Update Eureka Server's service-urls upon EnvironmentChangeEvent. (#2455)

spring-cloud-netflix-eureka-server/src/main/java/org/springframework/cloud/netflix/eureka/server/EurekaServerAutoConfiguration.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -35,7 +35,9 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.cloud.client.actuator.HasFeatures;
+import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
 import org.springframework.cloud.netflix.eureka.EurekaConstants;
+import org.springframework.context.ApplicationListener;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
 import org.springframework.context.annotation.Configuration;
@@ -67,6 +69,7 @@ import com.sun.jersey.spi.container.servlet.ServletContainer;
 /**
  * @author Gunnar Hillert
  * @author Biju Kunjummen
+ * @author Fahim Farook
  */
 @Configuration
 @Import(EurekaServerInitializerConfiguration.class)
@@ -169,9 +172,68 @@ public class EurekaServerAutoConfiguration extends WebMvcConfigurerAdapter {
 	@ConditionalOnMissingBean
 	public PeerEurekaNodes peerEurekaNodes(PeerAwareInstanceRegistry registry,
 			ServerCodecs serverCodecs) {
-		return new PeerEurekaNodes(registry, this.eurekaServerConfig,
+		return new RefreshablePeerEurekaNodes(registry, this.eurekaServerConfig,
 				this.eurekaClientConfig, serverCodecs, this.applicationInfoManager);
 	}
+	
+	/**
+	 * {@link PeerEurekaNodes} which updates peers when /refresh is invoked.
+	 * Peers are updated only if
+	 * <code>eureka.client.use-dns-for-fetching-service-urls</code> is
+	 * <code>false</code> and one of following properties have changed.
+	 * </p>
+	 * <ul>
+	 * <li><code>eureka.client.availability-zones</code></li>
+	 * <li><code>eureka.client.region</code></li>
+	 * <li><code>eureka.client.service-url.&lt;zone&gt;</code></li>
+	 * </ul>
+	 */
+	static class RefreshablePeerEurekaNodes extends PeerEurekaNodes
+			implements ApplicationListener<EnvironmentChangeEvent> {
+
+		public RefreshablePeerEurekaNodes(
+				final PeerAwareInstanceRegistry registry,
+				final EurekaServerConfig serverConfig,
+				final EurekaClientConfig clientConfig, 
+				final ServerCodecs serverCodecs,
+				final ApplicationInfoManager applicationInfoManager) {
+			super(registry, serverConfig, clientConfig, serverCodecs, applicationInfoManager);
+		}
+
+		@Override
+		public void onApplicationEvent(final EnvironmentChangeEvent event) {
+			if (shouldUpdate(event.getKeys())) {
+				updatePeerEurekaNodes(resolvePeerUrls());
+			}
+		}
+		
+		/*
+		 * Check whether specific properties have changed.
+		 */
+		protected boolean shouldUpdate(final Set<String> changedKeys) {
+			assert changedKeys != null;
+			
+			// if eureka.client.use-dns-for-fetching-service-urls is true, then
+			// service-url will not be fetched from environment.
+			if (clientConfig.shouldUseDnsForFetchingServiceUrls()) {
+				return false;
+			}
+			
+			if (changedKeys.contains("eureka.client.region")) {
+				return true;
+			}
+			
+			for (final String key : changedKeys) {
+				// property keys are not expected to be null.
+				if (key.startsWith("eureka.client.service-url.") ||
+					key.startsWith("eureka.client.availability-zones.")) {
+					return true;
+				}
+			}
+			
+			return false;
+		}
+	}
 
 	@Bean
 	public EurekaServerContext eurekaServerContext(ServerCodecs serverCodecs,

spring-cloud-netflix-eureka-server/src/test/java/org/springframework/cloud/netflix/eureka/server/RefreshablePeerEurekaNodesTests.java

+/*
+ * Copyright 2013-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.springframework.cloud.netflix.eureka.server;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Matchers.anyListOf;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.util.EnvironmentTestUtils;
+import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
+import org.springframework.cloud.netflix.eureka.EurekaClientConfigBean;
+import org.springframework.cloud.netflix.eureka.server.EurekaServerAutoConfiguration.RefreshablePeerEurekaNodes;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.netflix.appinfo.ApplicationInfoManager;
+import com.netflix.discovery.EurekaClientConfig;
+import com.netflix.eureka.EurekaServerConfig;
+import com.netflix.eureka.cluster.PeerEurekaNodes;
+import com.netflix.eureka.registry.PeerAwareInstanceRegistry;
+import com.netflix.eureka.resources.ServerCodecs;
+
+/**
+ * @author Fahim Farook
+ */
+@RunWith(SpringRunner.class)
+@SpringBootTest(
+	classes = RefreshablePeerEurekaNodesTests.Application.class, 
+	webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT, 
+	value = {
