Allow customising HC5 RequestConfig in EurekaClientHttpRequestFactorySupplier

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

@@ -116,6 +116,8 @@ eureka:
       socket-timeout: 10000
 ----
 
+You can also customise the `RequestConfig` for the underlying Apache HC5 client by creating a bean of type `EurekaClientHttpRequestFactorySupplier.RequestConfigCustomizer`.
+
 === Status Page and Health Indicator
 
 The status page and health indicators for a Eureka instance default to `/info` and `/health` respectively, which are the default locations of useful endpoints in a Spring Boot Actuator application.

spring-cloud-netflix-eureka-client-tls-tests/src/test/java/org/springframework/cloud/netflix/eureka/EurekaClientTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2024 the original author or authors.
+ * Copyright 2018-2025 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.netflix.eureka;
 
+import java.util.Collections;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.junit.jupiter.api.BeforeAll;
@@ -64,8 +66,8 @@ public RestTemplateTransportClientFactories forceRestTemplateTransportClientFact
 
 		@Bean
 		public RestTemplateDiscoveryClientOptionalArgs discoveryClientOptionalArgs() {
-			return new RestTemplateDiscoveryClientOptionalArgs(
-					new DefaultEurekaClientHttpRequestFactorySupplier(new RestTemplateTimeoutProperties()), null);
+			return new RestTemplateDiscoveryClientOptionalArgs(new DefaultEurekaClientHttpRequestFactorySupplier(
+					new RestTemplateTimeoutProperties(), Collections.emptySet()));
 		}
 
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2024 the original author or authors.
+ * Copyright 2017-2025 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.
@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 import java.security.GeneralSecurityException;
+import java.util.Set;
 
 import com.netflix.discovery.AbstractDiscoveryClientOptionalArgs;
 import com.netflix.discovery.shared.transport.jersey.TransportClientFactories;
@@ -94,8 +95,10 @@ static class RestTemplateConfiguration {
 		@Bean
 		@ConditionalOnMissingBean
 		EurekaClientHttpRequestFactorySupplier defaultEurekaClientHttpRequestFactorySupplier(
-				RestTemplateTimeoutProperties restTemplateTimeoutProperties) {
-			return new DefaultEurekaClientHttpRequestFactorySupplier(restTemplateTimeoutProperties);
+				RestTemplateTimeoutProperties restTemplateTimeoutProperties,
+				Set<EurekaClientHttpRequestFactorySupplier.RequestConfigCustomizer> requestConfigCustomizers) {
+			return new DefaultEurekaClientHttpRequestFactorySupplier(restTemplateTimeoutProperties,
+					requestConfigCustomizers);
 		}
 
 		@Bean
@@ -189,8 +192,10 @@ protected static class RestClientConfiguration {
 		@Bean
 		@ConditionalOnMissingBean
 		EurekaClientHttpRequestFactorySupplier defaultEurekaClientHttpRequestFactorySupplier(
-				RestClientTimeoutProperties restClientTimeoutProperties) {
-			return new DefaultEurekaClientHttpRequestFactorySupplier(restClientTimeoutProperties);
+				RestClientTimeoutProperties restClientTimeoutProperties,
+				Set<EurekaClientHttpRequestFactorySupplier.RequestConfigCustomizer> requestConfigCustomizers) {
+			return new DefaultEurekaClientHttpRequestFactorySupplier(restClientTimeoutProperties,
+					requestConfigCustomizers);
 		}
 
 		@Bean

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2024 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.netflix.eureka.config;
 
+import java.util.Set;
+
 import com.netflix.discovery.EurekaClientConfig;
 import com.netflix.discovery.shared.transport.EurekaHttpClient;
 
@@ -54,7 +56,7 @@
 import org.springframework.web.reactive.function.client.WebClient;
 
 /**
- * Bootstrap configuration for config client that wants to lookup the config server via
+ * Bootstrap configuration for config client that wants to look the config server up via
  * discovery.
  *
  * @author Dave Syer
@@ -103,8 +105,10 @@ public RestTemplateEurekaHttpClient configDiscoveryRestTemplateEurekaHttpClient(
 		@Bean
 		@ConditionalOnMissingBean
 		EurekaClientHttpRequestFactorySupplier defaultEurekaClientHttpRequestFactorySupplier(
-				RestTemplateTimeoutProperties restTemplateTimeoutProperties) {
-			return new DefaultEurekaClientHttpRequestFactorySupplier(restTemplateTimeoutProperties);
+				RestTemplateTimeoutProperties restTemplateTimeoutProperties,
+				Set<EurekaClientHttpRequestFactorySupplier.RequestConfigCustomizer> requestConfigCustomizers) {
+			return new DefaultEurekaClientHttpRequestFactorySupplier(restTemplateTimeoutProperties,
+					requestConfigCustomizers);
 		}
 
