Allow Customizer for HttpClientConnectionManager in HttpClient5FeignConfiguration

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

@@ -144,14 +144,13 @@ When it comes to the Apache HttpClient 5-backed Feign clients, it's enough to en
 You can customize the HTTP client used by providing a bean of either `org.apache.hc.client5.http.impl.classic.CloseableHttpClient` when using Apache HC5.
 
 You can further customise http clients by setting values in the `spring.cloud.openfeign.httpclient.xxx` properties. The ones prefixed just with `httpclient` will work for all the clients, the ones prefixed with `httpclient.hc5` to Apache HttpClient 5, and the ones prefixed with `httpclient.http2` to Http2Client. You can find a full list of properties you can customise in the appendix.
-If you can not configure Apache HttpClient 5 by using properties, there is an `HttpClient5FeignConfiguration.HttpClientBuilderCustomizer` interface for programmatic configuration.
+If you can not configure Apache HttpClient 5 by using properties, there is an `HttpClient5FeignConfiguration.HttpClientBuilderCustomizer` interface for programmatic configuration. Similarly, to configure the `HttpClientConnectionManager`, you can use `HttpClient5FeignConfiguration.HttpClientConnectionManagerBuilderCustomizer`. Both usages are shown in the example below.
 
 TIP: Apache HTTP Components `5.4` have changed defaults in the HttpClient relating to HTTP/1.1 TLS upgrades. Most proxy servers handle upgrades without issue, however, you may encounter issues with Envoy or Istio. If you need to restore previous behaviour, you can use `HttpClient5FeignConfiguration.HttpClientBuilderCustomizer` to do it, as shown in the example below.
 
 [source,java,indent=0]
 ----
-@Configuration
-public class FooConfiguration {
+public class HttpClientConfiguration {
 
 	@Bean
 	public HttpClient5FeignConfiguration.HttpClientBuilderCustomizer httpClientBuilder() {
@@ -164,6 +163,24 @@ public class FooConfiguration {
 }
 ----
 
+TIP: Apache HTTP Components `5.5.1` have changed defaults in the HttpClient relating to TLS handshake timeouts. An unset TLS handshake timeout is now implicitly bound by the `connectTimeout` while it was unbounded previously. To restore previous defaults, you can use `HttpClient5FeignConfiguration.HttpClientBuilderCustomizer` to do it, as shown in the example below.
+
+[source,java,indent=0]
+----
+public class HttpClientConnectionManagerConfiguration {
+
+	@Bean
+	public HttpClient5FeignConfiguration.HttpClientConnectionManagerBuilderCustomizer httpClientConnectionManagerBuilder() {
+		return (httpClientConnectionManagerBuilder) -> {
+			TlsConfig.Builder tlsConfigBuilder = TlsConfig.custom();
+			// 0 seconds timeout means infinite
+            tlsConfigBuilder.setHandshakeTimeout(Timeout.of(0, TimeUnit.SECONDS));
+            httpClientConnectionManagerBuilder.setDefaultTlsConfig(tlsConfigBuilder.build());
+		};
+	}
+}
+----
+
 TIP: Starting with Spring Cloud OpenFeign 4, the Feign Apache HttpClient 4 is no longer supported. We suggest using Apache HttpClient 5 instead.
 
 Spring Cloud OpenFeign _does not_ provide the following beans by default for feign, but still looks up beans of these types from the application context to create the Feign client:

spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/clientconfig/HttpClient5FeignConfiguration.java

