spring-cloudGH-140: Support for Composite Discovery client (spring-cl…

…oud#198)

Add support for Composite Discovery client

* Test that the default discovery client is  present

* Return a local Service instance from Composite Discovery Client

fixes spring-cloudgh-140

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

@@ -0,0 +1,73 @@
+package org.springframework.cloud.client.discovery.composite;
+
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.List;
+
+/**
+ * A {@link DiscoveryClient} composed of other Discovery Client's and will delegate the
+ * calls to each of them in order
+ * 
+ * @author Biju Kunjummen
+ */
+public class CompositeDiscoveryClient implements DiscoveryClient {
+
+	private final List<DiscoveryClient> discoveryClients;
+
+	public CompositeDiscoveryClient(List<DiscoveryClient> discoveryClients) {
+		this.discoveryClients = discoveryClients;
+	}
+
+	@Override
+	public String description() {
+		return "Composite Discovery Client";
+	}
+
+	@Override
+	public ServiceInstance getLocalServiceInstance() {
+		if (this.discoveryClients != null) {
+			for (DiscoveryClient discoveryClient : discoveryClients) {
+				ServiceInstance serviceInstance = discoveryClient.getLocalServiceInstance();
+				if (serviceInstance != null) {
+					return serviceInstance;
+				}
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public List<ServiceInstance> getInstances(String serviceId) {
+		if (this.discoveryClients != null) {
+			for (DiscoveryClient discoveryClient : discoveryClients) {
+				List<ServiceInstance> instances = discoveryClient.getInstances(serviceId);
+				if (instances != null && instances.size() > 0) {
+					return instances;
+				}
+			}
+		}
+		return Collections.emptyList();
+	}
+
+	@Override
+	public List<String> getServices() {
+		LinkedHashSet<String> services = new LinkedHashSet<>();
+		if (this.discoveryClients != null) {
+			for (DiscoveryClient discoveryClient : discoveryClients) {
+				List<String> serviceForClient = discoveryClient.getServices();
+				if (serviceForClient != null) {
+					services.addAll(serviceForClient);
+				}
+			}
+		}
+		return new ArrayList<>(services);
+	}
+
+	List<DiscoveryClient> getDiscoveryClients() {
+		return discoveryClients;
+	}
+}

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

@@ -0,0 +1,28 @@
+package org.springframework.cloud.client.discovery.composite;
+
+import org.springframework.boot.autoconfigure.AutoConfigureBefore;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClientAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Primary;
+
+import java.util.List;
+
+/**
+ * Auto-configuration for Composite Discovery Client.
+ * 
+ * @author Biju Kunjummen
+ */
+
+@Configuration
+@AutoConfigureBefore(SimpleDiscoveryClientAutoConfiguration.class)
+public class CompositeDiscoveryClientAutoConfiguration {
+
+	@Bean
+	@Primary
+	public CompositeDiscoveryClient compositeDiscoveryClient(List<DiscoveryClient> discoveryClients) {
+		return new CompositeDiscoveryClient(discoveryClients);
+	}
+
+}

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

@@ -1,32 +1,30 @@
 package org.springframework.cloud.client.discovery.simple;
 
-import java.net.URI;
-
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.autoconfigure.AutoConfigureBefore;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
 import org.springframework.boot.context.embedded.EmbeddedServletContainer;
 import org.springframework.boot.context.embedded.EmbeddedWebApplicationContext;
-import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.client.discovery.DiscoveryClient;
 import org.springframework.cloud.client.discovery.noop.NoopDiscoveryClientAutoConfiguration;
 import org.springframework.cloud.commons.util.InetUtils;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
 import org.springframework.util.ClassUtils;
 
+import java.net.URI;
+
 /**
  * Spring Boot Auto-Configuration for Simple Properties based Discovery Client
  *
  * @author Biju Kunjummen
  */
 
 @Configuration
-@ConditionalOnMissingBean(DiscoveryClient.class)
-@EnableConfigurationProperties
 @AutoConfigureBefore(NoopDiscoveryClientAutoConfiguration.class)
 public class SimpleDiscoveryClientAutoConfiguration {
 
@@ -54,9 +52,9 @@ public SimpleDiscoveryProperties simpleDiscoveryProperties() {
 	}
 
 	@Bean
-	public DiscoveryClient simpleDiscoveryClient(
-			SimpleDiscoveryProperties simpleDiscoveryProperties) {
-		return new SimpleDiscoveryClient(simpleDiscoveryProperties);
+	@Order(Ordered.LOWEST_PRECEDENCE)
+	public DiscoveryClient simpleDiscoveryClient() {
+		return new SimpleDiscoveryClient(simpleDiscoveryProperties());
 	}
 
 	private int findPort() {

spring-cloud-commons/src/main/resources/META-INF/spring.factories

@@ -7,6 +7,7 @@ org.springframework.cloud.client.loadbalancer.AsyncLoadBalancerAutoConfiguration
 org.springframework.cloud.client.loadbalancer.LoadBalancerAutoConfiguration,\
 org.springframework.cloud.client.serviceregistry.ServiceRegistryAutoConfiguration,\
 org.springframework.cloud.commons.util.UtilAutoConfiguration,\
+org.springframework.cloud.client.discovery.composite.CompositeDiscoveryClientAutoConfiguration,\
 org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClientAutoConfiguration
 
 

spring-cloud-commons/src/test/java/org/springframework/cloud/client/discovery/composite/CompositeDiscoveryClientAutoConfigurationTests.java

