fail-fast |
true |
Throw exceptions during config lookup if true, otherwise, log warnings. |
spring.cloud.consul.config.format |
||
spring.cloud.consul.config.prefix |
config |
|
spring.cloud.consul.config.profile-separator |
, |
|
spring.cloud.consul.config.watch.delay |
1000 |
The value of the fixed delay for the watch in millis. Defaults to 1000. |
spring.cloud.consul.config.watch.enabled |
true |
If the watch is enabled. Defaults to true. |
spring.cloud.consul.config.watch.wait-time |
60 |
The number of seconds to wait (or block) for watch query. Defaults to 60. |
spring.cloud.consul.discovery.acl-token |
||
spring.cloud.consul.discovery.catalog-services-watch-delay |
10 |
|
spring.cloud.consul.discovery.catalog-services-watch-timeout |
2 |
|
spring.cloud.consul.discovery.default-query-tag |
Tag to query for in service list if one is not listed in serverListQueryTags. |
|
spring.cloud.consul.discovery.enabled |
true |
Is service discovery enabled? |
spring.cloud.consul.discovery.health-check-interval |
10s |
How often to perform the health check (e.g. 10s) |
spring.cloud.consul.discovery.health-check-path |
/health |
Alternate server path to invoke for health checking |
spring.cloud.consul.discovery.health-check-timeout |
Timeout for health check (e.g. 10s) |
|
spring.cloud.consul.discovery.health-check-url |
Custom health check url to override default |
|
spring.cloud.consul.discovery.heartbeat.enabled |
false |
|
spring.cloud.consul.discovery.heartbeat.heartbeat-interval |
||
spring.cloud.consul.discovery.heartbeat.interval-ratio |
||
spring.cloud.consul.discovery.heartbeat.ttl-unit |
s |
|
spring.cloud.consul.discovery.heartbeat.ttl-value |
30 |
|
spring.cloud.consul.discovery.host-info |
||
spring.cloud.consul.discovery.hostname |
Hostname to use when accessing server |
|
spring.cloud.consul.discovery.instance-id |
Unique service instance id |
|
spring.cloud.consul.discovery.ip-address |
IP address to use when accessing service (must also set preferIpAddress to use) |
|
spring.cloud.consul.discovery.lifecycle.enabled |
true |
|
spring.cloud.consul.discovery.management-port |
Port to register the management service under (defaults to management port) |
|
spring.cloud.consul.discovery.management-suffix |
management |
Suffix to use when registering management service |
spring.cloud.consul.discovery.management-tags |
Tags to use when registering management service |
|
spring.cloud.consul.discovery.port |
Port to register the service under (defaults to listening port) |
|
spring.cloud.consul.discovery.prefer-agent-address |
false |
Source of how we will determine the address to use |
spring.cloud.consul.discovery.prefer-ip-address |
false |
Use ip address rather than hostname during registration |
spring.cloud.consul.discovery.query-passing |
false |
Add the 'passing` parameter to /v1/health/service/serviceName. This pushes health check passing to the server. |
spring.cloud.consul.discovery.register |
true |
Register as a service in consul. |
spring.cloud.consul.discovery.register-health-check |
true |
Register health check in consul. Useful during development of a service. |
spring.cloud.consul.discovery.scheme |
http |
Whether to register an http or https service |
spring.cloud.consul.discovery.server-list-query-tags |
Map of serviceId’s → tag to query for in server list. This allows filtering services by a single tag. |
|
spring.cloud.consul.discovery.service-name |
Service name |
|
spring.cloud.consul.discovery.tags |
Tags to use when registering service |
|
spring.cloud.consul.enabled |
true |
Is spring cloud consul enabled |
spring.cloud.consul.host |
localhost |
Consul agent hostname. Defaults to 'localhost'. |
spring.cloud.consul.port |
8500 |
Consul agent port. Defaults to '8500'. |
spring.cloud.consul.retry.initial-interval |
1000 |
Initial retry interval in milliseconds. |
spring.cloud.consul.retry.max-attempts |
6 |
Maximum number of attempts. |
spring.cloud.consul.retry.max-interval |
2000 |
Maximum interval for backoff. |