 		/**
@@ -174,8 +178,10 @@ public RestClientEurekaHttpClient configDiscoveryRestClientEurekaHttpClient(Eure
 		@Bean
 		@ConditionalOnMissingBean
 		EurekaClientHttpRequestFactorySupplier defaultEurekaClientHttpRequestFactorySupplier(
-				RestClientTimeoutProperties restClientTimeoutProperties) {
-			return new DefaultEurekaClientHttpRequestFactorySupplier(restClientTimeoutProperties);
+				RestClientTimeoutProperties restClientTimeoutProperties,
+				Set<EurekaClientHttpRequestFactorySupplier.RequestConfigCustomizer> requestConfigCustomizers) {
+			return new DefaultEurekaClientHttpRequestFactorySupplier(restClientTimeoutProperties,
+					requestConfigCustomizers);
 		}
 
 		static class OnRestClientPresentAndEnabledCondition extends AllNestedConditions {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2024 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -61,7 +61,8 @@ public void initialize(BootstrapRegistry registry) {
 			EurekaHttpClient httpClient = new RestClientTransportClientFactory(
 					context.getOrElse(TlsProperties.class, null),
 					context.getOrElse(EurekaClientHttpRequestFactorySupplier.class,
-							new DefaultEurekaClientHttpRequestFactorySupplier(new RestClientTimeoutProperties())))
+							new DefaultEurekaClientHttpRequestFactorySupplier(new RestClientTimeoutProperties(),
+									Collections.emptySet())))
 				.newClient(HostnameBasedUrlRandomizer.randomEndpoint(config, getPropertyResolver(context)));
 			return new EurekaConfigServerInstanceProvider(httpClient, config)::getInstances;
 		});

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/http/DefaultEurekaClientHttpRequestFactorySupplier.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2024 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -16,11 +16,14 @@
 
 package org.springframework.cloud.netflix.eureka.http;
 
+import java.util.Collections;
+import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
+import org.apache.hc.client5.http.config.ConnectionConfig;
 import org.apache.hc.client5.http.config.RequestConfig;
 import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
 import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
@@ -50,9 +53,12 @@ public class DefaultEurekaClientHttpRequestFactorySupplier implements EurekaClie
 
 	private final TimeoutProperties timeoutProperties;
 
+	// TODO: switch to final after removing deprecated interfaces
+	private Set<RequestConfigCustomizer> requestConfigCustomizers = Collections.emptySet();
+
 	/**
 	 * @deprecated in favour of
-	 * {@link DefaultEurekaClientHttpRequestFactorySupplier#DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties)}
+	 * {@link DefaultEurekaClientHttpRequestFactorySupplier#DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties, Set)}
 	 */
 	@Deprecated(forRemoval = true)
 	public DefaultEurekaClientHttpRequestFactorySupplier() {
@@ -61,27 +67,36 @@ public DefaultEurekaClientHttpRequestFactorySupplier() {
 
 	/**
 	 * @deprecated in favour of
-	 * {@link DefaultEurekaClientHttpRequestFactorySupplier#DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties)}
+	 * {@link DefaultEurekaClientHttpRequestFactorySupplier#DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties, Set)}
 	 */
 	@Deprecated(forRemoval = true)
 	public DefaultEurekaClientHttpRequestFactorySupplier(RestTemplateTimeoutProperties timeoutProperties) {
 		this.timeoutProperties = timeoutProperties;
 	}
 
+	/**
+	 * @deprecated in favour of
+	 * {@link DefaultEurekaClientHttpRequestFactorySupplier#DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties, Set)}
+	 */
+	@Deprecated(forRemoval = true)
 	public DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties timeoutProperties) {
 		this.timeoutProperties = timeoutProperties;
 	}
 
+	public DefaultEurekaClientHttpRequestFactorySupplier(TimeoutProperties timeoutProperties,
+			Set<RequestConfigCustomizer> requestConfigCustomizers) {
+		this.timeoutProperties = timeoutProperties;
+		this.requestConfigCustomizers = requestConfigCustomizers;
+	}
+
 	@Override
 	public ClientHttpRequestFactory get(SSLContext sslContext, @Nullable HostnameVerifier hostnameVerifier) {
 		HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
 		if (sslContext != null || hostnameVerifier != null || timeoutProperties != null) {
 			httpClientBuilder
 				.setConnectionManager(buildConnectionManager(sslContext, hostnameVerifier, timeoutProperties));
 		}
-		if (timeoutProperties != null) {
-			httpClientBuilder.setDefaultRequestConfig(buildRequestConfig());
-		}
+		httpClientBuilder.setDefaultRequestConfig(buildRequestConfig());
 
