Merge branch 'timpeeters-2.1.x' into 2.1.x

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/filter/NettyRoutingFilter.java

@@ -119,6 +119,8 @@ public class NettyRoutingFilter implements GlobalFilter, Ordered {
 
 		Flux<HttpClientResponse> responseFlux = this.httpClient.headers(headers -> {
 			headers.add(httpHeaders);
+			// Will either be set below, or later by Netty
+			headers.remove(HttpHeaders.HOST);
 			if (preserveHost) {
 				String host = request.getHeaders().getFirst(HttpHeaders.HOST);
 				headers.add(HttpHeaders.HOST, host);

spring-cloud-gateway-core/src/test/java/org/springframework/cloud/gateway/filter/NettyRoutingFilterIntegrationTests.java

@@ -27,6 +27,7 @@ import org.springframework.context.annotation.Import;
 import org.springframework.http.HttpStatus;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.reactive.server.WebTestClient;
 
 import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
 
@@ -45,6 +46,18 @@ public class NettyRoutingFilterIntegrationTests extends BaseWebClientTests {
 				.isEqualTo("Response took longer than timeout: PT3S");
 	}
 
+	@Test
+	public void outboundHostHeaderNotOverwrittenByInbound() {
+		// different base url to have different host header in inbound / outbound requests
+		// Host: 127.0.0.1 -> request to Gateway, Host: localhost -> request from Gateway,
+		// resolved from lb://testservice
+		WebTestClient client = testClient.mutate().baseUrl("http://127.0.0.1:" + port)
+				.build();
+
+		client.get().uri("/headers").exchange().expectBody().jsonPath("$.headers.host")
+				.isEqualTo("localhost:" + port);
+	}
+
 	@EnableAutoConfiguration
 	@SpringBootConfiguration
 	@Import(DefaultTestConfig.class)