Adds ability to expand uri variables for other filters. (#711)

Currently only SetPath can use the uri variables from the path and host
predicates. Now, other filters can use them thru the
ServerWebExchangeUtils.expand() method.

fixes gh-704

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

@@ -341,6 +341,23 @@ spring:
 
 This will add `X-Request-Foo:Bar` header to the downstream request's headers for all matching requests.
 
+AddRequestHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: add_request_header_route
+        uri: https://example.org
+        predicates:
+        - Path=/foo/{segment}
+        filters:
+        - AddRequestHeader=X-Request-Foo, Bar-{segment}
+----
+
 === AddRequestParameter GatewayFilter Factory
 The AddRequestParameter GatewayFilter Factory takes a name and value parameter.
 
@@ -359,6 +376,23 @@ spring:
 
 This will add `foo=bar` to the downstream request's query string for all matching requests.
 
+AddRequestParameter is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: add_request_parameter_route
+        uri: https://example.org
+        predicates:
+        - Host: {segment}.myhost.org
+        filters:
+        - AddRequestParameter=foo, bar-{segment}
+----
+
 === AddResponseHeader GatewayFilter Factory
 The AddResponseHeader GatewayFilter Factory takes a name and value parameter.
 
@@ -377,6 +411,23 @@ spring:
 
 This will add `X-Response-Foo:Bar` header to the downstream response's headers for all matching requests.
 
+AddResponseHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: add_response_header_route
+        uri: https://example.org
+        predicates:
+        - Host: {segment}.myhost.org
+        filters:
+        - AddResponseHeader=foo, bar-{segment}
+----
+
 === DedupeResponseHeader GatewayFilter Factory
 The DedupeResponseHeader GatewayFilter Factory takes a `name` parameter and an optional `strategy` parameter. `name` can contain a list of header names, space separated.
 
@@ -839,6 +890,41 @@ spring:
 
 For a request path of `/foo/bar`, this will set the path to `/bar` before making the downstream request.
 
+=== SetRequestHeader GatewayFilter Factory
+The SetRequestHeader GatewayFilter Factory takes `name` and `value` parameters.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: setrequestheader_route
+        uri: https://example.org
+        filters:
+        - SetRequestHeader=X-Request-Foo, Bar
+----
+
+This GatewayFilter replaces all headers with the given name, rather than adding. So if the downstream server responded with a `X-Request-Foo:1234`, this would be replaced with `X-Request-Foo:Bar`, which is what the downstream service would receive.
+
+SetRequestHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: setrequestheader_route
+        uri: https://example.org
+        predicates:
+        - Host: {segment}.myhost.org
+        filters:
+        - SetRequestHeader=foo, bar-{segment}
+----
+
 === SetResponseHeader GatewayFilter Factory
 The SetResponseHeader GatewayFilter Factory takes `name` and `value` parameters.
 
@@ -857,6 +943,23 @@ spring:
 
 This GatewayFilter replaces all headers with the given name, rather than adding. So if the downstream server responded with a `X-Response-Foo:1234`, this would be replaced with `X-Response-Foo:Bar`, which is what the gateway client would receive.
 
+SetResponseHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime.
+
+.application.yml
+[source,yaml]
+----
+spring:
+  cloud:
+    gateway:
+      routes:
+      - id: setresponseheader_route
+        uri: https://example.org
+        predicates:
+        - Host: {segment}.myhost.org
+        filters:
+        - SetResponseHeader=foo, bar-{segment}
+----
+
 === SetStatus GatewayFilter Factory
 The SetStatus GatewayFilter Factory takes a single `status` parameter. It must be a valid Spring `HttpStatus`. It may be the integer value `404` or the string representation of the enumeration `NOT_FOUND`.
 

