Gh 3718 add zoned loadbalancer instrumentation

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

@@ -335,6 +335,18 @@ When a refresh occurs clients will be unregistered from the Eureka server and th
 where all instance of a given service are not available. One way to eliminate this from happening is to disable
 the ability to refresh Eureka clients.  To do this set `eureka.client.refresh.enable=false`.
 
+=== Using Eureka with Spring Cloud LoadBalancer
+
+We offer support for the Spring Cloud LoadBalancer `ZonePreferenceServiceInstanceListSupplier`.
+The `zone` value from the Eureka instance metadata (`eureka.instance.metadataMap.zone`) is used for setting the
+value of `spring-clod-loadbalancer-zone` property that is used to filter service instances by zone.
+
+If that is missing and if the `spring.cloud.loadbalancer.eureka.approximateZoneFromHostname` flag is set to `true`,
+it can use the domain name from the server hostname as a proxy for the zone.
+
+If there is no other source of zone data, then a guess is made, based on the client configuration (as opposed to the instance configuration).
+We take `eureka.client.availabilityZones`, which is a map from region name to a list of zones, and pull out the first zone for the instance's own region (that is, the `eureka.client.region`, which defaults to "us-east-1", for compatibility with native Netflix).
+
 [[spring-cloud-eureka-server]]
 == Service Discovery: Eureka Server
 

spring-cloud-netflix-eureka-client/pom.xml

@@ -51,6 +51,11 @@
 			<artifactId>spring-cloud-config-server</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-loadbalancer</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>com.netflix.eureka</groupId>
 			<artifactId>eureka-client</artifactId>

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/loadbalancer/EurekaLoadBalancerClientConfiguration.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2013-2019 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
+ *
+ *      https://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.loadbalancer;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import javax.annotation.PostConstruct;
+
+import com.netflix.appinfo.EurekaInstanceConfig;
+import com.netflix.discovery.EurekaClientConfig;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cloud.netflix.ribbon.eureka.ZoneUtils;
+import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.core.env.MapPropertySource;
+import org.springframework.core.env.MutablePropertySources;
+import org.springframework.util.StringUtils;
+
+/**
+ * A configuration for Spring Cloud LoadBalancer that retrieves client instance zone from
+ * Eureka and sets it as a property. Based on
+ * {@link EurekaLoadBalancerClientConfiguration}.
+ *
+ * @author Olga Maciaszek-Sharma
+ * @since 2.2.1
+ * @see EurekaLoadBalancerClientConfiguration
+ */
+public class EurekaLoadBalancerClientConfiguration {
+
+	// Visible for tests
+	static final String LOADBALANCER_ZONE = "spring.cloud.loadbalancer.zone";
+
+	// Visible for tests
+	static final String APPROXIMATE_ZONE_FROM_HOSTNAME = "spring.cloud.loadbalancer.eureka.approximateZoneFromHostname";
+
+	private static final Log LOG = LogFactory
+			.getLog(EurekaLoadBalancerClientConfiguration.class);
+
+	private final EurekaClientConfig clientConfig;
+
+	private final EurekaInstanceConfig eurekaConfig;
+
+	private final ConfigurableEnvironment environment;
+
+	public EurekaLoadBalancerClientConfiguration(
+			@Autowired(required = false) EurekaClientConfig clientConfig,
+			@Autowired(required = false) EurekaInstanceConfig eurekaInstanceConfig,
+			ConfigurableEnvironment environment) {
+		this.clientConfig = clientConfig;
+		this.eurekaConfig = eurekaInstanceConfig;
+		this.environment = environment;
+	}
+
+	@PostConstruct
+	public void preprocess() {
+		if (!StringUtils.isEmpty(environment.getProperty(LOADBALANCER_ZONE))) {
+			return;
+		}
+		String zone = getZoneFromEureka();
+		if (zone != null) {
+			if (LOG.isDebugEnabled()) {
+				LOG.debug("Setting the value of '" + LOADBALANCER_ZONE + "' to " + zone);
+			}
+			addZoneProperty(zone);
+		}
+	}
+
+	private void addZoneProperty(String zone) {
+		MutablePropertySources propertySources = environment.getPropertySources();
+		Map<String, Object> myMap = new HashMap<>();
+		myMap.put(LOADBALANCER_ZONE, zone);
+		propertySources.addLast(new MapPropertySource("LOADBALANCER_MAP", myMap));
+	}
+
+	private String getZoneFromEureka() {
+		String zone;
+		boolean approximateZoneFromHostname = Boolean.parseBoolean(
+				environment.getProperty(APPROXIMATE_ZONE_FROM_HOSTNAME, "false"));
+		if (approximateZoneFromHostname && eurekaConfig != null) {
+			return ZoneUtils.extractApproximateZone(this.eurekaConfig.getHostName(false));
+		}
+		else {
+			zone = eurekaConfig == null ? null
+					: eurekaConfig.getMetadataMap().get("zone");
+			if (zone == null) {
+				String[] zones = clientConfig
+						.getAvailabilityZones(clientConfig.getRegion());
+				// Pick the first one from the regions we want to connect to
+				zone = zones != null && zones.length > 0 ? zones[0] : null;
+			}
+			return zone;
+		}
+	}
+
+}

