158. Spring Cloud Config

Spring Cloud GCP makes it possible to use the Google Runtime Configuration API as a Spring Cloud Config server to remotely store your application configuration data.

The Spring Cloud GCP Config support is provided via its own Spring Boot starter. It enables the use of the Google Runtime Configuration API as a source for Spring Boot configuration properties.

[Note]Note

The Google Cloud Runtime Configuration service is in beta status.

Maven coordinates, using Spring Cloud GCP BOM:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-gcp-starter-config</artifactId>
</dependency>

Gradle coordinates:

dependencies {
    compile group: 'org.springframework.cloud', name: 'spring-cloud-gcp-starter-config'
}

158.1 Configuration

The following parameters are configurable in Spring Cloud GCP Config:

Name

Description

Required

Default value

spring.cloud.gcp.config.enabled

Enables the Config client

No

false

spring.cloud.gcp.config.name

Name of your application

No

Value of the spring.application.name property. If none, application

spring.cloud.gcp.config.profile

Active profile

No

Value of the spring.profiles.active property. If more than a single profile, last one is chosen

spring.cloud.gcp.config.timeout-millis

Timeout in milliseconds for connecting to the Google Runtime Configuration API

No

60000

spring.cloud.gcp.config.project-id

GCP project ID where the Google Runtime Configuration API is hosted

No

 

spring.cloud.gcp.config.credentials.location

OAuth2 credentials for authenticating with the Google Runtime Configuration API

No

 

spring.cloud.gcp.config.credentials.encoded-key

Base64-encoded OAuth2 credentials for authenticating with the Google Runtime Configuration API

No

 

spring.cloud.gcp.config.credentials.scopes

OAuth2 scope for Spring Cloud GCP Config credentials

No

https://www.googleapis.com/auth/cloudruntimeconfig

[Note]Note

These properties should be specified in a bootstrap.yml/bootstrap.properties file, rather than the usual applications.yml/application.properties.

[Note]Note

Core properties, as described in Spring Cloud GCP Core Module, do not apply to Spring Cloud GCP Config.

158.2 Quick start

  1. Create a configuration in the Google Runtime Configuration API that is called ${spring.application.name}_${spring.profiles.active}. In other words, if spring.application.name is myapp and spring.profiles.active is prod, the configuration should be called myapp_prod.

    In order to do that, you should have the Google Cloud SDK installed, own a Google Cloud Project and run the following command:

gcloud init # if this is your first Google Cloud SDK run.
gcloud beta runtime-config configs create myapp_prod
gcloud beta runtime-config configs variables set myapp.queue-size 25 --config-name myapp_prod
  1. Configure your bootstrap.properties file with your application’s configuration data:

    spring.application.name=myapp
    spring.profiles.active=prod
  2. Add the @ConfigurationProperties annotation to a Spring-managed bean:

    @Component
    @ConfigurationProperties("myapp")
    public class SampleConfig {
    
      private int queueSize;
    
      public int getQueueSize() {
        return this.queueSize;
      }
    
      public void setQueueSize(int queueSize) {
        this.queueSize = queueSize;
      }
    }

When your Spring application starts, the queueSize field value will be set to 25 for the above SampleConfig bean.

158.3 Refreshing the configuration at runtime

Spring Cloud provides support to have configuration parameters be reloadable with the POST request to /actuator/refresh endpoint.

  1. Add the Spring Boot Actuator dependency:

Maven coordinates:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

Gradle coordinates:

dependencies {
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-actuator'
}
  1. Add @RefreshScope to your Spring configuration class to have parameters be reloadable at runtime.
  2. Add management.endpoints.web.exposure.include=refresh to your application.properties to allow unrestricted access to /actuator/refresh.
  3. Update a property with gcloud:

    $ gcloud beta runtime-config configs variables set \
      myapp.queue_size 200 \
      --config-name myapp_prod
  4. Send a POST request to the refresh endpoint:

    $ curl -XPOST http://myapp.host.com/actuator/refresh

158.4 Sample

A sample application and a codelab are available.