Create a ServiceRegistry interface.

docs/src/main/asciidoc/spring-cloud-commons.adoc

@@ -311,6 +311,20 @@ For a Spring Boot Actuator application there are some additional management endp
 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).
 
 
+=== @EnableDiscoveryClient
+
+Commons provides the `@EnableDiscoveryClient` annotation. This looks for implementations of the `DiscoveryClient` interface via `META-INF/spring.factories`. Implementations of Discovery Client will add a configuration class to `spring.factories` under the `org.springframework.cloud.client.discovery.EnableDiscoveryClient` key. Examples of `DiscoveryClient` implementations: are http://cloud.spring.io/spring-cloud-netflix/[Spring Cloud Netflix Eureka], http://cloud.spring.io/spring-cloud-consul/[Spring Cloud Consul Discovery] and http://cloud.spring.io/spring-cloud-zookeeper/[Spring Cloud Zookeeper Discovery].
+
+By default, implementations of `DiscoveryClient` will auto-register the local Spring Boot server with the remote discovery server. This can be disabled by setting `autoRegister=false` in `@EnableDiscoveryClient`.
+
+=== ServiceRegistry
+
+Commons now provides a `ServiceRegistry` interface which provides methods like `register(Registration)` and `deregister(Registration)` which allow you to provide custom registered services. `Registration` is a marker interface.
+
+==== Service Registry Actuator Endpoint
+
+A `/service-registry` actuator endpoint is provided by Commons. This endpoint relys on a `Registration` bean in the Spring Application Context. Calling `/service-registry/instance-status` via a GET will return the status of the `Registration`. A POST to the same endpoint with a `String` body will change the status of the current `Registration` to the new value. Please see the documentation of the `ServiceRegistry` implementation you are using for the allowed values for updating the status and the values retured for the status.
+
 === 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.

spring-cloud-commons-dependencies/pom.xml

@@ -5,7 +5,7 @@
 	<parent>
 		<artifactId>spring-cloud-dependencies-parent</artifactId>
 		<groupId>org.springframework.cloud</groupId>
-		<version>1.1.2.RELEASE</version>
+		<version>1.2.2.BUILD-SNAPSHOT</version>
         <relativePath/>
 	</parent>
 	<artifactId>spring-cloud-commons-dependencies</artifactId>

spring-cloud-commons/src/main/java/org/springframework/cloud/client/discovery/AbstractDiscoveryLifecycle.java

@@ -26,15 +26,20 @@
 import org.springframework.beans.BeansException;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerInitializedEvent;
 import org.springframework.cloud.client.discovery.event.InstanceRegisteredEvent;
+import org.springframework.cloud.client.serviceregistry.ServiceRegistry;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationListener;
 import org.springframework.core.env.Environment;
 
 /**
  * Lifecycle methods that may be useful and common to various DiscoveryClient implementations.
+ *
+ * @deprecated use {@link org.springframework.cloud.client.serviceregistry.AbstractAutoServiceRegistration} instead. This class will be removed in the next release train.
+ *
  * @author Spencer Gibb
  */
+@Deprecated
 public abstract class AbstractDiscoveryLifecycle implements DiscoveryLifecycle,
 		ApplicationContextAware, ApplicationListener<EmbeddedServletContainerInitializedEvent> {
 
@@ -89,6 +94,9 @@ public void stop(Runnable callback) {
 	@Override
 	public void start() {
 		if (!isEnabled()) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("Discovery Lifecycle disabled. Not starting");
+			}
 			return;
 		}
 
@@ -103,7 +111,7 @@ public void start() {
 			if (shouldRegisterManagement()) {
 				registerManagement();
 			}
-			this.context .publishEvent(new InstanceRegisteredEvent<>(this,
+			this.context.publishEvent(new InstanceRegisteredEvent<>(this,
 					getConfiguration()));
 			this.running.compareAndSet(false, true);
 		}
@@ -113,17 +121,18 @@ public void start() {
 	protected abstract void setConfiguredPort(int port);
 
 	/**
-	 * @return if the management service should be registered with the DiscoveryService
+	 * @return if the management service should be registered with the {@link ServiceRegistry}
 	 */
 	protected boolean shouldRegisterManagement() {
 		return getManagementPort() != null && ManagementServerPortUtils.isDifferent(this.context);
 	}
 