 		CloseableHttpClient httpClient = httpClientBuilder.build();
 		HttpComponentsClientHttpRequestFactory requestFactory = new HttpComponentsClientHttpRequestFactory();
@@ -90,7 +105,7 @@ public ClientHttpRequestFactory get(SSLContext sslContext, @Nullable HostnameVer
 	}
 
 	private HttpClientConnectionManager buildConnectionManager(SSLContext sslContext, HostnameVerifier hostnameVerifier,
-			TimeoutProperties restTemplateTimeoutProperties) {
+			TimeoutProperties timeoutProperties) {
 		PoolingHttpClientConnectionManagerBuilder connectionManagerBuilder = PoolingHttpClientConnectionManagerBuilder
 			.create();
 		SSLConnectionSocketFactoryBuilder sslConnectionSocketFactoryBuilder = SSLConnectionSocketFactoryBuilder
@@ -102,20 +117,25 @@ private HttpClientConnectionManager buildConnectionManager(SSLContext sslContext
 			sslConnectionSocketFactoryBuilder.setHostnameVerifier(hostnameVerifier);
 		}
 		connectionManagerBuilder.setSSLSocketFactory(sslConnectionSocketFactoryBuilder.build());
-		if (restTemplateTimeoutProperties != null) {
+		if (timeoutProperties != null) {
 			connectionManagerBuilder.setDefaultSocketConfig(SocketConfig.custom()
-				.setSoTimeout(Timeout.of(restTemplateTimeoutProperties.getSocketTimeout(), TimeUnit.MILLISECONDS))
+				.setSoTimeout(Timeout.of(timeoutProperties.getSocketTimeout(), TimeUnit.MILLISECONDS))
+				.build());
+			connectionManagerBuilder.setDefaultConnectionConfig(ConnectionConfig.custom()
+				.setConnectTimeout(Timeout.of(timeoutProperties.getConnectTimeout(), TimeUnit.MILLISECONDS))
 				.build());
 		}
 		return connectionManagerBuilder.build();
 	}
 
 	private RequestConfig buildRequestConfig() {
-		return RequestConfig.custom()
-			.setConnectTimeout(Timeout.of(timeoutProperties.getConnectTimeout(), TimeUnit.MILLISECONDS))
-			.setConnectionRequestTimeout(
-					Timeout.of(timeoutProperties.getConnectRequestTimeout(), TimeUnit.MILLISECONDS))
-			.build();
+		RequestConfig.Builder requestConfigBuilder = RequestConfig.custom();
+		if (timeoutProperties != null) {
+			requestConfigBuilder.setConnectionRequestTimeout(
+					Timeout.of(timeoutProperties.getConnectRequestTimeout(), TimeUnit.MILLISECONDS));
+		}
+		requestConfigCustomizers.forEach(customizer -> customizer.customize(requestConfigBuilder));
+		return requestConfigBuilder.build();
 	}
 
 }

spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/http/EurekaClientHttpRequestFactorySupplier.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2022 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -19,6 +19,8 @@
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 
+import org.apache.hc.client5.http.config.RequestConfig;
+
 import org.springframework.http.client.ClientHttpRequestFactory;
 import org.springframework.lang.Nullable;
 
@@ -38,4 +40,16 @@ public interface EurekaClientHttpRequestFactorySupplier {
 	 */
 	ClientHttpRequestFactory get(SSLContext sslContext, @Nullable HostnameVerifier hostnameVerifier);
 
+	/**
+	 * Allows customising the {@link RequestConfig} of the underlying Apache HC5 instance.
+	 *
+	 * @since 4.2.1
+	 */
+	@FunctionalInterface
+	interface RequestConfigCustomizer {
+
+		void customize(RequestConfig.Builder builder);
+
+	}
+
 }

spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/http/EurekaServerMockApplication.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2022 the original author or authors.
+ * Copyright 2017-2025 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.
@@ -31,6 +31,7 @@
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
@@ -45,6 +46,7 @@
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.PutMapping;
 import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseStatus;
@@ -59,6 +61,7 @@
  *
  * @author Daniel Lavoie
  * @author Wonchul Heo
+ * @author Olga Maciaszek-Sharma
  */
 @Configuration(proxyBeanMethods = false)
 @RestController
@@ -172,7 +175,11 @@ public Applications getApplications(@PathVariable(required = false) String addre
 	}
 
 	@GetMapping("/apps/{appName}")
-	public Application getApplication(@PathVariable String appName) {
+	public Application getApplication(@PathVariable String appName, @RequestHeader HttpHeaders headers) {
+		// Used to verify that RequestConfig customizer has taken effect
+		if (appName.equals("upgrade") && !headers.containsKey("upgrade")) {
+			throw new RuntimeException("No upgrade header found");
+		}
 		return new Application();
 	}