+		"spring.application.name=eureka-server",
+		"eureka.client.service-url.defaultZone=http://localhost:8678/eureka/" 
+	})
+public class RefreshablePeerEurekaNodesTests {
+
+	@Autowired
+	private ConfigurableApplicationContext context;
+	
+	@Autowired
+	private PeerEurekaNodes peerEurekaNodes;
+	
+	@Value("${local.server.port}")
+	private int port = 0;
+	
+	private	static final String DEFAULT_ZONE = "eureka.client.service-url.defaultZone";
+	private	static final String REGION = "eureka.client.region";
+	private	static final String USE_DNS = "eureka.client.use-dns-for-fetching-service-urls";
+	
+	@Test
+	public void notUpdatedWhenDnsIsTrue() {		
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=true",
+				"eureka.client.region=unavailable-region", // to force defaultZone 
+				"eureka.client.service-url.defaultZone=http://default-host1:8678/eureka/");
+		this.context.publishEvent(new EnvironmentChangeEvent(new HashSet<String>(Arrays.asList(USE_DNS, DEFAULT_ZONE))));
+		
+		assertFalse("PeerEurekaNodes' are updated when eureka.client.use-dns-for-fetching-service-urls is true",
+				   serviceUrlMatches("http://default-host1:8678/eureka/"));
+	}
+	
+	@Test
+	public void updatedWhenDnsIsFalse() {
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=false",
+				"eureka.client.region=unavailable-region", // to force defaultZone
+				"eureka.client.service-url.defaultZone=http://default-host2:8678/eureka/");
+		this.context.publishEvent(new EnvironmentChangeEvent(new HashSet<String>(Arrays.asList(USE_DNS, DEFAULT_ZONE))));
+		
+		assertTrue("PeerEurekaNodes' are not updated when eureka.client.use-dns-for-fetching-service-urls is false",
+				   serviceUrlMatches("http://default-host2:8678/eureka/"));
+	}
+	
+	
+	@Test
+	public void updatedWhenRegionChanged() {
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=false", 
+				"eureka.client.region=region1",
+				"eureka.client.availability-zones.region1=region1-zone",
+				"eureka.client.availability-zones.region2=region2-zone",
+				"eureka.client.service-url.region1-zone=http://region1-zone-host:8678/eureka/",
+				"eureka.client.service-url.region2-zone=http://region2-zone-host:8678/eureka/");
+		this.context.publishEvent(new EnvironmentChangeEvent(Collections.singleton(REGION)));
+		assertTrue("PeerEurekaNodes' are not updated when eureka.client.region is changed",
+				   serviceUrlMatches("http://region1-zone-host:8678/eureka/"));
+		
+		changeProperty("eureka.client.region=region2");
+		this.context.publishEvent(new EnvironmentChangeEvent(Collections.singleton(REGION)));
+		assertTrue("PeerEurekaNodes' are not updated when eureka.client.region is changed",
+				   serviceUrlMatches("http://region2-zone-host:8678/eureka/"));
+	}
+	
+	@Test
+	public void updatedWhenAvailabilityZoneChanged() {
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=false", 
+				"eureka.client.region=region4",
+				"eureka.client.availability-zones.region3=region3-zone",
+				"eureka.client.service-url.region4-zone=http://region4-zone-host:8678/eureka/",
+				"eureka.client.service-url.defaultZone=http://default-host3:8678/eureka/");
+		this.context.publishEvent(new EnvironmentChangeEvent(Collections.singleton("eureka.client.availability-zones.region3")));
+		assertTrue(this.peerEurekaNodes.getPeerEurekaNodes().get(0).getServiceUrl().equals("http://default-host3:8678/eureka/"));
+		
+		changeProperty("eureka.client.availability-zones.region4=region4-zone");
+		this.context.publishEvent(new EnvironmentChangeEvent(Collections.singleton("eureka.client.availability-zones.region4")));
+		assertTrue("PeerEurekaNodes' are not updated when eureka.client.availability-zones are changed",
+				   serviceUrlMatches("http://region4-zone-host:8678/eureka/"));
+	}
+		
+	@Test
+	public void notUpdatedWhenIrrelevantPropertiesChanged() {
+		// Only way to test this is verifying whether updatePeerEurekaNodes() is invoked.
+		
+		// PeerEurekaNodes.updatePeerEurekaNodes() is not public, hence cannot verify with Mockito.
+		class VerifyablePeerEurekNode extends RefreshablePeerEurekaNodes {
+			public VerifyablePeerEurekNode(PeerAwareInstanceRegistry registry, EurekaServerConfig serverConfig,
+										   EurekaClientConfig clientConfig, ServerCodecs serverCodecs,
+										   ApplicationInfoManager applicationInfoManager) {
+				super(registry, serverConfig, clientConfig, serverCodecs, applicationInfoManager);
+			}
+
+			protected void updatePeerEurekaNodes(List<String> newPeerUrls) {
+				super.updatePeerEurekaNodes(newPeerUrls);
+			}
+		}
+		
+		// Create stubs.
