Add SetPath filter

src/main/java/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java

@@ -16,6 +16,7 @@ import org.springframework.cloud.gateway.filter.RouteToRequestUrlFilter;
 import org.springframework.cloud.gateway.filter.factory.RemoveRequestHeaderFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RemoveResponseHeaderFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.RewritePathFilterFactory;
+import org.springframework.cloud.gateway.filter.factory.SetPathFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.SetResponseHeaderFilterFactory;
 import org.springframework.cloud.gateway.filter.factory.SetStatusFilterFactory;
 import org.springframework.cloud.gateway.handler.GatewayFilteringWebHandler;
@@ -140,6 +141,11 @@ public class GatewayAutoConfiguration {
 		return new RewritePathFilterFactory();
 	}
 
+	@Bean
+	public SetPathFilterFactory setPathFilterFactory() {
+		return new SetPathFilterFactory();
+	}
+
 	@Bean
 	public SetResponseHeaderFilterFactory setResponseHeaderFilterFactory() {
 		return new SetResponseHeaderFilterFactory();

src/main/java/org/springframework/cloud/gateway/filter/GatewayFilter.java

@@ -44,7 +44,7 @@ public interface GatewayFilter {
 	 */
 	Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain);
 
-	default <T> T getAttribute(ServerWebExchange exchange, String attributeName, Class<T> type) {
+	static <T> T getAttribute(ServerWebExchange exchange, String attributeName, Class<T> type) {
 		if (exchange.getAttributes().containsKey(attributeName)) {
 			Object attr = exchange.getAttributes().get(attributeName);
 			if (type.isAssignableFrom(attr.getClass())) {

src/main/java/org/springframework/cloud/gateway/filter/RouteToRequestUrlFilter.java

@@ -10,6 +10,8 @@ import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebFilterChain;
 import org.springframework.web.util.UriComponentsBuilder;
 
+import static org.springframework.cloud.gateway.filter.GatewayFilter.getAttribute;
+
 import reactor.core.publisher.Mono;
 
 /**

src/main/java/org/springframework/cloud/gateway/filter/factory/SetPathFilterFactory.java

@@ -0,0 +1,37 @@
+package org.springframework.cloud.gateway.filter.factory;
+
+import java.net.URI;
+import java.util.Map;
+
+import org.springframework.cloud.gateway.filter.GatewayFilter;
+import org.springframework.http.server.reactive.ServerHttpRequest;
+import org.springframework.web.util.UriTemplate;
+
+import static org.springframework.cloud.gateway.filter.GatewayFilter.getAttribute;
+import static org.springframework.cloud.gateway.handler.predicate.UrlPredicateFactory.URL_PREDICATE_VARS_ATTR;
+
+/**
+ * @author Spencer Gibb
+ */
+public class SetPathFilterFactory implements FilterFactory {
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public GatewayFilter apply(String template, String[] args) {
+		UriTemplate uriTemplate = new UriTemplate(template);
+
+		//TODO: caching can happen here
+		return (exchange, chain) -> {
+			Map<String, String> variables = getAttribute(exchange, URL_PREDICATE_VARS_ATTR, Map.class);
+			ServerHttpRequest req = exchange.getRequest();
+			URI uri = uriTemplate.expand(variables);
+			String newPath = uri.getPath();
+
+			ServerHttpRequest request = req.mutate()
+					.path(newPath)
+					.build();
+
+			return chain.filter(exchange.mutate().request(request).build());
+		};
+	}
+}

src/main/java/org/springframework/cloud/gateway/handler/predicate/UrlPredicateFactory.java

@@ -1,5 +1,6 @@
 package org.springframework.cloud.gateway.handler.predicate;
 
+import java.util.Map;
 import java.util.function.Predicate;
 
 import org.springframework.util.AntPathMatcher;
@@ -12,6 +13,8 @@ import org.springframework.web.server.support.HttpRequestPathHelper;
  */
 public class UrlPredicateFactory implements PredicateFactory {
 
+	public static final String URL_PREDICATE_VARS_ATTR = "urlPredicateVars";
+
 	private PathMatcher pathMatcher = new AntPathMatcher();
 	private HttpRequestPathHelper pathHelper = new HttpRequestPathHelper();
 
@@ -40,7 +43,12 @@ public class UrlPredicateFactory implements PredicateFactory {
 	public Predicate<ServerWebExchange> apply(String pattern, String[] args) {
 		return exchange -> {
 			String lookupPath = getPathHelper().getLookupPathForRequest(exchange);
-			return getPathMatcher().match(pattern, lookupPath);
+			boolean match = getPathMatcher().match(pattern, lookupPath);
+			if (match) {
+				Map<String, String> variables = getPathMatcher().extractUriTemplateVariables(pattern, lookupPath);
+				exchange.getAttributes().put(URL_PREDICATE_VARS_ATTR, variables);
+			}
+			return match;
 			//TODO: support trailingSlashMatch
 		};
 	}

src/test/java/org/springframework/cloud/gateway/filter/factory/SetPathFilterFactoryTests.java