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

@@ -20,6 +20,7 @@ import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.web.server.ServerWebExchange;
 
@@ -37,8 +38,9 @@ public class AddRequestHeaderGatewayFilterFactory
 			@Override
 			public Mono<Void> filter(ServerWebExchange exchange,
 					GatewayFilterChain chain) {
+				String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
 				ServerHttpRequest request = exchange.getRequest().mutate()
-						.header(config.getName(), config.getValue()).build();
+						.header(config.getName(), value).build();
 
 				return chain.filter(exchange.mutate().request(request).build());
 			}

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

@@ -22,6 +22,7 @@ import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
@@ -52,10 +53,11 @@ public class AddRequestParameterGatewayFilterFactory
 					}
 				}
 
+				String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
 				// TODO urlencode?
 				query.append(config.getName());
 				query.append('=');
-				query.append(config.getValue());
+				query.append(value);
 
 				try {
 					URI newUri = UriComponentsBuilder.fromUri(uri)

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

@@ -20,6 +20,7 @@ import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.web.server.ServerWebExchange;
 
 import static org.springframework.cloud.gateway.support.GatewayToStringStyler.filterToStringCreator;
@@ -36,8 +37,8 @@ public class AddResponseHeaderGatewayFilterFactory
 			@Override
 			public Mono<Void> filter(ServerWebExchange exchange,
 					GatewayFilterChain chain) {
-				exchange.getResponse().getHeaders().add(config.getName(),
-						config.getValue());
+				String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
+				exchange.getResponse().getHeaders().add(config.getName(), value);
 
 				return chain.filter(exchange);
 			}

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

@@ -20,6 +20,7 @@ import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.web.server.ServerWebExchange;
 
@@ -37,9 +38,9 @@ public class SetRequestHeaderGatewayFilterFactory
 			@Override
 			public Mono<Void> filter(ServerWebExchange exchange,
 					GatewayFilterChain chain) {
+				String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
 				ServerHttpRequest request = exchange.getRequest().mutate()
-						.headers(
-								httpHeaders -> httpHeaders.set(config.name, config.value))
+						.headers(httpHeaders -> httpHeaders.set(config.name, value))
 						.build();
 
 				return chain.filter(exchange.mutate().request(request).build());

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

@@ -20,6 +20,7 @@ import reactor.core.publisher.Mono;
 
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.GatewayFilterChain;
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.web.server.ServerWebExchange;
 
 import static org.springframework.cloud.gateway.support.GatewayToStringStyler.filterToStringCreator;
@@ -36,8 +37,9 @@ public class SetResponseHeaderGatewayFilterFactory
 			@Override
 			public Mono<Void> filter(ServerWebExchange exchange,
 					GatewayFilterChain chain) {
+				String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
 				return chain.filter(exchange).then(Mono.fromRunnable(() -> exchange
-						.getResponse().getHeaders().set(config.name, config.value)));
+						.getResponse().getHeaders().set(config.name, value)));
 			}
 
 			@Override

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/support/ServerWebExchangeUtils.java

@@ -249,6 +249,19 @@ public final class ServerWebExchangeUtils {
 		return AsyncPredicate.from(predicate);
 	}
 
+	public static String expand(ServerWebExchange exchange, String template) {
+		Assert.notNull(exchange, "exchange may not be null");
+		Assert.notNull(template, "template may not be null");
+
+		if (template.indexOf('{') == -1) { // short circuit
+			return template;
+		}
+
+		Map<String, String> variables = getUriTemplateVariables(exchange);
+		return UriComponentsBuilder.fromPath(template).build().expand(variables)
+				.getPath();
+	}
+
 	@SuppressWarnings("unchecked")
 	public static void putUriTemplateVariables(ServerWebExchange exchange,
 			Map<String, String> uriVariables) {

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

@@ -66,7 +66,7 @@ public class AddRequestHeaderGatewayFilterFactoryTests extends BaseWebClientTest
 				.exchange().expectBody(Map.class).consumeWith(result -> {
 					Map<String, Object> headers = getMap(result.getResponseBody(),
 							"headers");
-					assertThat(headers).containsEntry("X-Request-Acme", "ValueB");
+					assertThat(headers).containsEntry("X-Request-Acme", "ValueB-www");
 				});
 	}
 
