Support Spring RestClient as default TransportClientFactory (#4281)

docs/modules/ROOT/pages/spring-cloud-netflix.adoc

@@ -270,9 +270,11 @@ It is initialized in a `SmartLifecycle` (with `phase=0`), so the earliest you ca
 
 ==== Underlying HTTP clients
 
-`EurekaClient` uses either `RestTemplate`, `WebClient` or `JerseyClient` under the hood. In order to use the `EurekaClient`, you need to have one of the supported HTTP clients on your classpath.
+`EurekaClient` uses either `RestClient`, `RestTemplate`, `WebClient` or `JerseyClient` under the hood. In order to use the `EurekaClient`, you need to have one of the supported HTTP clients on your classpath.
 
-To use `RestTemplate`, add `spring-boot-starter-web` to your dependencies. To use `WebClient`, add `spring-boot-starter-webflux` to your dependencies. If both `RestTemplate` and `WebClient` are on the classpath when `eureka.client.webclient.enabled` is set to `true`, `WebClient` is used. Otherwise, `RestTemplate` is used.
+To use `RestTemplate` or `RestClient`, add `spring-boot-starter-web` to your dependencies. To use `WebClient`, add `spring-boot-starter-webflux` to your dependencies. If both `spring-boot-starter-web` and `spring-boot-starter-webflux` are included in the dependencies and the `eureka.client.webclient.enabled` flag is set to `true`, then `WebClient` will be used. If that's not the case and `eureka.client.restclient.enabled` is set to false, the `RestTemplate` will be used. Otherwise, the `RestClient` will be used.
+
+NOTE: Starting from 4.2.0, the default client has changed to `RestClient`.
 
 If you wish to use Jersey instead, you need to add the Jersey dependencies to your classpath.
 The following example shows the dependencies you need to add:

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/config/DiscoveryClientOptionalArgsConfiguration.java

@@ -25,7 +25,6 @@
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.beans.factory.ObjectProvider;
-import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.AllNestedConditions;
 import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
@@ -42,19 +41,23 @@
 import org.springframework.cloud.netflix.eureka.RestTemplateTimeoutProperties;
 import org.springframework.cloud.netflix.eureka.http.DefaultEurekaClientHttpRequestFactorySupplier;
 import org.springframework.cloud.netflix.eureka.http.EurekaClientHttpRequestFactorySupplier;
+import org.springframework.cloud.netflix.eureka.http.RestClientDiscoveryClientOptionalArgs;
+import org.springframework.cloud.netflix.eureka.http.RestClientTransportClientFactories;
 import org.springframework.cloud.netflix.eureka.http.RestTemplateDiscoveryClientOptionalArgs;
 import org.springframework.cloud.netflix.eureka.http.RestTemplateTransportClientFactories;
 import org.springframework.cloud.netflix.eureka.http.WebClientDiscoveryClientOptionalArgs;
 import org.springframework.cloud.netflix.eureka.http.WebClientTransportClientFactories;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.reactive.function.client.WebClient;
 
 /**
  * @author Daniel Lavoie
  * @author Armin Krezovic
  * @author Olga Maciaszek-Sharma
+ * @author Wonchul Heo
  */
 @Configuration(proxyBeanMethods = false)
 @EnableConfigurationProperties(RestTemplateTimeoutProperties.class)
@@ -70,14 +73,14 @@ public TlsProperties tlsProperties() {
 
 	@Bean
 	@ConditionalOnClass(name = "org.springframework.web.client.RestTemplate")
-	@Conditional(JerseyClientNotPresentOrNotEnabledCondition.class)
+	@Conditional(RestTemplateEnabledCondition.class)
 	@ConditionalOnMissingBean(value = { AbstractDiscoveryClientOptionalArgs.class }, search = SearchStrategy.CURRENT)
-	@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
-			havingValue = "false")
 	public RestTemplateDiscoveryClientOptionalArgs restTemplateDiscoveryClientOptionalArgs(TlsProperties tlsProperties,
 			EurekaClientHttpRequestFactorySupplier eurekaClientHttpRequestFactorySupplier,
 			ObjectProvider<RestTemplateBuilder> restTemplateBuilders) throws GeneralSecurityException, IOException {
-		logger.info("Eureka HTTP Client uses RestTemplate.");
+		if (logger.isInfoEnabled()) {
+			logger.info("Eureka HTTP Client uses RestTemplate.");
+		}
 		RestTemplateDiscoveryClientOptionalArgs result = new RestTemplateDiscoveryClientOptionalArgs(
 				eurekaClientHttpRequestFactorySupplier, restTemplateBuilders::getIfAvailable);
 		setupTLS(result, tlsProperties);
@@ -86,10 +89,8 @@ public RestTemplateDiscoveryClientOptionalArgs restTemplateDiscoveryClientOption
 
