Extracts variables from Host Route Predicate.

fixes gh-706

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

@@ -146,11 +146,15 @@ spring:
       - id: host_route
         uri: http://example.org
         predicates:
-        - Host=**.somehost.org
+        - Host={sub}.somehost.org
 ----
 
+Ant patterns work as well, such as `**.somehost.org`.
+
 This route would match if the request has a `Host` header has the value `www.somehost.org` or `beta.somehost.org`.
 
+This predicate extracts the URI template variables (like `sub` defined in the example above) as a map of names and values and places it in the `ServerWebExchange.getAttributes()` with a key defined in `ServerWebExchangeUtils.URI_TEMPLATE_VARIABLES_ATTRIBUTE`. Those values are then available for use by <<gateway-route-filters,GatewayFilter Factories>>
+
 
 === Method Route Predicate Factory
 The Method Route Predicate Factory takes one parameter: the HTTP method to match.

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

@@ -28,7 +28,7 @@ import org.springframework.web.util.UriTemplate;
 
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.addOriginalRequestUrl;
-import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.getPathMatchVariables;
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.getUriTemplateVariables;
 
 /**
  * @author Spencer Gibb
@@ -54,7 +54,7 @@ public class SetPathGatewayFilterFactory extends AbstractGatewayFilterFactory<Se
 			ServerHttpRequest req = exchange.getRequest();
 			addOriginalRequestUrl(exchange, req.getURI());
 
-			Map<String, String> uriVariables = getPathMatchVariables(exchange);
+			Map<String, String> uriVariables = getUriTemplateVariables(exchange);
 
 			URI uri = uriTemplate.expand(uriVariables);
 			String newPath = uri.getRawPath();

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/HostRoutePredicateFactory.java

@@ -19,8 +19,10 @@ package org.springframework.cloud.gateway.handler.predicate;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.function.Predicate;
 
+import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
 import org.springframework.core.style.ToStringCreator;
 import org.springframework.util.AntPathMatcher;
 import org.springframework.util.PathMatcher;
@@ -51,7 +53,12 @@ public class HostRoutePredicateFactory extends AbstractRoutePredicateFactory<Hos
 	public Predicate<ServerWebExchange> apply(Config config) {
 		return exchange -> {
 			String host = exchange.getRequest().getHeaders().getFirst("Host");
-			return this.pathMatcher.match(config.getPattern(), host);
+			boolean match = this.pathMatcher.match(config.getPattern(), host);
+			if (match) {
+				Map<String, String> variables = this.pathMatcher.extractUriTemplateVariables(config.getPattern(), host);
+				ServerWebExchangeUtils.putUriTemplateVariables(exchange, variables);
+			}
+			return match;
 		};
 	}
 

spring-cloud-gateway-core/src/main/java/org/springframework/cloud/gateway/handler/predicate/PathRoutePredicateFactory.java

@@ -32,7 +32,7 @@ import org.springframework.web.util.pattern.PathPattern;
 import org.springframework.web.util.pattern.PathPattern.PathMatchInfo;
 import org.springframework.web.util.pattern.PathPatternParser;
 
-import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
+import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.putUriTemplateVariables;
 import static org.springframework.http.server.PathContainer.parsePath;
 
 /**
@@ -69,8 +69,8 @@ public class PathRoutePredicateFactory extends AbstractRoutePredicateFactory<Pat
 			boolean match = config.pathPattern.matches(path);
 			traceMatch("Pattern", config.pathPattern.getPatternString(), path, match);
 			if (match) {
-				PathMatchInfo uriTemplateVariables = config.pathPattern.matchAndExtract(path);
-				exchange.getAttributes().put(URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriTemplateVariables);
+				PathMatchInfo pathMatchInfo = config.pathPattern.matchAndExtract(path);
+				putUriTemplateVariables(exchange, pathMatchInfo.getUriVariables());
 			}
 			return match;
 		};

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

@@ -18,7 +18,7 @@
 package org.springframework.cloud.gateway.support;
 
 import java.net.URI;
-import java.util.Collections;
+import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Objects;
@@ -32,7 +32,6 @@ import org.springframework.cloud.gateway.handler.AsyncPredicate;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.server.reactive.AbstractServerHttpResponse;
 import org.springframework.web.server.ServerWebExchange;
-import org.springframework.web.util.pattern.PathPattern;
 
 /**
  * @author Spencer Gibb
@@ -127,12 +126,20 @@ public class ServerWebExchangeUtils {
 		return t -> Mono.just(predicate.test(t));
 	}
 