@@ -0,0 +1,79 @@
+package org.springframework.cloud.client.discovery.composite;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.springframework.cloud.client.discovery.simple.SimpleDiscoveryClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Composite Discovery Client should be the one found by default.
+ * 
+ * @author Biju Kunjummen
+ */
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+public class CompositeDiscoveryClientAutoConfigurationTests {
+
+	@Autowired
+	private DiscoveryClient discoveryClient;
+
+	@Test
+	public void compositeDiscoveryClientShouldBeTheDefault() {
+		assertThat(discoveryClient).isInstanceOf(CompositeDiscoveryClient.class);
+		CompositeDiscoveryClient compositeDiscoveryClient = (CompositeDiscoveryClient) discoveryClient;
+		assertThat(compositeDiscoveryClient.getDiscoveryClients()).hasSize(2);
+		assertThat(compositeDiscoveryClient.getDiscoveryClients().get(0).description())
+				.isEqualTo("A custom discovery client");
+	}
+
+	@Test
+	public void simpleDiscoveryClientShouldBeHaveTheLowestPrecedence() {
+		CompositeDiscoveryClient compositeDiscoveryClient = (CompositeDiscoveryClient) discoveryClient;
+		assertThat(compositeDiscoveryClient.getDiscoveryClients().get(0).description())
+				.isEqualTo("A custom discovery client");
+		assertThat(compositeDiscoveryClient.getDiscoveryClients().get(1))
+				.isInstanceOf(SimpleDiscoveryClient.class);
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	public static class Config {
+
+		@Bean
+		public DiscoveryClient customDiscoveryClient1() {
+			return new DiscoveryClient() {
+				@Override
+				public String description() {
+					return "A custom discovery client";
+				}
+
+				@Override
+				public ServiceInstance getLocalServiceInstance() {
+					return null;
+				}
+
+				@Override
+				public List<ServiceInstance> getInstances(String serviceId) {
+					return null;
+				}
+
+				@Override
+				public List<String> getServices() {
+					return null;
+				}
+			};
+		}
+	}
+}

spring-cloud-commons/src/test/java/org/springframework/cloud/client/discovery/composite/CompositeDiscoveryClientTests.java

@@ -0,0 +1,116 @@
+package org.springframework.cloud.client.discovery.composite;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.client.DefaultServiceInstance;
+import org.springframework.cloud.client.ServiceInstance;
+import org.springframework.cloud.client.discovery.DiscoveryClient;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.annotation.Order;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.net.URI;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for behavior of Composite Discovery Client
+ * 
+ * @author Biju Kunjummen
+ */
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(properties = {
+		"spring.application.name=service0",
+		"spring.cloud.discovery.client.simple.instances.service1[0].uri=http://s1-1:8080",
+		"spring.cloud.discovery.client.simple.instances.service1[1].uri=https://s1-2:8443",
+		"spring.cloud.discovery.client.simple.instances.service2[0].uri=https://s2-1:8080",
+		"spring.cloud.discovery.client.simple.instances.service2[1].uri=https://s2-2:443" })
+public class CompositeDiscoveryClientTests {
+
+	@Autowired
+	private DiscoveryClient discoveryClient;
+
+	@Test
+	public void getInstancesByServiceIdShouldDelegateCall() {
+		assertThat(this.discoveryClient).isInstanceOf(CompositeDiscoveryClient.class);
+
+		assertThat(this.discoveryClient.getInstances("service1")).hasSize(2);
+
+		ServiceInstance s1 = this.discoveryClient.getInstances("service1").get(0);
+		assertThat(s1.getHost()).isEqualTo("s1-1");
+		assertThat(s1.getPort()).isEqualTo(8080);
+		assertThat(s1.getUri()).isEqualTo(URI.create("http://s1-1:8080"));
+		assertThat(s1.isSecure()).isEqualTo(false);
+	}
+
+	@Test
+	public void getServicesShouldAggregateAllServiceNames() {
+		assertThat(this.discoveryClient.getServices()).containsOnlyOnce("service1", "service2", "custom");
+	}
+
+	@Test
+	public void getDescriptionShouldBeComposite() {
+		assertThat(this.discoveryClient.description()).isEqualTo("Composite Discovery Client");
+	}
+
+	@Test
+	public void getInstancesShouldRespectOrder() {
+		assertThat(this.discoveryClient.getInstances("custom")).hasSize(1);
+		assertThat(this.discoveryClient.getInstances("custom")).hasSize(1);
+	}
+
+	@Test
+	public void getInstancesByUnknownServiceIdShouldReturnAnEmptyList() {
+		assertThat(this.discoveryClient.getInstances("unknown")).hasSize(0);
+	}
+
+
+	@Test
+	public void localServiceInstanceShouldReturnTheFirstMatch() {
+		assertThat(this.discoveryClient.getLocalServiceInstance().getServiceId()).isEqualTo("service0");
+	}
+
+	@EnableAutoConfiguration
+	@Configuration
+	public static class Config {
+
+		@Bean
+		@Order(1)
+		public DiscoveryClient customDiscoveryClient() {
+			return new DiscoveryClient() {
+				@Override
+				public String description() {
+					return "A custom discovery client";
+				}
+
+				@Override
+				public ServiceInstance getLocalServiceInstance() {
+					return null;
+				}
+
+				@Override
+				public List<ServiceInstance> getInstances(String serviceId) {
+					if (serviceId.equals("custom")) {
+						ServiceInstance s1 = new DefaultServiceInstance("custom", "host",
+								123, false);
+						return Arrays.asList(s1);
+					}
+					return Collections.emptyList();
+				}
+
+				@Override
+				public List<String> getServices() {
+					return Arrays.asList("custom");
+				}
+			};
+		}
+	}
+}