Configuration for Spring Cloud Gateway is driven by a collection of RouteDefinitionLocators.
RouteDefinitionLocator.java.
public interface RouteDefinitionLocator {
Flux<RouteDefinition> getRouteDefinitions();
}
By default, a PropertiesRouteDefinitionLocator loads properties using Spring Boot’s @ConfigurationProperties mechanism.
The configuration examples above all use a shortcut notation that uses positional arguments rather than named ones. The two examples below are equivalent:
application.yml.
spring:
cloud:
gateway:
routes:
- id: setstatus_route
uri: https://example.org
filters:
- name: SetStatus
args:
status: 401
- id: setstatusshortcut_route
uri: https://example.org
filters:
- SetStatus=401
For some usages of the gateway, properties will be adequate, but some production use cases will benefit from loading configuration from an external source, such as a database. Future milestone versions will have RouteDefinitionLocator implementations based off of Spring Data Repositories such as: Redis, MongoDB and Cassandra.
10.1 Fluent Java Routes API
To allow for simple configuration in Java, there is a fluent API defined in the RouteLocatorBuilder bean.
GatewaySampleApplication.java.
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder, ThrottleGatewayFilterFactory throttle) {
return builder.routes()
.route(r -> r.host("**.abc.org").and().path("/image/png")
.filters(f ->
f.addResponseHeader("X-TestHeader", "foobar"))
.uri("http://httpbin.org:80")
)
.route(r -> r.path("/image/webp")
.filters(f ->
f.addResponseHeader("X-AnotherHeader", "baz"))
.uri("http://httpbin.org:80")
)
.route(r -> r.order(-1)
.host("**.throttle.org").and().path("/get")
.filters(f -> f.filter(throttle.apply(1,
1,
10,
TimeUnit.SECONDS)))
.uri("http://httpbin.org:80")
)
.build();
}
This style also allows for more custom predicate assertions. The predicates defined by RouteDefinitionLocator beans are combined using logical and. By using the fluent Java API, you can use the and(), or() and negate() operators on the Predicate class.
10.2 DiscoveryClient Route Definition Locator
The Gateway can be configured to create routes based on services registered with a DiscoveryClient compatible service registry.
To enable this, set spring.cloud.gateway.discovery.locator.enabled=true and make sure a DiscoveryClient implementation is on the classpath and enabled (such as Netflix Eureka, Consul or Zookeeper).
10.2.1 Configuring Predicates and Filters For DiscoveryClient Routes
By default the Gateway defines a single predicate and filter for routes created via a DiscoveryClient.
The default predicate is a path predicate defined with the pattern /serviceId/**, where serviceId is
the id of the service from the DiscoveryClient.
The default filter is rewrite path filter with the regex /serviceId/(?<remaining>.*) and the replacement
/${remaining}. This just strips the service id from the path before the request is sent
downstream.
If you would like to customize the predicates and/or filters used by the DiscoveryClient routes you can do so
by setting spring.cloud.gateway.discovery.locator.predicates[x] and spring.cloud.gateway.discovery.locator.filters[y].
When doing so you need to make sure to include the default predicate and filter above, if you want to retain
that functionality. Below is an example of what this looks like.
application.properties.
spring.cloud.gateway.discovery.locator.predicates[0].name: Path
spring.cloud.gateway.discovery.locator.predicates[0].args[pattern]: "'/'+serviceId+'/**'"
spring.cloud.gateway.discovery.locator.predicates[1].name: Host
spring.cloud.gateway.discovery.locator.predicates[1].args[pattern]: "'**.foo.com'"
spring.cloud.gateway.discovery.locator.filters[0].name: Hystrix
spring.cloud.gateway.discovery.locator.filters[0].args[name]: serviceId
spring.cloud.gateway.discovery.locator.filters[1].name: RewritePath
spring.cloud.gateway.discovery.locator.filters[1].args[regexp]: "'/' + serviceId + '/(?<remaining>.*)'"
spring.cloud.gateway.discovery.locator.filters[1].args[replacement]: "'/${remaining}'"