-	public static Map<String, String> getPathMatchVariables(ServerWebExchange exchange) {
-		PathPattern.PathMatchInfo variables = exchange.getAttribute(URI_TEMPLATE_VARIABLES_ATTRIBUTE);
-
-		if (variables != null) {
-			return variables.getUriVariables();
+	@SuppressWarnings("unchecked")
+	public static void putUriTemplateVariables(ServerWebExchange exchange, Map<String, String> uriVariables) {
+		if (exchange.getAttributes().containsKey(URI_TEMPLATE_VARIABLES_ATTRIBUTE)) {
+			Map<String, Object> existingVariables = (Map<String, Object>) exchange.getAttributes().get(URI_TEMPLATE_VARIABLES_ATTRIBUTE);
+			HashMap<String, Object> newVariables = new HashMap<>();
+			newVariables.putAll(existingVariables);
+			newVariables.putAll(uriVariables);
+			exchange.getAttributes().put(URI_TEMPLATE_VARIABLES_ATTRIBUTE, newVariables);
+		} else {
+			exchange.getAttributes().put(URI_TEMPLATE_VARIABLES_ATTRIBUTE, uriVariables);
 		}
-		return Collections.emptyMap();
+	}
+
+	public static Map<String, String> getUriTemplateVariables(ServerWebExchange exchange) {
+		return exchange.getAttributeOrDefault(URI_TEMPLATE_VARIABLES_ATTRIBUTE, new HashMap<>());
 	}
 }

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

@@ -40,7 +40,18 @@ public class SetPathGatewayFilterFactoryIntegrationTests extends BaseWebClientTe
 				.uri("/foo/get")
 				.header("Host", "www.setpath.org")
 				.exchange()
-				.expectStatus().isOk();
+				.expectStatus().isOk()
+				.expectHeader().valueEquals(ROUTE_ID_HEADER, "set_path_test");
+	}
+
+	@Test
+	public void setPathViaHostFilterWork() {
+		testClient.get()
+				.uri("/")
+				.header("Host", "get.setpathhost.org")
+				.exchange()
+				.expectStatus().isOk()
+				.expectHeader().valueEquals(ROUTE_ID_HEADER, "set_path_host_test");
 	}
 
 	@EnableAutoConfiguration

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

@@ -17,30 +17,25 @@
 
 package org.springframework.cloud.gateway.filter.factory;
 
-import java.lang.reflect.Constructor;
 import java.net.URI;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
-import java.util.Map;
 
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
+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.mock.http.server.reactive.MockServerHttpRequest;
 import org.springframework.mock.web.server.MockServerWebExchange;
-import org.springframework.util.ReflectionUtils;
 import org.springframework.web.server.ServerWebExchange;
-import org.springframework.cloud.gateway.filter.GatewayFilterChain;
-import org.springframework.web.util.pattern.PathPattern.PathMatchInfo;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.GATEWAY_ORIGINAL_REQUEST_URL_ATTR;
-import static org.springframework.cloud.gateway.support.ServerWebExchangeUtils.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
-
-import reactor.core.publisher.Mono;
 
 /**
  * @author Spencer Gibb
@@ -89,15 +84,7 @@ public class SetPathGatewayFilterFactoryTests {
 				.build();
 
 		ServerWebExchange exchange = MockServerWebExchange.from(request);
-
-		try {
-			Constructor<PathMatchInfo> constructor = ReflectionUtils.accessibleConstructor(PathMatchInfo.class, Map.class, Map.class);
-			constructor.setAccessible(true);
-			PathMatchInfo pathMatchInfo = constructor.newInstance(variables, Collections.emptyMap());
-			exchange.getAttributes().put(URI_TEMPLATE_VARIABLES_ATTRIBUTE, pathMatchInfo);
-		} catch (Exception e) {
-			ReflectionUtils.rethrowRuntimeException(e);
-		}
+		ServerWebExchangeUtils.putUriTemplateVariables(exchange, variables);
 
 		GatewayFilterChain filterChain = mock(GatewayFilterChain.class);
 

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

@@ -196,6 +196,14 @@ spring:
         filters:
         - SetPath=/{segment}
 
+        # =====================================
+      - id: set_path_host_test
+        uri: ${test.uri}
+        predicates:
+          - Host={subdomain}.setpathhost.org
+        filters:
+          - SetPath=/{subdomain}
+
       # =====================================
       - id: strip_prefix_test
         uri: ${test.uri}