@@ -89,9 +89,9 @@ public class AddRequestHeaderGatewayFilterFactoryTests extends BaseWebClientTest
 		@Bean
 		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
 			return builder.routes().route("add_request_header_java_test",
-					r -> r.path("/headers").and().host("**.addrequestheaderjava.org")
+					r -> r.path("/headers").and().host("{sub}.addrequestheaderjava.org")
 							.filters(f -> f.prefixPath("/httpbin")
-									.addRequestHeader("X-Request-Acme", "ValueB"))
+									.addRequestHeader("X-Request-Acme", "ValueB-{sub}"))
 							.uri(uri))
 					.build();
 		}

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

@@ -68,7 +68,7 @@ public class AddRequestParameterGatewayFilterFactoryTests extends BaseWebClientT
 
 	@Test
 	public void addRequestParameterFilterWorksEncodedQueryJavaDsl() {
-		testRequestParameterFilter("www.addreqparamjava.org", "ValueB", "javaname",
+		testRequestParameterFilter("www.addreqparamjava.org", "ValueB-www", "javaname",
 				"%E6%89%8E%E6%A0%B9");
 	}
 
@@ -129,9 +129,9 @@ public class AddRequestParameterGatewayFilterFactoryTests extends BaseWebClientT
 		@Bean
 		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
 			return builder.routes().route("add_request_param_java_test",
-					r -> r.path("/get").and().host("**.addreqparamjava.org")
+					r -> r.path("/get").and().host("{sub}.addreqparamjava.org")
 							.filters(f -> f.prefixPath("/httpbin")
-									.addRequestParameter("example", "ValueB"))
+									.addRequestParameter("example", "ValueB-{sub}"))
 							.uri(uri))
 					.build();
 		}

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

@@ -59,7 +59,7 @@ public class AddResponseHeaderGatewayFilterFactoryTests extends BaseWebClientTes
 		URI uri = UriComponentsBuilder.fromUriString(this.baseUri + "/get").build(true)
 				.toUri();
 		String host = "www.addresponseheaderjava.org";
-		String expectedValue = "myresponsevalue";
+		String expectedValue = "myresponsevalue-www";
 		testClient.get().uri(uri).header("Host", host).exchange().expectHeader()
 				.valueEquals("example", expectedValue);
 	}
@@ -83,9 +83,9 @@ public class AddResponseHeaderGatewayFilterFactoryTests extends BaseWebClientTes
 		@Bean
 		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
 			return builder.routes().route("add_response_header_java_test",
-					r -> r.path("/get").and().host("**.addresponseheaderjava.org")
-							.filters(f -> f.prefixPath("/httpbin")
-									.addResponseHeader("example", "myresponsevalue"))
+					r -> r.path("/get").and().host("{sub}.addresponseheaderjava.org")
+							.filters(f -> f.prefixPath("/httpbin").addResponseHeader(
+									"example", "myresponsevalue-{sub}"))
 							.uri(uri))
 					.build();
 		}

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

@@ -55,7 +55,9 @@ public class SetRequestHeaderGatewayFilterFactoryTests extends BaseWebClientTest
 				.consumeWith(result -> {
 					Map<String, Object> headers = getMap(result.getResponseBody(),
 							"headers");
-					assertThat(headers).containsEntry("X-Req-Foo", "Second");
+					// add was called first, so sets will overwrite
+					assertThat(headers).doesNotContainEntry("X-Req-Foo", "First");
+					assertThat(headers).containsEntry("X-Req-Foo", "Second-www");
 				});
 	}
 
@@ -78,10 +80,10 @@ public class SetRequestHeaderGatewayFilterFactoryTests extends BaseWebClientTest
 		@Bean
 		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
 			return builder.routes().route("test_set_request_header",
-					r -> r.order(-1).host("**.setrequestheader.org")
+					r -> r.order(-1).host("{sub}.setrequestheader.org")
 							.filters(f -> f.prefixPath("/httpbin")
 									.addRequestHeader("X-Req-Foo", "First")
-									.setRequestHeader("X-Req-Foo", "Second"))
+									.setRequestHeader("X-Req-Foo", "Second-{sub}"))
 							.uri(uri))
 					.build();
 		}

