Use Ribbon by default. (#609)

* Use Ribbon by default.

* Fix after review.

* Reformat.

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

@@ -407,16 +407,19 @@ public class MyClass {
 ----
 
 The URI needs to use a virtual host name (that is, a service name, not a host name).
-The Ribbon client is used to create a full physical address.
+The Ribbon client or Spring Cloud LoadBalancer is used to create a full physical address.
 
 IMPORTANT: If you want to use a `@LoadBalanced WebClient.Builder`, you need to have a loadbalancer
 implementation in the classpath. It is recommended that you add the
 `org.springframework.cloud:spring-cloud-starter-loadbalancer` dependency to your project.
 Then, `ReactiveLoadBalancer` will be used underneath.
-Alternatively, this functionality will also work with spring-cloud-starter-netflix-ribbon, but the request
+Alternatively, this functionality will also work with `spring-cloud-starter-netflix-ribbon`, but the request
 will be handled by a non-reactive `LoadBalancerClient` under the hood. Additionally,
 spring-cloud-starter-netflix-ribbon is already in maintenance mode, so we do not recommend
 adding it to new projects.
+If you have both `spring-cloud-starter-loadbalancer` and `spring-cloud-starter-netflix-ribbon`
+in your classpath, Ribbon will be used by default. In order to switch to Spring Cloud LoadBalancer,
+set the value of `spring.cloud.loadbalancer.ribbon.enabled` to false.
 
 IMPORTANT: In order to make use of the more efficient cached version of `ServiceInstanceListSupplier`,
  `spring-cloud-starter-loadbalancer` will *enable caching* by default.
@@ -565,8 +568,14 @@ public class MyClass {
 ----
 
 The URI needs to use a virtual host name (that is, a service name, not a host name).
-The `ReactorLoadBalancerClient` is used to create a full physical address.
+The `ReactorLoadBalancer` is used to create a full physical address.
 
+NOTE: If you have `spring-cloud-netflix-ribbon` in your classpath, <<load-balancer-exchange-filter-function,`LoadBalancerExchangeFilterFunction`>>
+will be used by default to maintain backward compatibility. In order to be able to use
+`ReactorLoadBalancerExchangeFilterFunction`, set the value of `spring.cloud.loadbalancer.ribbon.enabled` property
+to `false`.
+
+[[load-balancer-exchange-filter-function]]
 ==== Spring WebFlux WebClient with non-reactive Load Balancer Client
 
 If you you don't have `org.springframework.cloud:spring-cloud-starter-loadbalancer` in your project,

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/reactive/ReactiveLoadBalancerAutoConfiguration.java

@@ -21,6 +21,7 @@ import java.util.List;
 
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -38,7 +39,8 @@ import org.springframework.web.reactive.function.client.WebClient;
 @Configuration
 @ConditionalOnClass(WebClient.class)
 @ConditionalOnBean(LoadBalancerClient.class)
-@ConditionalOnMissingBean(ReactiveLoadBalancer.Factory.class)
+@AutoConfigureAfter(ReactorLoadBalancerClientAutoConfiguration.class)
+@ConditionalOnMissingBean(ReactorLoadBalancerExchangeFilterFunction.class)
 @Deprecated
 public class ReactiveLoadBalancerAutoConfiguration {
 

spring-cloud-commons/src/main/java/org/springframework/cloud/client/loadbalancer/reactive/ReactorLoadBalancerClientAutoConfiguration.java

@@ -19,12 +19,21 @@ package org.springframework.cloud.client.loadbalancer.reactive;
 import java.util.Collections;
 import java.util.List;
 
+import javax.annotation.PostConstruct;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.cloud.client.loadbalancer.LoadBalanced;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.web.reactive.function.client.WebClient;
 
@@ -41,40 +50,92 @@ import org.springframework.web.reactive.function.client.WebClient;
 @ConditionalOnBean(ReactiveLoadBalancer.Factory.class)
 public class ReactorLoadBalancerClientAutoConfiguration {
 
-	private List<WebClient.Builder> webClientBuilders = Collections.emptyList();
-
-	List<WebClient.Builder> getBuilders() {
-		return this.webClientBuilders;
+	@Bean
+	@ConditionalOnClass(
+			name = "org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient")
+	public ReactorLoadBalancerClientRibbonWarnLogger reactorLoadBalancerClientRibbonWarnLogger() {
+		return new ReactorLoadBalancerClientRibbonWarnLogger();
 	}
 
