Rewrite response header filter factory.

docs/src/main/asciidoc/spring-cloud-gateway.adoc

@@ -620,6 +620,24 @@ spring:
 
 For a request path of `/foo/bar`, this will set the path to `/bar` before making the downstream request. Notice the `$\` which is replaced with `$` because of the YAML spec.
 
+=== RewriteResponseHeader GatewayFilter Factory
+The RewriteResponseHeader GatewayFilter Factory takes `name`, `regexp`, and `replacement` parameters. It uses Java regular expressions for a flexible way to rewrite the response header value.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: rewriteresponseheader_route
+        uri: http://example.org
+        filters:
+        - RewriteResponseHeader=X-Response-Foo, , password=[^&]+, password=***
+----
+
+For a header value of `/42?user=ford&password=omg!what&flag=true`, it will be set to `/42?user=ford&password=\***&flag=true` before making the downstream request. Please use `$\` to mean `$` because of the YAML spec.
+
 === SaveSession GatewayFilter Factory
 The SaveSession GatewayFilter Factory forces a `WebSession::save` operation _before_ forwarding the call downstream. This is of particular use when
 using something like http://projects.spring.io/spring-session/[Spring Session] with a lazy data store and need to ensure the session state has been saved before making the forwarded call.

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -24,6 +24,7 @@ import java.util.function.Consumer;
 import com.netflix.hystrix.HystrixObservableCommand;
 import io.netty.channel.ChannelOption;
 import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
+import org.springframework.cloud.gateway.filter.factory.*;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 import reactor.ipc.netty.http.client.HttpClient;
@@ -55,28 +56,6 @@ import org.springframework.cloud.gateway.filter.NettyWriteResponseFilter;
 import org.springframework.cloud.gateway.filter.RouteToRequestUrlFilter;
 import org.springframework.cloud.gateway.filter.WebsocketRoutingFilter;
 import org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter;
-import org.springframework.cloud.gateway.filter.factory.AddRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.AddRequestParameterGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.AddResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.GatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.HystrixGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.PrefixPathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.PreserveHostHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RedirectToGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RequestHeaderToRequestUriGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RequestRateLimiterGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RetryGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SaveSessionGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SecureHeadersGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties;
-import org.springframework.cloud.gateway.filter.factory.SetPathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetStatusGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.StripPrefixGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.rewrite.ModifyRequestBodyGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.rewrite.ModifyResponseBodyGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.headers.ForwardedHeadersFilter;
@@ -575,6 +554,11 @@ public class GatewayAutoConfiguration {
 		return new SetResponseHeaderGatewayFilterFactory();
 	}
 
+	@Bean
+	public RewriteResponseHeaderGatewayFilterFactory rewriteResponseHeaderGatewayFilterFactory() {
+		return new RewriteResponseHeaderGatewayFilterFactory();
+	}
+
 	@Bean
 	public SetStatusGatewayFilterFactory setStatusGatewayFilterFactory() {
 		return new SetStatusGatewayFilterFactory();

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

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2013-2018 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.cloud.gateway.filter.factory;
+
+import org.springframework.cloud.gateway.filter.GatewayFilter;
+import org.springframework.web.server.ServerWebExchange;
+import reactor.core.publisher.Mono;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * @author Vitaliy Pavlyuk
+ */
+public class RewriteResponseHeaderGatewayFilterFactory extends AbstractGatewayFilterFactory<RewriteResponseHeaderGatewayFilterFactory.Config> {
+
+	public static final String REGEXP_KEY = "regexp";
+	public static final String REPLACEMENT_KEY = "replacement";
+
+	public RewriteResponseHeaderGatewayFilterFactory() {
+		super(Config.class);
+	}
+
+	@Override
+	public List<String> shortcutFieldOrder() {
+		return Arrays.asList(NAME_KEY, REGEXP_KEY, REPLACEMENT_KEY);
+	}
+
+	@Override
+	public GatewayFilter apply(Config config) {
+		return (exchange, chain) -> chain.filter(exchange).then(Mono.fromRunnable(() -> {
+			rewriteHeader(exchange, config);
+		}));
+	}
+
+	protected void rewriteHeader(ServerWebExchange exchange, Config config) {
+		final String name = config.getName();
+		final String value = exchange.getResponse().getHeaders().getFirst(name);
+		if (value == null) {
+			return;
+		}
+		final String newValue = rewrite(value, config.getRegexp(), config.getReplacement());
+		exchange.getResponse().getHeaders().set(name, newValue);
+	}
+
+	String rewrite(String value, String regexp, String replacement) {
+		return value.replaceAll(regexp, replacement.replace("$\\", "$"));
+	}
+
+	public static class Config extends AbstractGatewayFilterFactory.NameConfig {
+		private String regexp;
+		private String replacement;
+
+		public String getRegexp() {
+			return regexp;
+		}
+
+		public Config setRegexp(String regexp) {
+			this.regexp = regexp;
+			return this;
+		}
+
+		public String getReplacement() {
+			return replacement;
+		}
+
+		public Config setReplacement(String replacement) {
+			this.replacement = replacement;
+			return this;
+		}
+	}
+}

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/route/builder/GatewayFilterSpec.java