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/loadbalancer/LoadBalancerEurekaAutoConfiguration.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2013-2019 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
+ *
+ *      https://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.loadbalancer;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClientConfigurationRegistrar;
+import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClients;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * An Autoconfiguration that loads default config for Spring Cloud LoadBalancer clients.
+ *
+ * @author Olga Maciaszek-Sharma
+ * @since 2.2.1
+ * @see EurekaLoadBalancerClientConfiguration
+ */
+@Configuration(proxyBeanMethods = false)
+@ConditionalOnClass(LoadBalancerClientConfigurationRegistrar.class)
+@LoadBalancerClients(defaultConfiguration = EurekaLoadBalancerClientConfiguration.class)
+public class LoadBalancerEurekaAutoConfiguration {
+
+}

spring-cloud-netflix-eureka-client/src/main/resources/META-INF/spring.factories

@@ -4,7 +4,8 @@ org.springframework.cloud.netflix.eureka.config.EurekaDiscoveryClientConfigServi
 org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration,\
 org.springframework.cloud.netflix.ribbon.eureka.RibbonEurekaAutoConfiguration,\
 org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration,\
-org.springframework.cloud.netflix.eureka.reactive.EurekaReactiveDiscoveryClientConfiguration
+org.springframework.cloud.netflix.eureka.reactive.EurekaReactiveDiscoveryClientConfiguration,\
+org.springframework.cloud.netflix.eureka.loadbalancer.LoadBalancerEurekaAutoConfiguration
 
 org.springframework.cloud.bootstrap.BootstrapConfiguration=\
 org.springframework.cloud.netflix.eureka.config.EurekaDiscoveryClientConfigServiceBootstrapConfiguration

spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/loadbalancer/EurekaLoadBalancerClientConfigurationTests.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2015-2019 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
+ *
+ *      https://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.loadbalancer;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.cloud.commons.util.InetUtils;
+import org.springframework.cloud.commons.util.InetUtilsProperties;
+import org.springframework.cloud.netflix.eureka.EurekaClientConfigBean;
+import org.springframework.cloud.netflix.eureka.EurekaInstanceConfigBean;
+import org.springframework.mock.env.MockEnvironment;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.netflix.eureka.loadbalancer.EurekaLoadBalancerClientConfiguration.APPROXIMATE_ZONE_FROM_HOSTNAME;
+import static org.springframework.cloud.netflix.eureka.loadbalancer.EurekaLoadBalancerClientConfiguration.LOADBALANCER_ZONE;
+
+/**
+ * Tests for {@link EurekaLoadBalancerClientConfiguration}.
+ *
+ * @author Olga Maciaszek-Sharma
+ */
+class EurekaLoadBalancerClientConfigurationTests {
+
+	private EurekaClientConfigBean eurekaClientConfig = new EurekaClientConfigBean();
+
+	private EurekaInstanceConfigBean eurekaInstanceConfig = new EurekaInstanceConfigBean(
+			new InetUtils(new InetUtilsProperties()));
+
+	private MockEnvironment environment = new MockEnvironment();
+
+	private EurekaLoadBalancerClientConfiguration preprocessor = new EurekaLoadBalancerClientConfiguration(
+			eurekaClientConfig, eurekaInstanceConfig, environment);
+
+	@Test
+	void shouldSetZoneFromInstanceMetadata() {
+		eurekaInstanceConfig.getMetadataMap().put("zone", "myZone");
+
+		preprocessor.preprocess();
+
+		assertThat(environment.getProperty(LOADBALANCER_ZONE)).isEqualTo("myZone");
+	}
+
+	@Test
+	public void shouldSetZoneToDefaultWhenNotSetInMetadata() {
+		preprocessor.preprocess();
+
+		assertThat(environment.getProperty(LOADBALANCER_ZONE)).isEqualTo("defaultZone");
+	}
+
+	@Test
+	public void shouldResolveApproximateZoneFromHost() {
+		eurekaInstanceConfig.setHostname("this.is.a.test.com");
+		environment.setProperty(APPROXIMATE_ZONE_FROM_HOSTNAME, "true");
+
+		preprocessor.preprocess();
+
+		assertThat(environment.getProperty(LOADBALANCER_ZONE)).isEqualTo("is.a.test.com");
+	}
+
+}