Spring Cloud client applications calling a microservice should be interested on relying on a client load-balancing
feature in order to automatically discover at which endpoint(s) it can reach a given service. This mechanism has been
implemented within the [spring-cloud-kubernetes-ribbon](spring-cloud-kubernetes-ribbon/pom.xml) project where a
Kubernetes client will populate a Ribbon ServerList
containing information
about such endpoints.
The implementation is part of the following starter that you can use by adding its dependency to your pom file:
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-kubernetes-ribbon</artifactId> <version>${latest.version}</version> </dependency>
When the list of the endpoints is populated, the Kubernetes client will search the registered endpoints living in the current namespace/project matching the service name defined using the Ribbon Client annotation:
@RibbonClient(name = "name-service")
You can configure Ribbon’s behavior by providing properties in your application.properties
(via your application’s
dedicated ConfigMap
) using the following format: <name of your service>.ribbon.<Ribbon configuration key>
where:
<name of your service>
corresponds to the service name you’re accessing over Ribbon, as configured using the
@RibbonClient
annotation (e.g. name-service
in the example above)<Ribbon configuration key>
is one of the Ribbon configuration key defined by
Ribbon’s CommonClientConfigKey classAdditionally, the spring-cloud-kubernetes-ribbon
project defines two additional configuration keys to further
control how Ribbon interacts with Kubernetes. In particular, if an endpoint defines multiple ports, the default
behavior is to use the first one found. To select more specifically which port to use, in a multi-port service, use
the PortName
key. If you want to specify in which Kubernetes' namespace the target service should be looked up, use
the KubernetesNamespace
key, remembering in both instances to prefix these keys with your service name and
ribbon
prefix as specified above.
Examples that are using this module for ribbon discovery are:
Note: The Ribbon discovery client can be disabled by setting this key within the application properties file
spring.cloud.kubernetes.ribbon.enabled=false
.