@@ -0,0 +1,60 @@
+package org.springframework.cloud.gateway.filter.factory;
+
+import org.assertj.core.api.Assertions;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.springframework.cloud.gateway.filter.GatewayFilter;
+import org.springframework.cloud.gateway.handler.predicate.UrlPredicateFactory;
+import org.springframework.mock.http.server.reactive.MockServerHttpRequest;
+import org.springframework.mock.http.server.reactive.MockServerHttpResponse;
+import org.springframework.web.server.ServerWebExchange;
+import org.springframework.web.server.WebFilterChain;
+import org.springframework.web.server.adapter.DefaultServerWebExchange;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import reactor.core.publisher.Mono;
+
+import java.util.HashMap;
+
+/**
+ * @author Spencer Gibb
+ */
+public class SetPathFilterFactoryTests {
+
+	@Test
+	public void rewritePathFilterWorks() {
+		HashMap<String, String> variables = new HashMap<>();
+		testRewriteFilter("/baz/bar", "/foo/bar", "/baz/bar", variables);
+	}
+
+	@Test
+	public void setPathFilterWithTemplateVarsWorks() {
+		HashMap<String, String> variables = new HashMap<>();
+		variables.put("id", "123");
+		testRewriteFilter("/bar/baz/{id}", "/foo/123", "/bar/baz/123", variables);
+	}
+
+	private void testRewriteFilter(String template, String actualPath, String expectedPath, HashMap<String, String> variables) {
+		GatewayFilter filter = new SetPathFilterFactory().apply(template, new String[]{});
+
+		MockServerHttpRequest request = MockServerHttpRequest
+				.get("http://localhost"+ actualPath)
+				.build();
+
+		DefaultServerWebExchange exchange = new DefaultServerWebExchange(request, new MockServerHttpResponse());
+		exchange.getAttributes().put(UrlPredicateFactory.URL_PREDICATE_VARS_ATTR, variables);
+
+		WebFilterChain filterChain = mock(WebFilterChain.class);
+
+		ArgumentCaptor<ServerWebExchange> captor = ArgumentCaptor.forClass(ServerWebExchange.class);
+		when(filterChain.filter(captor.capture())).thenReturn(Mono.empty());
+
+		filter.filter(exchange, filterChain);
+
+		ServerWebExchange webExchange = captor.getValue();
+
+		Assertions.assertThat(webExchange.getRequest().getURI().getPath()).isEqualTo(expectedPath);
+	}
+}

src/test/java/org/springframework/cloud/gateway/test/GatewayIntegrationTests.java

@@ -258,6 +258,26 @@ public class GatewayIntegrationTests {
 		);
 	}
 
+	@Test
+	public void setPathFilterWorks() {
+		Mono<ClientResponse> result = webClient.exchange(
+				GET("http://localhost:" + port + "/foo/get")
+						.header("Host", "www.setpath.org")
+						.build()
+		);
+
+		verify( () ->
+				StepVerifier.create(result)
+						.consumeNextWith(
+								response -> {
+									HttpStatus statusCode = response.statusCode();
+									assertThat(statusCode).isEqualTo(HttpStatus.OK);
+								})
+						.expectComplete()
+						.verify(Duration.ofSeconds(3))
+		);
+	}
+
 	@Test
 	public void setResponseHeaderFilterWorks() {
 		Mono<ClientResponse> result = webClient.exchange(
@@ -281,14 +301,14 @@ public class GatewayIntegrationTests {
 
 	@Test
 	@Ignore("TODO: figure out how to set the status before response committed")
-	public void setStatusStringWorks() {
-		setStatusStringTest("www.setstatusstring.org", HttpStatus.BAD_REQUEST);
+	public void setStatusIntWorks() {
+		setStatusStringTest("www.setstatusint.org", HttpStatus.UNAUTHORIZED);
 	}
 
 	@Test
 	@Ignore("TODO: figure out how to set the status before response committed")
-	public void setStatusIntWorks() {
-		setStatusStringTest("www.setstatusint.org", HttpStatus.UNAUTHORIZED);
+	public void setStatusStringWorks() {
+		setStatusStringTest("www.setstatusstring.org", HttpStatus.BAD_REQUEST);
 	}
 
 	private void setStatusStringTest(String host, HttpStatus status) {

src/test/resources/application.yml

@@ -57,6 +57,15 @@ spring:
         - AddResponseHeader=X-Request-Foo, Bar
         - RemoveResponseHeader=X-Request-Foo
 
+      # =====================================
+      - id: set_path_test
+        uri: http://httpbin.org:80
+        predicates:
+        - Host=**.setpath.org
+        - Url=/foo/{segment}
+        filters:
+        - SetPath=/{segment}
+
       # =====================================
       - id: set_response_header_test
         uri: http://httpbin.org:80
@@ -69,22 +78,22 @@ spring:
         - SetResponseHeader=X-Request-Foo, Bar
 
       # =====================================
-      - id: set_status_string_test
+      - id: set_status_int_test
         uri: http://httpbin.org:80
         predicates:
-        - Host=**.setstatusstring.org
+        - Host=**.setstatusint.org
         - Url=/headers
         filters:
-        - SetStatus=BAD_REQUEST
+        - SetStatus=401
 
       # =====================================
-      - id: set_status_int_test
+      - id: set_status_string_test
         uri: http://httpbin.org:80
         predicates:
-        - Host=**.setstatusint.org
+        - Host=**.setstatusstring.org
         - Url=/headers
         filters:
-        - SetStatus=401
+        - SetStatus=BAD_REQUEST
 
       # =====================================
       - id: rewrite_path_test