 	@Bean
 	@ConditionalOnClass(name = "org.springframework.web.client.RestTemplate")
-	@Conditional(JerseyClientNotPresentOrNotEnabledCondition.class)
+	@Conditional(RestTemplateEnabledCondition.class)
 	@ConditionalOnMissingBean(value = { TransportClientFactories.class }, search = SearchStrategy.CURRENT)
-	@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
-			havingValue = "false")
 	public RestTemplateTransportClientFactories restTemplateTransportClientFactories(
 			RestTemplateDiscoveryClientOptionalArgs optionalArgs) {
 		return new RestTemplateTransportClientFactories(optionalArgs);
@@ -118,7 +119,9 @@ static class DiscoveryClientOptionalArgsTlsConfiguration {
 
 		DiscoveryClientOptionalArgsTlsConfiguration(TlsProperties tlsProperties,
 				AbstractDiscoveryClientOptionalArgs optionalArgs) throws GeneralSecurityException, IOException {
-			logger.info("Eureka HTTP Client uses Jersey");
+			if (logger.isInfoEnabled()) {
+				logger.info("Eureka HTTP Client uses Jersey");
+			}
 			setupTLS(optionalArgs, tlsProperties);
 		}
 
@@ -129,16 +132,15 @@ static class DiscoveryClientOptionalArgsTlsConfiguration {
 	@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", havingValue = "true")
 	protected static class WebClientConfiguration {
 
-		@Autowired
-		private TlsProperties tlsProperties;
-
 		@Bean
 		@ConditionalOnMissingBean(
 				value = { AbstractDiscoveryClientOptionalArgs.class, RestTemplateDiscoveryClientOptionalArgs.class },
 				search = SearchStrategy.CURRENT)
-		public WebClientDiscoveryClientOptionalArgs webClientDiscoveryClientOptionalArgs(
+		public WebClientDiscoveryClientOptionalArgs webClientDiscoveryClientOptionalArgs(TlsProperties tlsProperties,
 				ObjectProvider<WebClient.Builder> builder) throws GeneralSecurityException, IOException {
-			logger.info("Eureka HTTP Client uses WebClient.");
+			if (logger.isInfoEnabled()) {
+				logger.info("Eureka HTTP Client uses WebClient.");
+			}
 			WebClientDiscoveryClientOptionalArgs result = new WebClientDiscoveryClientOptionalArgs(
 					builder::getIfAvailable);
 			setupTLS(result, tlsProperties);
@@ -168,6 +170,33 @@ public WebClientNotFoundConfiguration() {
 
 	}
 
+	@ConditionalOnClass(name = "org.springframework.web.client.RestClient")
+	@Conditional(RestClientEnabledCondition.class)
+	protected static class RestClientConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(value = { AbstractDiscoveryClientOptionalArgs.class },
+				search = SearchStrategy.CURRENT)
+		public RestClientDiscoveryClientOptionalArgs restClientDiscoveryClientOptionalArgs(TlsProperties tlsProperties,
+				ObjectProvider<RestClient.Builder> builder) throws GeneralSecurityException, IOException {
+			if (logger.isInfoEnabled()) {
+				logger.info("Eureka HTTP Client uses RestClient.");
+			}
+			RestClientDiscoveryClientOptionalArgs result = new RestClientDiscoveryClientOptionalArgs(
+					builder::getIfAvailable);
+			setupTLS(result, tlsProperties);
+			return result;
+		}
+
+		@Bean
+		@ConditionalOnMissingBean(value = TransportClientFactories.class, search = SearchStrategy.CURRENT)
+		public RestClientTransportClientFactories restClientTransportClientFactories(
+				ObjectProvider<RestClient.Builder> builder) {
+			return new RestClientTransportClientFactories(builder::getIfAvailable);
+		}
+
+	}
+
 	static class JerseyClientPresentAndEnabledCondition extends AllNestedConditions {
 
 		JerseyClientPresentAndEnabledCondition() {
@@ -204,4 +233,53 @@ static class OnJerseyClientDisabled {
 