spring.cloud.consul.retry.multiplier |
1.1 |
Multiplier for next interval. |
spring.cloud.hypermedia.refresh.fixed-delay |
5000 |
|
spring.cloud.hypermedia.refresh.initial-delay |
10000 |
|
spring.cloud.inetutils.default-hostname |
localhost |
The default hostname. Used in case of errors. |
spring.cloud.inetutils.default-ip-address |
127.0.0.1 |
The default ipaddress. Used in case of errors. |
spring.cloud.inetutils.ignored-interfaces |
List of Java regex expressions for network interfaces that will be ignored. |
|
spring.cloud.inetutils.timeout-seconds |
1 |
Timeout in seconds for calculating hostname. |
spring.cloud.stream.binders |
||
spring.cloud.stream.bindings |
||
spring.cloud.stream.consul.binder.event-timeout |
5 |
|
spring.cloud.stream.consumer-defaults |
||
spring.cloud.stream.default-binder |
||
spring.cloud.stream.dynamic-destinations |
[] |
|
spring.cloud.stream.ignore-unknown-properties |
true |
|
spring.cloud.stream.instance-count |
1 |
|
spring.cloud.stream.instance-index |
0 |
|
spring.cloud.stream.producer-defaults |
||
spring.cloud.stream.rabbit.binder.admin-adresses |
[] |
|
spring.cloud.stream.rabbit.binder.compression-level |
0 |
|
spring.cloud.stream.rabbit.binder.nodes |
[] |
|
spring.cloud.stream.rabbit.bindings |
||
spring.cloud.zookeeper.base-sleep-time-ms |
50 |
Initial amount of time to wait between retries |
spring.cloud.zookeeper.block-until-connected-unit |
The unit of time related to blocking on connection to Zookeeper |
|
spring.cloud.zookeeper.block-until-connected-wait |
10 |
Wait time to block on connection to Zookeeper |
spring.cloud.zookeeper.connect-string |
localhost:2181 |
Connection string to the Zookeeper cluster |
spring.cloud.zookeeper.default-health-endpoint |
Default health endpoint that will be checked to verify that a dependency is alive |
|
spring.cloud.zookeeper.dependencies |
Mapping of alias to ZookeeperDependency. From Ribbon perspective the alias is actually serviceID since Ribbon can’t accept nested structures in serviceID |
|
spring.cloud.zookeeper.dependency-configurations |
||
spring.cloud.zookeeper.dependency-names |
||
spring.cloud.zookeeper.discovery.enabled |
true |
|
spring.cloud.zookeeper.discovery.instance-host |
Predefined host with which a service can register itself in Zookeeper. Corresponds to the {code address} from the URI spec. |
|
spring.cloud.zookeeper.discovery.instance-port |
Port to register the service under (defaults to listening port) |
|
spring.cloud.zookeeper.discovery.metadata |
Gets the metadata name/value pairs associated with this instance. This information is sent to zookeeper and can be used by other instances. |
|
spring.cloud.zookeeper.discovery.register |
true |
Register as a service in zookeeper. |
spring.cloud.zookeeper.discovery.root |
/services |
Root Zookeeper folder in which all instances are registered |
spring.cloud.zookeeper.discovery.uri-spec |
{scheme}://{address}:{port} |
The URI specification to resolve during service registration in Zookeeper |
spring.cloud.zookeeper.enabled |
true |
Is Zookeeper enabled |
spring.cloud.zookeeper.max-retries |
10 |
Max number of times to retry |
spring.cloud.zookeeper.max-sleep-ms |
500 |
Max time in ms to sleep on each retry |
spring.cloud.zookeeper.prefix |
Common prefix that will be applied to all Zookeeper dependencies' paths |
|
spring.integration.poller.fixed-delay |
1000 |
Fixed delay for default poller. |
spring.integration.poller.max-messages-per-poll |
1 |
Maximum messages per poll for the default poller. |
spring.sleuth.integration.enabled |
true |
Enable Spring Integration sleuth instrumentation. |
spring.sleuth.integration.patterns |
* |
An array of simple patterns against which channel names will be matched. Default is * (all channels). See org.springframework.util.PatternMatchUtils.simpleMatch(String, String). |
spring.sleuth.keys.async.class-name-key |
class |
Simple name of the class with a method annotated with {@code @Async} from which the asynchronous process started @see org.springframework.scheduling.annotation.Async |
