Allow customization of underlying ClientHttpRequestFactory components

Update `ClientHttpRequestFactoryBuilder` implementations for
`HttpComponents`, `Jdk`, `Jetty` and `Reactor` to allow customization
of the underlying components.

Closes gh-39035

Author: philwebb

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/AbstractClientHttpRequestFactoryBuilder.java

@@ -35,12 +35,20 @@
 abstract class AbstractClientHttpRequestFactoryBuilder<T extends ClientHttpRequestFactory>
 		implements ClientHttpRequestFactoryBuilder<T> {
 
+	private static final Consumer<?> EMPTY_CUSTOMIZER = (t) -> {
+	};
+
 	private final List<Consumer<T>> customizers;
 
 	protected AbstractClientHttpRequestFactoryBuilder(List<Consumer<T>> customizers) {
 		this.customizers = (customizers != null) ? customizers : Collections.emptyList();
 	}
 
+	@SuppressWarnings("unchecked")
+	protected static <T> Consumer<T> emptyCustomizer() {
+		return (Consumer<T>) EMPTY_CUSTOMIZER;
+	}
+
 	protected final List<Consumer<T>> getCustomizers() {
 		return this.customizers;
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/HttpComponentsClientHttpRequestFactoryBuilder.java

@@ -23,6 +23,7 @@
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 import org.apache.hc.client5.http.classic.HttpClient;
 import org.apache.hc.client5.http.impl.DefaultRedirectStrategy;
@@ -32,6 +33,7 @@
 import org.apache.hc.client5.http.protocol.RedirectStrategy;
 import org.apache.hc.client5.http.ssl.DefaultClientTlsStrategy;
 import org.apache.hc.client5.http.ssl.DefaultHostnameVerifier;
+import org.apache.hc.client5.http.ssl.TlsSocketStrategy;
 import org.apache.hc.core5.http.HttpRequest;
 import org.apache.hc.core5.http.HttpResponse;
 import org.apache.hc.core5.http.io.SocketConfig;
@@ -42,6 +44,7 @@
 import org.springframework.boot.ssl.SslBundle;
 import org.springframework.boot.ssl.SslOptions;
 import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -55,25 +58,104 @@
 public final class HttpComponentsClientHttpRequestFactoryBuilder
 		extends AbstractClientHttpRequestFactoryBuilder<HttpComponentsClientHttpRequestFactory> {
 
+	private final Consumer<HttpClientBuilder> httpClientCustomizer;
+
+	private final Consumer<PoolingHttpClientConnectionManagerBuilder> connectionManagerCustomizer;
+
+	private final Consumer<SocketConfig.Builder> socketConfigCustomizer;
+
+	private final Function<SslBundle, TlsSocketStrategy> tlsSocketStrategyFactory;
+
 	HttpComponentsClientHttpRequestFactoryBuilder() {
-		this(Collections.emptyList());
+		this(Collections.emptyList(), emptyCustomizer(), emptyCustomizer(), emptyCustomizer(),
+				HttpComponentsClientHttpRequestFactoryBuilder::createTlsSocketStrategy);
 	}
 
 	private HttpComponentsClientHttpRequestFactoryBuilder(
-			List<Consumer<HttpComponentsClientHttpRequestFactory>> customizers) {
+			List<Consumer<HttpComponentsClientHttpRequestFactory>> customizers,
+			Consumer<HttpClientBuilder> httpClientCustomizer,
+			Consumer<PoolingHttpClientConnectionManagerBuilder> connectionManagerCustomizer,
+			Consumer<SocketConfig.Builder> socketConfigCustomizer,
+			Function<SslBundle, TlsSocketStrategy> tlsSocketStrategyFactory) {
 		super(customizers);
+		this.httpClientCustomizer = httpClientCustomizer;
+		this.connectionManagerCustomizer = connectionManagerCustomizer;
+		this.socketConfigCustomizer = socketConfigCustomizer;
+		this.tlsSocketStrategyFactory = tlsSocketStrategyFactory;
 	}
 