 	/**
-	 * @return the object used to configure the DiscoveryClient
+	 * @return the object used to configure the registration
 	 */
 	protected abstract Object getConfiguration();
 
+
 	/**
 	 * Register the local service with the DiscoveryClient
 	 */
@@ -147,7 +156,7 @@ protected void deregisterManagement() {
 	}
 
 	/**
-	 * @return if the DiscoveryClient is enabled
+	 * @return true, if the {@link DiscoveryLifecycle} is enabled
 	 */
 	protected abstract boolean isEnabled();
 
@@ -201,6 +210,10 @@ public boolean isRunning() {
 		return this.running.get();
 	}
 
+	protected AtomicBoolean getRunning() {
+		return running;
+	}
+
 	@Override
 	public int getOrder() {
 		return this.order;

spring-cloud-commons/src/main/java/org/springframework/cloud/client/discovery/EnableDiscoveryClient.java

@@ -36,4 +36,8 @@
 @Import(EnableDiscoveryClientImportSelector.class)
 public @interface EnableDiscoveryClient {
 
+	/**
+	 * If true, the ServiceRegistry will automatically register the local server.
+	 */
+	boolean autoRegister() default true;
 }

spring-cloud-commons/src/main/java/org/springframework/cloud/client/discovery/EnableDiscoveryClientImportSelector.java

@@ -19,7 +19,13 @@
 import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.cloud.commons.util.SpringFactoryImportSelector;
 import org.springframework.core.Ordered;
+import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.annotation.Order;
+import org.springframework.core.type.AnnotationMetadata;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
 
 /**
  * @author Spencer Gibb
@@ -28,6 +34,24 @@
 public class EnableDiscoveryClientImportSelector
 		extends SpringFactoryImportSelector<EnableDiscoveryClient> {
 
+	@Override
+	public String[] selectImports(AnnotationMetadata metadata) {
+		String[] imports = super.selectImports(metadata);
+
+		AnnotationAttributes attributes = AnnotationAttributes.fromMap(
+				metadata.getAnnotationAttributes(getAnnotationClass().getName(), true));
+
+		boolean autoRegister = attributes.getBoolean("autoRegister");
+
+		if (autoRegister) {
+			List<String> importsList = new ArrayList<>(Arrays.asList(imports));
+			importsList.add("org.springframework.cloud.client.serviceregistry.AutoServiceRegistrationConfiguration");
+			imports = importsList.toArray(new String[0]);
+		}
+
+		return imports;
+	}
+
 	@Override
 	protected boolean isEnabled() {
 		return new RelaxedPropertyResolver(getEnvironment()).getProperty(

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/AbstractAutoServiceRegistration.java

@@ -0,0 +1,74 @@
+package org.springframework.cloud.client.serviceregistry;
+
+import org.springframework.cloud.client.discovery.AbstractDiscoveryLifecycle;
+
+/**
+ * Lifecycle methods that may be useful and common to {@link ServiceRegistry} implementations.
+ *
+ * TODO: document the lifecycle
+ *
+ * @param <R> registration type passed to the {@link ServiceRegistry}.
+ *
+ * @author Spencer Gibb
+ */
+@SuppressWarnings("deprecation")
+public abstract class AbstractAutoServiceRegistration<R extends Registration> extends AbstractDiscoveryLifecycle implements AutoServiceRegistration {
+
+	private ServiceRegistry<R> serviceRegistry;
+
+	protected AbstractAutoServiceRegistration(ServiceRegistry<R> serviceRegistry) {
+		this.serviceRegistry = serviceRegistry;
+	}
+
+	protected ServiceRegistry<R> getServiceRegistry() {
+		return this.serviceRegistry;
+	}
+
+	protected abstract R getRegistration();
+
+	protected abstract R getManagementRegistration();
+
+	/**
+	 * Register the local service with the {@link ServiceRegistry}
+	 */
+	@Override
+	protected void register() {
+		this.serviceRegistry.register(getRegistration());
+	}
+
+	/**
+	 * Register the local management service with the {@link ServiceRegistry}
+	 */
+	@Override
+	protected void registerManagement() {
+		this.serviceRegistry.register(getManagementRegistration());
+	}
+
+	/**
+	 * De-register the local service with the {@link ServiceRegistry}
+	 */
+	@Override
+	protected void deregister() {
+		this.serviceRegistry.deregister(getRegistration());
+	}
+
+	/**
+	 * De-register the local management service with the {@link ServiceRegistry}
+	 */
+	@Override
+	protected void deregisterManagement() {
+		this.serviceRegistry.deregister(getManagementRegistration());
+	}
+
+	@Override
+	public void stop() {
+		if (this.getRunning().compareAndSet(true, false) && isEnabled()) {
+			deregister();
+			if (shouldRegisterManagement()) {
+				deregisterManagement();
+			}
+			this.serviceRegistry.close();
+		}
+	}
+
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/AutoServiceRegistration.java