 	}
 
+	static class RestTemplateEnabledCondition extends AllNestedConditions {
+
+		RestTemplateEnabledCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@Conditional(JerseyClientNotPresentOrNotEnabledCondition.class)
+		static class OnJerseyClientNotPresentOrNotEnabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
+				havingValue = "false")
+		static class OnWebClientDisabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "restclient.enabled", havingValue = "false")
+		static class OnRestClientDisabled {
+
+		}
+
+	}
+
+	static class RestClientEnabledCondition extends AllNestedConditions {
+
+		RestClientEnabledCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@Conditional(JerseyClientNotPresentOrNotEnabledCondition.class)
+		static class OnJerseyClientNotPresentOrNotEnabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
+				havingValue = "false")
+		static class OnWebClientDisabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "restclient.enabled", matchIfMissing = true,
+				havingValue = "true")
+		static class OnRestClientDisabled {
+
+		}
+
+	}
+
 }

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/config/EurekaConfigServerBootstrapConfiguration.java

@@ -27,6 +27,7 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.boot.autoconfigure.condition.SearchStrategy;
 import org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration;
+import org.springframework.boot.autoconfigure.web.client.RestClientAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.web.client.RestTemplateBuilder;
@@ -37,6 +38,8 @@
 import org.springframework.cloud.netflix.eureka.RestTemplateTimeoutProperties;
 import org.springframework.cloud.netflix.eureka.http.DefaultEurekaClientHttpRequestFactorySupplier;
 import org.springframework.cloud.netflix.eureka.http.EurekaClientHttpRequestFactorySupplier;
+import org.springframework.cloud.netflix.eureka.http.RestClientEurekaHttpClient;
+import org.springframework.cloud.netflix.eureka.http.RestClientTransportClientFactory;
 import org.springframework.cloud.netflix.eureka.http.RestTemplateEurekaHttpClient;
 import org.springframework.cloud.netflix.eureka.http.RestTemplateTransportClientFactory;
 import org.springframework.cloud.netflix.eureka.http.WebClientEurekaHttpClient;
@@ -46,6 +49,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
 import org.springframework.lang.Nullable;
+import org.springframework.web.client.RestClient;
 import org.springframework.web.reactive.function.client.WebClient;
 
 /**
@@ -54,6 +58,7 @@
  *
  * @author Dave Syer
  * @author Armin Krezovic
+ * @author Wonchul Heo
  */
 @ConditionalOnClass(ConfigServicePropertySourceLocator.class)
 @Conditional(EurekaConfigServerBootstrapConfiguration.EurekaConfigServerBootstrapCondition.class)
@@ -69,8 +74,7 @@ public EurekaClientConfigBean eurekaClientConfigBean() {
 
 	@Bean
 	@ConditionalOnMissingBean(EurekaHttpClient.class)
-	@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
-			havingValue = "false")
+	@Conditional(RestTemplateEnabledCondition.class)
 	public RestTemplateEurekaHttpClient configDiscoveryRestTemplateEurekaHttpClient(EurekaClientConfigBean config,
 			Environment env, @Nullable TlsProperties properties,
 			EurekaClientHttpRequestFactorySupplier eurekaClientHttpRequestFactorySupplier,
@@ -109,6 +113,61 @@ public WebClientEurekaHttpClient configDiscoveryWebClientEurekaHttpClient(Eureka
 
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@ConditionalOnClass(name = "org.springframework.web.client.RestClient")
+	@Conditional(RestClientEnabledCondition.class)
+	@ImportAutoConfiguration(RestClientAutoConfiguration.class)
+	protected static class RestClientConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean(EurekaHttpClient.class)
+		public RestClientEurekaHttpClient configDiscoveryRestClientEurekaHttpClient(EurekaClientConfigBean config,
+				ObjectProvider<RestClient.Builder> builder, Environment env) {
+			return (RestClientEurekaHttpClient) new RestClientTransportClientFactory(builder::getIfAvailable)
+				.newClient(HostnameBasedUrlRandomizer.randomEndpoint(config, env));
+		}
+
+	}
+
+	static class RestTemplateEnabledCondition extends AllNestedConditions {
+
+		RestTemplateEnabledCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
+				havingValue = "false")
+		static class OnWebClientDisabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "restclient.enabled", havingValue = "false")
+		static class OnRestClientDisabled {
+
+		}
+
+	}
+
+	static class RestClientEnabledCondition extends AllNestedConditions {
+
+		RestClientEnabledCondition() {
+			super(ConfigurationPhase.REGISTER_BEAN);
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "webclient.enabled", matchIfMissing = true,
+				havingValue = "false")
+		static class OnWebClientDisabled {
+
+		}
+
+		@ConditionalOnProperty(prefix = "eureka.client", name = "restclient.enabled", matchIfMissing = true,
+				havingValue = "true")
+		static class OnRestClientDisabled {
+
+		}
+
+	}
+
 	static class EurekaConfigServerBootstrapCondition extends AllNestedConditions {
 
 		EurekaConfigServerBootstrapCondition() {