 	@Override
 	public HttpComponentsClientHttpRequestFactoryBuilder withCustomizer(
 			Consumer<HttpComponentsClientHttpRequestFactory> customizer) {
-		return new HttpComponentsClientHttpRequestFactoryBuilder(mergedCustomizers(customizer));
+		return new HttpComponentsClientHttpRequestFactoryBuilder(mergedCustomizers(customizer),
+				this.httpClientCustomizer, this.connectionManagerCustomizer, this.socketConfigCustomizer,
+				this.tlsSocketStrategyFactory);
 	}
 
 	@Override
 	public HttpComponentsClientHttpRequestFactoryBuilder withCustomizers(
 			Collection<Consumer<HttpComponentsClientHttpRequestFactory>> customizers) {
-		return new HttpComponentsClientHttpRequestFactoryBuilder(mergedCustomizers(customizers));
+		return new HttpComponentsClientHttpRequestFactoryBuilder(mergedCustomizers(customizers),
+				this.httpClientCustomizer, this.connectionManagerCustomizer, this.socketConfigCustomizer,
+				this.tlsSocketStrategyFactory);
+	}
+
+	/**
+	 * Return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} that applies
+	 * additional customization to the underlying {@link HttpClientBuilder}.
+	 * @param httpClientCustomizer the customizer to apply
+	 * @return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} instance
+	 */
+	public HttpComponentsClientHttpRequestFactoryBuilder withHttpClientCustomizer(
+			Consumer<HttpClientBuilder> httpClientCustomizer) {
+		Assert.notNull(httpClientCustomizer, "'httpClientCustomizer' must not be null");
+		return new HttpComponentsClientHttpRequestFactoryBuilder(getCustomizers(),
+				this.httpClientCustomizer.andThen(httpClientCustomizer), this.connectionManagerCustomizer,
+				this.socketConfigCustomizer, this.tlsSocketStrategyFactory);
+	}
+
+	/**
+	 * Return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} that applies
+	 * additional customization to the underlying
+	 * {@link PoolingHttpClientConnectionManagerBuilder}.
+	 * @param connectionManagerCustomizer the customizer to apply
+	 * @return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} instance
+	 */
+	public HttpComponentsClientHttpRequestFactoryBuilder withConnectionManagerCustomizer(
+			Consumer<PoolingHttpClientConnectionManagerBuilder> connectionManagerCustomizer) {
+		Assert.notNull(connectionManagerCustomizer, "'connectionManagerCustomizer' must not be null");
+		return new HttpComponentsClientHttpRequestFactoryBuilder(getCustomizers(), this.httpClientCustomizer,
+				this.connectionManagerCustomizer.andThen(connectionManagerCustomizer), this.socketConfigCustomizer,
+				this.tlsSocketStrategyFactory);
+	}
+
+	/**
+	 * Return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} that applies
+	 * additional customization to the underlying
+	 * {@link org.apache.hc.core5.http.io.SocketConfig.Builder}.
+	 * @param socketConfigCustomizer the customizer to apply
+	 * @return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} instance
+	 */
+	public HttpComponentsClientHttpRequestFactoryBuilder withSocketConfigCustomizer(
+			Consumer<SocketConfig.Builder> socketConfigCustomizer) {
+		Assert.notNull(socketConfigCustomizer, "'socketConfigCustomizer' must not be null");
+		return new HttpComponentsClientHttpRequestFactoryBuilder(getCustomizers(), this.httpClientCustomizer,
+				this.connectionManagerCustomizer, this.socketConfigCustomizer.andThen(socketConfigCustomizer),
+				this.tlsSocketStrategyFactory);
+	}
+
+	/**
+	 * Return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} with a
+	 * replacement {@link TlsSocketStrategy} factory.
+	 * @param tlsSocketStrategyFactory the new factory used to create a
+	 * {@link TlsSocketStrategy} for a given {@link SslBundle}
+	 * @return a new {@link HttpComponentsClientHttpRequestFactoryBuilder} instance
+	 */
+	public HttpComponentsClientHttpRequestFactoryBuilder withTlsSocketStrategyFactory(
+			Function<SslBundle, TlsSocketStrategy> tlsSocketStrategyFactory) {
+		Assert.notNull(tlsSocketStrategyFactory, "'tlsSocketStrategyFactory' must not be null");
+		return new HttpComponentsClientHttpRequestFactoryBuilder(getCustomizers(), this.httpClientCustomizer,
+				this.connectionManagerCustomizer, this.socketConfigCustomizer, tlsSocketStrategyFactory);
 	}
 