+		final EurekaClientConfigBean configClientBean = mock(EurekaClientConfigBean.class);
+		when(configClientBean.isUseDnsForFetchingServiceUrls()).thenReturn(false);
+		final VerifyablePeerEurekNode mock = spy(new VerifyablePeerEurekNode(null, null, configClientBean, null, null));		
+		
+		mock.onApplicationEvent(new EnvironmentChangeEvent(Collections.singleton("some.irrelevant.property")));	
+		verify(mock, never()).updatePeerEurekaNodes(anyListOf(String.class));
+	}
+	
+	@Test
+	public void peerEurekaNodesIsRefreshablePeerEurekaNodes() {
+		assertNotNull(this.peerEurekaNodes);
+		assertTrue("PeerEurekaNodes should be an instance of RefreshablePeerEurekaNodes",
+				   this.peerEurekaNodes instanceof RefreshablePeerEurekaNodes);
+	}
+	
+	
+	@Test
+	public void serviceUrlsCountAsSoonAsRefreshed() {
+		changeProperty("eureka.client.service-url.defaultZone=http://defaul-host3:8678/eureka/,http://defaul-host4:8678/eureka/");
+		forceUpdate();
+		assertThat("PeerEurekaNodes' peer count is incorrect.", 
+				   this.peerEurekaNodes.getPeerEurekaNodes().size(), is(2));
+	}
+	
+	
+	@Test
+	public void serviceUrlsValueAsSoonAsRefreshed() {
+		changeProperty("eureka.client.service-url.defaultZone=http://defaul-host4:8678/eureka/");
+		forceUpdate();
+		assertTrue("PeerEurekaNodes' new peer[0] is incorrect",
+				   serviceUrlMatches("http://defaul-host4:8678/eureka/"));
+	}
+	
+	@Test
+	public void dashboardUpdatedAsSoonAsRefreshed() {
+		changeProperty("eureka.client.service-url.defaultZone=http://defaul-host5:8678/eureka/");
+		forceUpdate();
+		final ResponseEntity<String> entity = new TestRestTemplate()
+				.getForEntity("http://localhost:" + this.port + "/", String.class);
+		assertEquals(HttpStatus.OK, entity.getStatusCode());
+		final String body = entity.getBody();
+		assertNotNull(body);
+		assertTrue("DS Replicas not updated in the Eureka Server dashboard", 
+				   body.contains("http://defaul-host5:8678/eureka/"));
+	}
+	
+	@Test
+	public void notUpdatedForRelaxedKeys() {
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=false",
+				"eureka.client.region=unavailable-region", // to force defaultZone
+				"eureka.client.service-url.defaultZone=http://defaul-host6:8678/eureka/");
+		this.context.publishEvent(new EnvironmentChangeEvent(Collections.singleton("eureka.client.serviceUrl.defaultZone")));
+		assertFalse("PeerEurekaNodes' are updated for keys with relaxed binding",
+				   serviceUrlMatches("http://defaul-host6:8678/eureka/"));
+	}
+	
+	@EnableEurekaServer
+	@Configuration
+	@EnableAutoConfiguration(exclude = {
+			org.springframework.boot.autoconfigure.security.SecurityAutoConfiguration.class,
+			org.springframework.boot.actuate.autoconfigure.ManagementWebSecurityAutoConfiguration.class })
+	protected static class Application {
+
+		public static void main(String[] args) {
+			new SpringApplicationBuilder(RefreshablePeerEurekaNodesTests.Application.class).run(args);
+		}
+	}
+
+	/*
+	 * Changes the value of given key in the environment.
+	 */
+	private void changeProperty(final String... pairs) {
+		EnvironmentTestUtils.addEnvironment(this.context, pairs);
+	}
+
+	/*
+	 * Refreshes the context with properties satisfying to invoke update.
+	 */
+	private void forceUpdate() {
+		changeProperty(
+				"eureka.client.use-dns-for-fetching-service-urls=false",
+				"eureka.client.region=unavailable-region"); // to force defaultZone
+		this.context.publishEvent(
+				new EnvironmentChangeEvent(Collections.singleton("eureka.client.service-url.defaultZone")));
+	}
+	
+	/*
+	 * Whether the first element in PeerEurekaNodes matches the given url.
+	 */
+	private boolean serviceUrlMatches(final String serviceUrl) {
+		return this.peerEurekaNodes.getPeerEurekaNodes().get(0).getServiceUrl().equals(serviceUrl);
+	}
+}