@@ -0,0 +1,7 @@
+package org.springframework.cloud.client.serviceregistry;
+
+/**
+ * @author Spencer Gibb
+ */
+public interface AutoServiceRegistration {
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/AutoServiceRegistrationConfiguration.java

@@ -0,0 +1,28 @@
+package org.springframework.cloud.client.serviceregistry;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+import javax.annotation.PostConstruct;
+
+/**
+ * @author Spencer Gibb
+ */
+@Configuration
+@EnableConfigurationProperties(AutoServiceRegistrationProperties.class)
+public class AutoServiceRegistrationConfiguration {
+
+	@Autowired(required = false)
+	private AutoServiceRegistration autoServiceRegistration;
+
+	@Autowired
+	private AutoServiceRegistrationProperties properties;
+
+	@PostConstruct
+	protected void init() {
+		if (autoServiceRegistration == null && this.properties.isFailFast()) {
+			throw new IllegalStateException("Auto Service Registration has been requested, but there is no AutoServiceRegistration bean");
+		}
+	}
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/AutoServiceRegistrationProperties.java

@@ -0,0 +1,21 @@
+package org.springframework.cloud.client.serviceregistry;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * @author Spencer Gibb
+ */
+@ConfigurationProperties("spring.cloud.service-registry.auto-registration")
+public class AutoServiceRegistrationProperties {
+
+	/** Should startup fail if there is no AutoServiceRegistration, default to false. */
+	private boolean failFast = false;
+
+	public boolean isFailFast() {
+		return failFast;
+	}
+
+	public void setFailFast(boolean failFast) {
+		this.failFast = failFast;
+	}
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/Registration.java

@@ -0,0 +1,7 @@
+package org.springframework.cloud.client.serviceregistry;
+
+/**
+ * @author Spencer Gibb
+ */
+public interface Registration {
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/ServiceRegistry.java

@@ -0,0 +1,19 @@
+package org.springframework.cloud.client.serviceregistry;
+
+/**
+ * TODO: write javadoc
+ * @author Spencer Gibb
+ */
+public interface ServiceRegistry<R extends Registration> {
+	void register(R registration);
+
+	void deregister(R registration);
+
+	void close();
+
+	// TODO: return value for success?
+	void setStatus(R registration, String status);
+
+	// TODO: concrete return value? Interface?
+	Object getStatus(R registration);
+}

spring-cloud-commons/src/main/java/org/springframework/cloud/client/serviceregistry/ServiceRegistryAutoConfiguration.java

@@ -0,0 +1,28 @@
+package org.springframework.cloud.client.serviceregistry;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.endpoint.Endpoint;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.cloud.client.serviceregistry.endpoint.ServiceRegistryEndpoint;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * @author Spencer Gibb
+ */
+@ConditionalOnBean(ServiceRegistry.class)
+@Configuration
+public class ServiceRegistryAutoConfiguration {
+
+	@Autowired(required = false)
+	private Registration registration;
+
+	@ConditionalOnClass(Endpoint.class)
+	@Bean
+	public ServiceRegistryEndpoint serviceRegistryEndpoint(ServiceRegistry serviceRegistry) {
+		ServiceRegistryEndpoint endpoint = new ServiceRegistryEndpoint(serviceRegistry);
+		endpoint.setRegistration(registration);
+		return endpoint;
+	}
+}