75. Spring Cloud Zookeeper and Service Registry

Spring Cloud Zookeeper implements the ServiceRegistry interface, letting developers register arbitrary services in a programmatic way.

The ServiceInstanceRegistration class offers a builder() method to create a Registration object that can be used by the ServiceRegistry , as shown in the following example:

@Autowired
private ZookeeperServiceRegistry serviceRegistry;

public void registerThings() {
    ZookeeperRegistration registration = ServiceInstanceRegistration.builder()
            .defaultUriSpec()
            .address("anyUrl")
            .port(10)
            .name("/a/b/c/d/anotherservice")
            .build();
    this.serviceRegistry.register(registration);
}

75.1 Instance Status

Netflix Eureka supports having instances that are OUT_OF_SERVICE registered with the server. These instances are not returned as active service instances. This is useful for behaviors such as blue/green deployments. (Note that the Curator Service Discovery recipe does not support this behavior.) Taking advantage of the flexible payload has let Spring Cloud Zookeeper implement OUT_OF_SERVICE by updating some specific metadata and then filtering on that metadata in the Ribbon ZookeeperServerList . The ZookeeperServerList filters out all non-null instance statuses that do not equal UP . If the instance status field is empty, it is considered to be UP for backwards compatibility. To change the status of an instance, make a POST with OUT_OF_SERVICE to the ServiceRegistry instance status actuator endpoint, as shown in the following example:

$ http POST http://localhost:8081/service-registry status=OUT_OF_SERVICE

The preceding example uses the http command from https://httpie.org .