 	@Override
@@ -87,11 +169,12 @@ protected HttpComponentsClientHttpRequestFactory createClientHttpRequestFactory(
 	}
 
 	private HttpClient createHttpClient(ClientHttpRequestFactorySettings settings) {
-		return HttpClientBuilder.create()
+		HttpClientBuilder builder = HttpClientBuilder.create()
 			.useSystemProperties()
 			.setRedirectStrategy(asRedirectStrategy(settings.redirects()))
-			.setConnectionManager(createConnectionManager(settings))
-			.build();
+			.setConnectionManager(createConnectionManager(settings));
+		this.httpClientCustomizer.accept(builder);
+		return builder.build();
 	}
 
 	private RedirectStrategy asRedirectStrategy(Redirects redirects) {
@@ -102,23 +185,31 @@ private RedirectStrategy asRedirectStrategy(Redirects redirects) {
 	}
 
 	private PoolingHttpClientConnectionManager createConnectionManager(ClientHttpRequestFactorySettings settings) {
-		PoolingHttpClientConnectionManagerBuilder builder = PoolingHttpClientConnectionManagerBuilder.create();
+		PoolingHttpClientConnectionManagerBuilder builder = PoolingHttpClientConnectionManagerBuilder.create()
+			.useSystemProperties();
+		PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
+		builder.setDefaultSocketConfig(createSocketConfig(settings));
+		map.from(settings::sslBundle).as(this.tlsSocketStrategyFactory).to(builder::setTlsSocketStrategy);
+		this.connectionManagerCustomizer.accept(builder);
+		return builder.build();
+	}
+
+	private SocketConfig createSocketConfig(ClientHttpRequestFactorySettings settings) {
+		SocketConfig.Builder builder = SocketConfig.custom();
 		PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
-		map.from(settings::readTimeout).as(this::createSocketConfig).to(builder::setDefaultSocketConfig);
-		map.from(settings::sslBundle).as(this::createTlsSocketStrategy).to(builder::setTlsSocketStrategy);
-		return builder.useSystemProperties().build();
+		map.from(settings::readTimeout)
+			.asInt(Duration::toMillis)
+			.to((timeout) -> builder.setSoTimeout(timeout, TimeUnit.MILLISECONDS));
+		this.socketConfigCustomizer.accept(builder);
+		return builder.build();
 	}
 
-	private DefaultClientTlsStrategy createTlsSocketStrategy(SslBundle sslBundle) {
+	private static TlsSocketStrategy createTlsSocketStrategy(SslBundle sslBundle) {
 		SslOptions options = sslBundle.getOptions();
 		return new DefaultClientTlsStrategy(sslBundle.createSslContext(), options.getEnabledProtocols(),
 				options.getCiphers(), null, new DefaultHostnameVerifier());
 	}
 
-	private SocketConfig createSocketConfig(Duration readTimeout) {
-		return SocketConfig.custom().setSoTimeout((int) readTimeout.toMillis(), TimeUnit.MILLISECONDS).build();
-	}
-
 	/**
 	 * {@link RedirectStrategy} that never follows redirects.
 	 */

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/JdkClientHttpRequestFactoryBuilder.java