@@ -71,8 +71,9 @@ public class HttpClient5FeignConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean(HttpClientConnectionManager.class)
-	public HttpClientConnectionManager hc5ConnectionManager(FeignHttpClientProperties httpClientProperties) {
-		return PoolingHttpClientConnectionManagerBuilder.create()
+	public HttpClientConnectionManager hc5ConnectionManager(FeignHttpClientProperties httpClientProperties,
+			ObjectProvider<List<HttpClientConnectionManagerBuilderCustomizer>> customizerProvider) {
+		PoolingHttpClientConnectionManagerBuilder httpClientConnectionManager =  PoolingHttpClientConnectionManagerBuilder.create()
 			.setSSLSocketFactory(httpsSSLConnectionSocketFactory(httpClientProperties.isDisableSslValidation()))
 			.setMaxConnTotal(httpClientProperties.getMaxConnections())
 			.setMaxConnPerRoute(httpClientProperties.getMaxConnectionsPerRoute())
@@ -84,8 +85,11 @@ public HttpClientConnectionManager hc5ConnectionManager(FeignHttpClientPropertie
 			.setDefaultSocketConfig(SocketConfig.custom()
 				.setSoTimeout(Timeout.of(httpClientProperties.getHc5().getSocketTimeout(),
 						httpClientProperties.getHc5().getSocketTimeoutUnit()))
-				.build())
-			.build();
+				.build());
+
+		customizerProvider.getIfAvailable(List::of).forEach(c -> c.customize(httpClientConnectionManager));
+
+		return httpClientConnectionManager.build();
 	}
 
 	@Bean
@@ -174,4 +178,21 @@ public interface HttpClientBuilderCustomizer {
 
 	}
 
+	/**
+	 * Callback interface that customize {@link HttpClientBuilder} objects before
+	 * HttpClientConnectionManager created.
+	 *
+	 * @author Severin Kistler
+	 * @since 5.1.0
+	 */
+	public interface HttpClientConnectionManagerBuilderCustomizer {
+
+		/**
+		 * Customize PoolingHttpClientConnectionManagerBuilder.
+		 * @param builder the {@code PoolingHttpClientConnectionManagerBuilder} to customize
+		 */
+		void customize(PoolingHttpClientConnectionManagerBuilder builder);
+
+	}
+
 }

spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignHttpClient5ConfigurationTests.java

@@ -21,6 +21,7 @@
 import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
 import org.apache.hc.client5.http.impl.classic.HttpClientBuilder;
 import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
 import org.apache.hc.client5.http.io.HttpClientConnectionManager;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
@@ -29,6 +30,7 @@
 import org.springframework.boot.WebApplicationType;
 import org.springframework.boot.builder.SpringApplicationBuilder;
 import org.springframework.cloud.openfeign.clientconfig.HttpClient5FeignConfiguration.HttpClientBuilderCustomizer;
+import org.springframework.cloud.openfeign.clientconfig.HttpClient5FeignConfiguration.HttpClientConnectionManagerBuilderCustomizer;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
@@ -99,14 +101,35 @@ void shouldInstantiateHttpClient5ByUsingHttpClientBuilderCustomizer() {
 		}
 	}
 
+	@Test
+	void shouldInstantiateHttpClientConnectionManager5ByUsingHttpClientConnectionManagerBuilderCustomizer() {
+		ConfigurableApplicationContext context = new SpringApplicationBuilder().web(WebApplicationType.NONE)
+			.sources(FeignAutoConfiguration.class, Config.class)
+			.run();
+
+		HttpClientConnectionManager httpClientConnectionManager = context.getBean(HttpClientConnectionManager.class);
+		assertThat(httpClientConnectionManager).isNotNull();
+		HttpClientConnectionManagerBuilderCustomizer customizer = context.getBean(HttpClientConnectionManagerBuilderCustomizer.class);
+		verify(customizer).customize(any(PoolingHttpClientConnectionManagerBuilder.class));
+
+		if (context != null) {
+			context.close();
+		}
+	}
+
 	@Configuration
 	static class Config {
 
 		@Bean
-		HttpClientBuilderCustomizer customizer() {
+		HttpClientBuilderCustomizer httpClientCustomizer() {
 			return Mockito.mock(HttpClientBuilderCustomizer.class);
 		}
 
+		@Bean
+		HttpClientConnectionManagerBuilderCustomizer httpClientConnectionManagerCustomizer() {
+			return Mockito.mock(HttpClientConnectionManagerBuilderCustomizer.class);
+		}
+
 	}
 
 }