spring.sleuth.keys.async.method-name-key |
method |
Name of the method annotated with {@code @Async} @see org.springframework.scheduling.annotation.Async |
spring.sleuth.keys.async.prefix |
Prefix for header names if they are added as tags. |
|
spring.sleuth.keys.async.thread-name-key |
thread |
Name of the thread that executed the async method @see org.springframework.scheduling.annotation.Async |
spring.sleuth.keys.http.headers |
Additional headers that should be added as tags if they exist. If the header value is multi-valued, the tag value will be a comma-separated, single-quoted list. |
|
spring.sleuth.keys.http.host |
http.host |
The domain portion of the URL or host header. Example: "mybucket.s3.amazonaws.com". Used to filter by host as opposed to ip address. |
spring.sleuth.keys.http.method |
http.method |
The HTTP method, or verb, such as "GET" or "POST". Used to filter against an http route. |
spring.sleuth.keys.http.path |
http.path |
The absolute http path, without any query parameters. Example: "/objects/abcd-ff". Used to filter against an http route, portably with zipkin v1. In zipkin v1, only equals filters are supported. Dropping query parameters makes the number of distinct URIs less. For example, one can query for the same resource, regardless of signing parameters encoded in the query line. This does not reduce cardinality to a HTTP single route. For example, it is common to express a route as an http URI template like "/resource/{resource_id}". In systems where only equals queries are available, searching for {@code http.uri=/resource} won’t match if the actual request was "/resource/abcd-ff". Historical note: This was commonly expressed as "http.uri" in zipkin, eventhough it was most often just a path. |
spring.sleuth.keys.http.prefix |
http. |
Prefix for header names if they are added as tags. |
spring.sleuth.keys.http.request-size |
http.request.size |
The size of the non-empty HTTP request body, in bytes. Ex. "16384" <p>Large uploads can exceed limits or contribute directly to latency. |
spring.sleuth.keys.http.response-size |
http.response.size |
The size of the non-empty HTTP response body, in bytes. Ex. "16384" <p>Large downloads can exceed limits or contribute directly to latency. |
spring.sleuth.keys.http.status-code |
http.status_code |
The HTTP response code, when not in 2xx range. Ex. "503" Used to filter for error status. 2xx range are not logged as success codes are less interesting for latency troubleshooting. Omitting saves at least 20 bytes per span. |
spring.sleuth.keys.http.url |
http.url |
The entire URL, including the scheme, host and query parameters if available. Ex. "https://mybucket.s3.amazonaws.com/objects/abcd-ff?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Algorithm=AWS4-HMAC-SHA256…" Combined with {@link #method}, you can understand the fully-qualified request line. This is optional as it may include private data or be of considerable length. |
spring.sleuth.keys.hystrix.command-group |
commandGroup |
Name of the command group. Hystrix uses the command group key to group together commands such as for reporting, alerting, dashboards, or team/library ownership. @see com.netflix.hystrix.HystrixCommandGroupKey |
spring.sleuth.keys.hystrix.command-key |
commandKey |
Name of the command key. Describes the name for the given command. A key to represent a {@link com.netflix.hystrix.HystrixCommand} for monitoring, circuit-breakers, metrics publishing, caching and other such uses. @see com.netflix.hystrix.HystrixCommandKey |
spring.sleuth.keys.hystrix.prefix |
Prefix for header names if they are added as tags. |
|
spring.sleuth.keys.hystrix.thread-pool-key |
threadPoolKey |
Name of the thread pool key. The thread-pool key represents a {@link com.netflix.hystrix.HystrixThreadPool} for monitoring, metrics publishing, caching, and other such uses. A {@link com.netflix.hystrix.HystrixCommand} is associated with a single {@link com.netflix.hystrix.HystrixThreadPool} as retrieved by the {@link com.netflix.hystrix.HystrixThreadPoolKey} injected into it, or it defaults to one created using the {@link com.netflix.hystrix.HystrixCommandGroupKey} it is created with. @see com.netflix.hystrix.HystrixThreadPoolKey |