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

@@ -19,12 +19,16 @@ package org.springframework.cloud.gateway.filter.factory;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.SpringBootConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.factory.AbstractNameValueGatewayFilterFactory.NameValueConfig;
+import org.springframework.cloud.gateway.route.RouteLocator;
+import org.springframework.cloud.gateway.route.builder.RouteLocatorBuilder;
 import org.springframework.cloud.gateway.test.BaseWebClientTests;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
@@ -41,7 +45,14 @@ public class SetResponseHeaderGatewayFilterFactoryTests extends BaseWebClientTes
 	public void setResponseHeaderFilterWorks() {
 		testClient.get().uri("/headers").header("Host", "www.setreresponseheader.org")
 				.exchange().expectStatus().isOk().expectHeader()
-				.valueEquals("X-Request-Foo", "Bar");
+				.valueEquals("X-Response-Foo", "Bar");
+	}
+
+	@Test
+	public void setResponseHeaderFilterWorksJavaDsl() {
+		testClient.get().uri("/headers").header("Host", "www.setresponseheaderdsl.org")
+				.exchange().expectStatus().isOk().expectHeader()
+				.valueEquals("X-Res-Foo", "Second-www");
 	}
 
 	@Test
@@ -57,6 +68,20 @@ public class SetResponseHeaderGatewayFilterFactoryTests extends BaseWebClientTes
 	@Import(DefaultTestConfig.class)
 	public static class TestConfig {
 
+		@Value("${test.uri}")
+		String uri;
+
+		@Bean
+		public RouteLocator testRouteLocator(RouteLocatorBuilder builder) {
+			return builder.routes().route("test_set_response_header_dsl",
+					r -> r.order(-1).host("{sub}.setresponseheaderdsl.org")
+							.filters(f -> f.prefixPath("/httpbin")
+									.addResponseHeader("X-Res-Foo", "First")
+									.setResponseHeader("X-Res-Foo", "Second-{sub}"))
+							.uri(uri))
+					.build();
+		}
+
 	}
 
 }

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

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2013-2019 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
+ *
+ *      https://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.support;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.web.server.MockServerWebExchange;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.expand;
+
+public class ServerWebExchangeUtilsTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Test
+	public void expandWorks() {
+		HashMap<String, String> vars = new HashMap<>();
+		vars.put("foo", "bar");
+		vars.put("baz", "bam");
+
+		MockServerWebExchange exchange = mockExchange(vars);
+
+		String expanded = expand(exchange, "my-{foo}-{baz}");
+		assertThat(expanded).isEqualTo("my-bar-bam");
+
+		expanded = expand(exchange, "my-noop");
+		assertThat(expanded).isEqualTo("my-noop");
+	}
+
+	@Test
+	public void missingVarThrowsException() {
+		MockServerWebExchange exchange = mockExchange(Collections.emptyMap());
+		thrown.expect(IllegalArgumentException.class);
+		expand(exchange, "my-{foo}-{baz}");
+	}
+
+	private MockServerWebExchange mockExchange(Map<String, String> vars) {
+		MockServerHttpRequest request = MockServerHttpRequest.get("/get").build();
+		MockServerWebExchange exchange = MockServerWebExchange.from(request);
+		ServerWebExchangeUtils.putUriTemplateVariables(exchange, vars);
+		return exchange;
+	}
+
+}

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

@@ -303,9 +303,9 @@ spring:
         - Host=**.setreresponseheader.org
         - Path=/headers
         filters:
-        - AddResponseHeader=X-Request-Foo, Bar1
-        - AddResponseHeader=X-Request-Foo, Bar2
-        - SetResponseHeader=X-Request-Foo, Bar
+        - AddResponseHeader=X-Response-Foo, Bar1
+        - AddResponseHeader=X-Response-Foo, Bar2
+        - SetResponseHeader=X-Response-Foo, Bar
 
       # =====================================
       - id: set_status_int_test