@@ -29,33 +29,13 @@ import java.util.stream.Stream;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.cloud.gateway.filter.factory.*;
 import reactor.retry.Repeat;
 import reactor.retry.Retry;
 
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.OrderedGatewayFilter;
-import org.springframework.cloud.gateway.filter.factory.AbstractChangeRequestUriGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.AddRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.AddRequestParameterGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.AddResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.HystrixGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.PrefixPathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.PreserveHostHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RedirectToGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RequestHeaderToRequestUriGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RequestRateLimiterGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RetryGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SaveSessionGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SecureHeadersGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetPathGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetRequestHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetResponseHeaderGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.SetStatusGatewayFilterFactory;
-import org.springframework.cloud.gateway.filter.factory.StripPrefixGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.rewrite.ModifyRequestBodyGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.rewrite.ModifyResponseBodyGatewayFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.rewrite.RewriteFunction;
@@ -475,6 +455,18 @@ public class GatewayFilterSpec extends UriSpec {
 				.apply(c -> c.setName(headerName).setValue(headerValue)));
 	}
 
+	/**
+	 * A filter that rewrites a header value on the response before it is returned to the client by the Gateway.
+	 * @param headerName the header name
+	 * @param regex a Java regular expression to match the path against
+	 * @param replacement the replacement for the path
+	 * @return a {@link GatewayFilterSpec} that can be used to apply additional filters
+	 */
+	public GatewayFilterSpec rewriteResponseHeader(String headerName, String regex, String replacement) {
+		return filter(getBean(RewriteResponseHeaderGatewayFilterFactory.class)
+				.apply(c -> c.setReplacement(replacement).setRegexp(regex).setName(headerName)));
+	}
+
 	/**
 	 * A filter that sets the status on the response before it is returned to the client by the Gateway.
 	 * @param status the status to set on the response

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

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2013-2017 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.cloud.gateway.filter.factory;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.SpringBootConfiguration;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.cloud.gateway.test.BaseWebClientTests;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.springframework.boot.test.context.SpringBootTest.WebEnvironment.RANDOM_PORT;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(webEnvironment = RANDOM_PORT)
+@DirtiesContext
+public class RewriteResponseHeaderGatewayFilterFactoryTests extends BaseWebClientTests {
+
+	@Test
+	public void rewriteResponseHeaderFilterWorks() {
+		testClient.get()
+				.uri("/headers")
+				.header("Host", "www.rewriteresponseheader.org")
+				.exchange()
+				.expectStatus().isOk()
+				.expectHeader().valueEquals("X-Request-Foo", "/42?user=ford&password=***&flag=true");
+	}
+
+	@EnableAutoConfiguration
+	@SpringBootConfiguration
+	@Import(DefaultTestConfig.class)
+	public static class TestConfig { }
+
+}

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

@@ -25,21 +25,7 @@ import org.junit.runners.Suite;
 import org.junit.runners.Suite.SuiteClasses;
 import org.junit.runners.model.Statement;
 
-import org.springframework.cloud.gateway.filter.factory.AddRequestHeaderGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.AddRequestParameterGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.HystrixGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.PreserveHostHeaderGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.RedirectToGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.RequestRateLimiterGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactoryIntegrationTests;
-import org.springframework.cloud.gateway.filter.factory.RewritePathGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.SecureHeadersGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.SetPathGatewayFilterFactoryIntegrationTests;
-import org.springframework.cloud.gateway.filter.factory.SetPathGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.SetResponseHeaderGatewayFilterFactoryTests;
-import org.springframework.cloud.gateway.filter.factory.SetStatusGatewayFilterFactoryTests;
+import org.springframework.cloud.gateway.filter.factory.*;
 import org.springframework.cloud.gateway.filter.headers.ForwardedHeadersFilterTests;
 import org.springframework.cloud.gateway.filter.headers.RemoveHopByHopHeadersFilterTests;
 import org.springframework.cloud.gateway.filter.headers.XForwardedHeadersFilterTests;
@@ -89,6 +75,7 @@ import static org.junit.Assume.assumeThat;
 		SetPathGatewayFilterFactoryIntegrationTests.class,
 		AddRequestParameterGatewayFilterFactoryTests.class,
 		SetResponseHeaderGatewayFilterFactoryTests.class,
+		RewriteResponseHeaderGatewayFilterFactoryTests.class,
 		PrincipalNameKeyResolverIntegrationTests.class,
 		RedisRateLimiterTests.class,
 		RouteDefinitionRouteLocatorTests.class,

spring-cloud-gateway-core/src/test/resources/application.yml

@@ -65,6 +65,16 @@ spring:
         filters:
         - AddResponseHeader=X-Request-Foo, Bar
 
+      # =====================================
+      - id: rewrite_response_header_test
+        uri: ${test.uri}
+        predicates:
+        - Host=**.rewriteresponseheader.org
+        - Path=/headers
+        filters:
+        - AddResponseHeader=X-Request-Foo, /42?user=ford&password=omg!what&flag=true
+        - RewriteResponseHeader=X-Request-Foo, password=[^&]+, password=***
+
       # =====================================
       - id: forward_test
         uri: forward:/localcontroller