spring.sleuth.keys.message.headers |
Additional headers that should be added as tags if they exist. If the header value is not a String it will be converted to a String using its toString() method. |
|
spring.sleuth.keys.message.payload.size |
message/payload-size |
An estimate of the size of the payload if available. |
spring.sleuth.keys.message.payload.type |
message/payload-type |
The type of the payload. |
spring.sleuth.keys.message.prefix |
message/ |
Prefix for header names if they are added as tags. |
spring.sleuth.keys.mvc.controller-class |
mvc.controller.class |
The lower case, hyphen delimited name of the class that processes the request. Ex. class named "BookController" will result in "book-controller" tag value. |
spring.sleuth.keys.mvc.controller-method |
mvc.controller.method |
The lower case, hyphen delimited name of the class that processes the request. Ex. method named "listOfBooks" will result in "list-of-books" tag value. |
spring.sleuth.metric.span.accepted-name |
counter.span.accepted |
|
spring.sleuth.metric.span.dropped-name |
counter.span.dropped |
|
spring.sleuth.sampler.percentage |
0.1 |
Percentage of requests that should be sampled. E.g. 1.0 - 100% requests should be sampled. The precision is whole-numbers only (i.e. there’s no support for 0.1% of the traces). |
zuul.add-host-header |
false |
Flag to determine whether the proxy forwards the Host header. |
zuul.add-proxy-headers |
true |
Flag to determine whether the proxy adds X-Forwarded-* headers. |
zuul.host.max-per-route-connections |
20 |
The maximum number of connections that can be used by a single route. |
zuul.host.max-total-connections |
200 |
The maximum number of total connections the proxy can hold open to backends. |
zuul.ignore-local-service |
true |
|
zuul.ignored-headers |
Names of HTTP headers to ignore completely (i.e. leave them out of downstream requests and drop them from downstream responses). |
|
zuul.ignored-patterns |
||
zuul.ignored-services |
Set of service names not to consider for proxying automatically. By default all services in the discovery client will be proxied. |
|
zuul.prefix |
A common prefix for all routes. |
|
zuul.remove-semicolon-content |
true |
Flag to say that path elements past the first semicolon can be dropped. |
zuul.retryable |
Flag for whether retry is supported by default (assuming the routes themselves support it). |
|
zuul.ribbon-isolation-strategy |
||
zuul.routes |
Map of route names to properties. |
|
zuul.security_headers |
Headers that are generally expected to be added by Spring Security, and hence often duplicated if the proxy and the backend are secured with Spring. By default they are added to the ignored headers if Spring Security is present. |
|
zuul.semaphore.max-semaphores |
100 |
The maximum number of total semaphores for Hystrix. |
zuul.sensitive-headers |
List of sensitive headers that are not passed to downstream requests. Defaults to a "safe" set of headers that commonly contain user credentials. It’s OK to remove those from the list if the downstream service is part of the same system as the proxy, so they are sharing authentication data. If using a physical URL outside your own domain, then generally it would be a bad idea to leak user credentials. |
|
zuul.servlet-path |
/zuul |
Path to install Zuul as a servlet (not part of Spring MVC). The servlet is more memory efficient for requests with large bodies, e.g. file uploads. |
zuul.ssl-hostname-validation-enabled |
true |
Flag to say whether the hostname for ssl connections should be verified or not. Default is true. This should only be used in test setups! |
zuul.strip-prefix |
true |
Flag saying whether to strip the prefix from the path before forwarding. |
zuul.trace-request-body |
true |
Flag to say that request bodies can be traced. |