-	@Bean
-	public SmartInitializingSingleton loadBalancedWebClientInitializer(
-			final List<WebClientCustomizer> customizers) {
-		return () -> {
-			for (WebClient.Builder webClientBuilder : getBuilders()) {
-				for (WebClientCustomizer customizer : customizers) {
-					customizer.customize(webClientBuilder);
+	@Configuration
+	@Conditional(OnNoRibbonDefaultCondition.class)
+	protected static class ReactorLoadBalancerExchangeFilterFunctionConfig {
+
+		private List<WebClient.Builder> webClientBuilders = Collections.emptyList();
+
+		List<WebClient.Builder> getBuilders() {
+			return this.webClientBuilders;
+		}
+
+		@Bean
+		public SmartInitializingSingleton loadBalancedWebClientInitializer(
+				final List<WebClientCustomizer> customizers) {
+			return () -> {
+				for (WebClient.Builder webClientBuilder : getBuilders()) {
+					for (WebClientCustomizer customizer : customizers) {
+						customizer.customize(webClientBuilder);
+					}
 				}
+			};
+		}
+
+		@Bean
+		public WebClientCustomizer loadBalancerClientWebClientCustomizer(
+				ReactorLoadBalancerExchangeFilterFunction filterFunction) {
+			return builder -> builder.filter(filterFunction);
+		}
+
+		@Bean
+		public ReactorLoadBalancerExchangeFilterFunction loadBalancerExchangeFilterFunction(
+				ReactiveLoadBalancer.Factory loadBalancerFactory) {
+			return new ReactorLoadBalancerExchangeFilterFunction(loadBalancerFactory);
+		}
+
+		@LoadBalanced
+		@Autowired(required = false)
+		void setWebClientBuilders(List<WebClient.Builder> webClientBuilders) {
+			this.webClientBuilders = webClientBuilders;
+		}
+
+	}
+
+	private static final class OnNoRibbonDefaultCondition extends AnyNestedCondition {
+
+		private OnNoRibbonDefaultCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@ConditionalOnProperty(value = "spring.cloud.loadbalancer.ribbon.enabled",
+				havingValue = "false")
+		static class RibbonNotEnabled {
+
+		}
+
+		@ConditionalOnMissingClass("org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient")
+		static class RibbonLoadBalancerNotPresent {
+
+		}
+
+	}
+
+	private static class ReactorLoadBalancerClientRibbonWarnLogger {
+
+		private static final Log LOG = LogFactory
+				.getLog(ReactorLoadBalancerClientRibbonWarnLogger.class);
+
+		@PostConstruct
+		void logWarning() {
+			if (LOG.isWarnEnabled()) {
+				LOG.warn("You have RibbonLoadBalancerClient on your classpath. "
+						+ "LoadBalancerExchangeFilterFunction that uses it under the "
+						+ "hood will be used by default. Spring Cloud Ribbon is now in maintenance mode, "
+						+ "so we suggest switching to "
+						+ ReactorLoadBalancerExchangeFilterFunction.class.getSimpleName()
+						+ " instead. In order to use it, set the value of `spring.cloud.loadbalancer.ribbon.enabled` to `false` or "
+						+ "remove spring-cloud-starter-netflix-ribbon from your project.");
 			}
-		};
-	}
+		}
 
-	@Bean
-	public WebClientCustomizer loadBalancerClientWebClientCustomizer(
-			ReactorLoadBalancerExchangeFilterFunction filterFunction) {
-		return builder -> builder.filter(filterFunction);
-	}
-
-	@Bean
-	public ReactorLoadBalancerExchangeFilterFunction loadBalancerExchangeFilterFunction(
-			ReactiveLoadBalancer.Factory loadBalancerFactory) {
-		return new ReactorLoadBalancerExchangeFilterFunction(loadBalancerFactory);
-	}
-
-	@LoadBalanced
-	@Autowired(required = false)
-	void setWebClientBuilders(List<WebClient.Builder> webClientBuilders) {
-		this.webClientBuilders = webClientBuilders;
 	}
 
 }

spring-cloud-commons/src/test/java/org/springframework/cloud/client/loadbalancer/reactive/ReactiveLoadBalancerAutoConfigurationTests.java