@@ -26,6 +26,7 @@
 import org.springframework.boot.http.client.ClientHttpRequestFactorySettings.Redirects;
 import org.springframework.boot.ssl.SslBundle;
 import org.springframework.http.client.JdkClientHttpRequestFactory;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -39,23 +40,40 @@
 public class JdkClientHttpRequestFactoryBuilder
 		extends AbstractClientHttpRequestFactoryBuilder<JdkClientHttpRequestFactory> {
 
+	private final Consumer<HttpClient.Builder> httpClientCustomizer;
+
 	JdkClientHttpRequestFactoryBuilder() {
-		this(null);
+		this(null, emptyCustomizer());
 	}
 
-	private JdkClientHttpRequestFactoryBuilder(List<Consumer<JdkClientHttpRequestFactory>> customizers) {
+	private JdkClientHttpRequestFactoryBuilder(List<Consumer<JdkClientHttpRequestFactory>> customizers,
+			Consumer<HttpClient.Builder> httpClientCustomizer) {
 		super(customizers);
+		this.httpClientCustomizer = httpClientCustomizer;
 	}
 
 	@Override
 	public JdkClientHttpRequestFactoryBuilder withCustomizer(Consumer<JdkClientHttpRequestFactory> customizer) {
-		return new JdkClientHttpRequestFactoryBuilder(mergedCustomizers(customizer));
+		return new JdkClientHttpRequestFactoryBuilder(mergedCustomizers(customizer), this.httpClientCustomizer);
 	}
 
 	@Override
 	public JdkClientHttpRequestFactoryBuilder withCustomizers(
 			Collection<Consumer<JdkClientHttpRequestFactory>> customizers) {
-		return new JdkClientHttpRequestFactoryBuilder(mergedCustomizers(customizers));
+		return new JdkClientHttpRequestFactoryBuilder(mergedCustomizers(customizers), this.httpClientCustomizer);
+	}
+
+	/**
+	 * Return a new {@link JdkClientHttpRequestFactoryBuilder} that applies additional
+	 * customization to the underlying {@link java.net.http.HttpClient.Builder}.
+	 * @param httpClientCustomizer the customizer to apply
+	 * @return a new {@link JdkClientHttpRequestFactoryBuilder} instance
+	 */
+	public JdkClientHttpRequestFactoryBuilder withHttpClientCustomizer(
+			Consumer<HttpClient.Builder> httpClientCustomizer) {
+		Assert.notNull(httpClientCustomizer, "'httpClientCustomizer' must not be null");
+		return new JdkClientHttpRequestFactoryBuilder(getCustomizers(),
+				this.httpClientCustomizer.andThen(httpClientCustomizer));
 	}
 
 	@Override
@@ -68,12 +86,13 @@ protected JdkClientHttpRequestFactory createClientHttpRequestFactory(ClientHttpR
 	}
 
 	private HttpClient createHttpClient(ClientHttpRequestFactorySettings settings) {
-		HttpClient.Builder httpClientBuilder = HttpClient.newBuilder();
+		HttpClient.Builder builder = HttpClient.newBuilder();
 		PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
-		map.from(settings::connectTimeout).to(httpClientBuilder::connectTimeout);
-		map.from(settings::sslBundle).as(SslBundle::createSslContext).to(httpClientBuilder::sslContext);
-		map.from(settings::redirects).as(this::asHttpClientRedirect).to(httpClientBuilder::followRedirects);
-		return httpClientBuilder.build();
+		map.from(settings::connectTimeout).to(builder::connectTimeout);
+		map.from(settings::sslBundle).as(SslBundle::createSslContext).to(builder::sslContext);
+		map.from(settings::redirects).as(this::asHttpClientRedirect).to(builder::followRedirects);
+		this.httpClientCustomizer.accept(builder);
+		return builder.build();
 	}
 
 	private Redirect asHttpClientRedirect(Redirects redirects) {