Configure X-Forwarded-* support with Reactor Netty

This commit configures the new X-Forwarded-* / Forwarded HTTP headers
support with Reactor Netty in its 0.8.0 version.

Closes gh-10900

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/EmbeddedWebServerFactoryCustomizerAutoConfiguration.java

@@ -23,6 +23,7 @@ import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.util.Loader;
 import org.eclipse.jetty.webapp.WebAppContext;
 import org.xnio.SslClientAuthMode;
+import reactor.netty.http.server.HttpServer;
 
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -84,4 +85,19 @@ public class EmbeddedWebServerFactoryCustomizerAutoConfiguration {
 
 	}
 
+	/**
+	 * Nested configuration if Netty is being used.
+	 */
+	@Configuration
+	@ConditionalOnClass(HttpServer.class)
+	public static class NettyWebServerFactoryCustomizerConfiguration {
+
+		@Bean
+		public NettyWebServerFactoryCustomizer nettyWebServerFactoryCustomizer(
+				Environment environment, ServerProperties serverProperties) {
+			return new NettyWebServerFactoryCustomizer(environment, serverProperties);
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/NettyWebServerFactoryCustomizer.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2012-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.web.embedded;
+
+import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.cloud.CloudPlatform;
+import org.springframework.boot.web.embedded.netty.NettyReactiveWebServerFactory;
+import org.springframework.boot.web.server.WebServerFactoryCustomizer;
+import org.springframework.core.Ordered;
+import org.springframework.core.env.Environment;
+
+/**
+ * Customization for Netty-specific features.
+ *
+ * @author Brian Clozel
+ * @since 2.1.0
+ */
+public class NettyWebServerFactoryCustomizer
+		implements WebServerFactoryCustomizer<NettyReactiveWebServerFactory>, Ordered {
+
+	private final Environment environment;
+
+	private final ServerProperties serverProperties;
+
+	public NettyWebServerFactoryCustomizer(Environment environment,
+			ServerProperties serverProperties) {
+		this.environment = environment;
+		this.serverProperties = serverProperties;
+	}
+
+	@Override
+	public int getOrder() {
+		return 0;
+	}
+
+	@Override
+	public void customize(NettyReactiveWebServerFactory factory) {
+		factory.setUseForwardHeaders(
+				getOrDeduceUseForwardHeaders(this.serverProperties, this.environment));
+	}
+
+	private boolean getOrDeduceUseForwardHeaders(ServerProperties serverProperties,
+			Environment environment) {
+		if (serverProperties.isUseForwardHeaders() != null) {
+			return serverProperties.isUseForwardHeaders();
+		}
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		return platform != null && platform.isUsingForwardHeaders();
+	}
+
+}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/embedded/NettyWebServerFactoryCustomizerTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2012-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.web.embedded;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
+import org.springframework.boot.web.embedded.netty.NettyReactiveWebServerFactory;
+import org.springframework.mock.env.MockEnvironment;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Tests for {@link NettyWebServerFactoryCustomizer}.
+ *
+ * @author Brian Clozel
+ */
+public class NettyWebServerFactoryCustomizerTests {
+
+	private MockEnvironment environment;
+
+	private ServerProperties serverProperties;
+
+	private NettyWebServerFactoryCustomizer customizer;
+
+	@Before
+	public void setup() {
+		this.environment = new MockEnvironment();
+		this.serverProperties = new ServerProperties();
+		ConfigurationPropertySources.attach(this.environment);
+		this.customizer = new NettyWebServerFactoryCustomizer(this.environment,
+				this.serverProperties);
+	}
+
+	@Test
+	public void deduceUseForwardHeadersUndertow() {
+		this.environment.setProperty("DYNO", "-");
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(true);
+	}
+
+	@Test
+	public void defaultUseForwardHeadersUndertow() {
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(false);
+	}
+
+	@Test
+	public void setUseForwardHeadersUndertow() {
+		this.serverProperties.setUseForwardHeaders(true);
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(true);
+	}
+
+}