@@ -91,7 +91,7 @@ public class ReactiveLoadBalancerAutoConfigurationTests {
 	}
 
 	@Test
-	public void autoConfigurationNotLoadedWhenReactorLoadBalancerClientPresent() {
+	public void autoConfigurationNotLoadedWhenReactorLoadBalancerExchangeFilterFunctionPresent() {
 		ConfigurableApplicationContext context = init(
 				ReactorLoadBalancerClientPresent.class);
 		final Map<String, WebClient.Builder> webClientBuilders = context
@@ -139,6 +139,12 @@ public class ReactiveLoadBalancerAutoConfigurationTests {
 			return serviceId -> new TestReactiveLoadBalancer();
 		}
 
+		@Bean
+		ReactorLoadBalancerExchangeFilterFunction reactorLoadBalancerExchangeFilterFunction() {
+			return new ReactorLoadBalancerExchangeFilterFunction(
+					reactiveLoadBalancerFactory());
+		}
+
 	}
 
 	@Configuration

spring-cloud-loadbalancer/src/main/java/org/springframework/cloud/loadbalancer/config/BlockingLoadBalancerClientAutoConfiguration.java

@@ -55,8 +55,8 @@ public class BlockingLoadBalancerClientAutoConfiguration {
 	@Bean
 	@ConditionalOnClass(
 			name = "org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient")
-	public RibbonWarnLogger ribbonWarnLogger() {
-		return new RibbonWarnLogger();
+	public BlockingLoadBalancerClientRibbonWarnLogger blockingLoadBalancerClientRibbonWarnLogger() {
+		return new BlockingLoadBalancerClientRibbonWarnLogger();
 	}
 
 	@Configuration
@@ -93,17 +93,19 @@ public class BlockingLoadBalancerClientAutoConfiguration {
 
 	}
 
-	static class RibbonWarnLogger {
+	static class BlockingLoadBalancerClientRibbonWarnLogger {
 
-		private static final Log LOG = LogFactory.getLog(RibbonWarnLogger.class);
+		private static final Log LOG = LogFactory
+				.getLog(BlockingLoadBalancerClientRibbonWarnLogger.class);
 
 		@PostConstruct
 		void logWarning() {
 			if (LOG.isWarnEnabled()) {
 				LOG.warn(
-						"You already have RibbonLoadBalancerClient on your classpath. It will be used by default. To use "
+						"You already have RibbonLoadBalancerClient on your classpath. It will be used by default. "
+								+ "As Spring Cloud Ribbon is in maintenance mode. We recommend switching to "
 								+ BlockingLoadBalancerClient.class.getSimpleName()
-								+ " set the value of `spring.cloud.loadbalancer.ribbon.enabled` to `false` or "
+								+ " instead. In order to use it, set the value of `spring.cloud.loadbalancer.ribbon.enabled` to `false` or "
 								+ "remove spring-cloud-starter-netflix-ribbon from your project.");
 			}
 		}

spring-cloud-loadbalancer/src/test/java/org/springframework/cloud/loadbalancer/config/BlockingLoadBalancerClientAutoConfigurationTests.java

@@ -22,7 +22,7 @@ import org.springframework.boot.autoconfigure.AutoConfigurations;
 import org.springframework.boot.test.context.FilteredClassLoader;
 import org.springframework.boot.test.context.runner.ApplicationContextRunner;
 import org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient;
-import org.springframework.cloud.loadbalancer.config.BlockingLoadBalancerClientAutoConfiguration.RibbonWarnLogger;
+import org.springframework.cloud.loadbalancer.config.BlockingLoadBalancerClientAutoConfiguration.BlockingLoadBalancerClientRibbonWarnLogger;
 import org.springframework.web.client.RestTemplate;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -44,7 +44,8 @@ public class BlockingLoadBalancerClientAutoConfigurationTests {
 	public void beansCreatedNormally() {
 		applicationContextRunner.run(ctxt -> {
 			assertThat(ctxt).hasSingleBean(BlockingLoadBalancerClient.class);
-			assertThat(ctxt).doesNotHaveBean(RibbonWarnLogger.class);
+			assertThat(ctxt)
+					.doesNotHaveBean(BlockingLoadBalancerClientRibbonWarnLogger.class);
 		});
 	}
 
@@ -54,7 +55,8 @@ public class BlockingLoadBalancerClientAutoConfigurationTests {
 				.withClassLoader(new FilteredClassLoader(RestTemplate.class))
 				.run(context -> {
 					assertThat(context).doesNotHaveBean(BlockingLoadBalancerClient.class);
-					assertThat(context).doesNotHaveBean(RibbonWarnLogger.class);
+					assertThat(context).doesNotHaveBean(
+							BlockingLoadBalancerClientRibbonWarnLogger.class);
 				});
 	}