Add support for default filters.

fixes gh-23

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

@@ -84,9 +84,9 @@ public class GatewayAutoConfiguration {
 	}
 
 	@Bean
-	public FilteringWebHandler filteringWebHandler(List<GlobalFilter> globalFilters,
+	public FilteringWebHandler filteringWebHandler(GatewayProperties properties, List<GlobalFilter> globalFilters,
 												   Map<String, RouteFilter> routeFilters) {
-		return new FilteringWebHandler(globalFilters, routeFilters);
+		return new FilteringWebHandler(properties, globalFilters, routeFilters);
 	}
 
 	@Bean

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

@@ -4,6 +4,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.cloud.gateway.api.FilterDefinition;
 import org.springframework.cloud.gateway.api.Route;
 
 import javax.validation.Valid;
@@ -16,12 +17,17 @@ import javax.validation.constraints.NotNull;
 public class GatewayProperties {
 
 	/**
-	 * Map of route names to properties.
+	 * List of Routes
 	 */
 	@NotNull
 	@Valid
 	private List<Route> routes = new ArrayList<>();
 
+	/**
+	 * List of filter definitions that are applied to every route.
+	 */
+	private List<FilterDefinition> defaultFilters = new ArrayList<>();
+
 	public List<Route> getRoutes() {
 		return routes;
 	}
@@ -30,4 +36,11 @@ public class GatewayProperties {
 		this.routes = routes;
 	}
 
+	public List<FilterDefinition> getDefaultFilters() {
+		return defaultFilters;
+	}
+
+	public void setDefaultFilters(List<FilterDefinition> defaultFilters) {
+		this.defaultFilters = defaultFilters;
+	}
 }

src/main/java/org/springframework/cloud/gateway/handler/FilteringWebHandler.java

@@ -28,7 +28,9 @@ import java.util.stream.Collectors;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.cloud.gateway.api.FilterDefinition;
 import org.springframework.cloud.gateway.api.Route;
+import org.springframework.cloud.gateway.config.GatewayProperties;
 import org.springframework.cloud.gateway.filter.GlobalFilter;
 import org.springframework.cloud.gateway.filter.route.RouteFilter;
 import org.springframework.core.Ordered;
@@ -55,19 +57,21 @@ import reactor.core.publisher.Mono;
 public class FilteringWebHandler extends WebHandlerDecorator {
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	private final GatewayProperties gatewayProperties;
 	private final List<GlobalFilter> globalFilters;
 	private final Map<String, RouteFilter> routeFilters = new HashMap<>();
 
 	private final Map<String, List<WebFilter>> combinedFiltersForRoute = new HashMap<>();
 
-	public FilteringWebHandler(List<GlobalFilter> globalFilters,
+	public FilteringWebHandler(GatewayProperties gatewayProperties, List<GlobalFilter> globalFilters,
 							   Map<String, RouteFilter> routeFilters) {
-		this(new EmptyWebHandler(), globalFilters, routeFilters);
+		this(new EmptyWebHandler(), gatewayProperties, globalFilters, routeFilters);
 	}
 
-	public FilteringWebHandler(WebHandler targetHandler, List<GlobalFilter> globalFilters,
+	public FilteringWebHandler(WebHandler targetHandler, GatewayProperties gatewayProperties, List<GlobalFilter> globalFilters,
 							   Map<String, RouteFilter> routeFilters) {
 		super(targetHandler);
+		this.gatewayProperties = gatewayProperties;
 		this.globalFilters = initList(globalFilters);
 		routeFilters.forEach((name, def) -> this.routeFilters.put(normalizeName(name), def));
 	}
@@ -107,8 +111,14 @@ public class FilteringWebHandler extends WebHandlerDecorator {
 			//TODO: probably a java 8 stream way of doing this
 			combinedFilters = new ArrayList<>(loadFilters(this.globalFilters));
 
+			//TODO: support option to apply defaults after route specific filters?
+			if (!this.gatewayProperties.getDefaultFilters().isEmpty()) {
+				combinedFilters.addAll(loadWebFilters("defaultFilters",
+						this.gatewayProperties.getDefaultFilters()));
+			}
+
 			if (route.isPresent() && !route.get().getFilters().isEmpty()) {
-				combinedFilters.addAll(loadRouteFilters(route.get()));
+				combinedFilters.addAll(loadWebFilters(route.get().getId(), route.get().getFilters()));
 			}
 
 			AnnotationAwareOrderComparator.sort(combinedFilters);
@@ -129,8 +139,8 @@ public class FilteringWebHandler extends WebHandlerDecorator {
 				}).collect(Collectors.toList());
 	}
 
-	private List<WebFilter> loadRouteFilters(Route route) {
-		List<WebFilter> filters = route.getFilters().stream()
+	private List<WebFilter> loadWebFilters(String id, List<FilterDefinition> filterDefinitions) {
+		List<WebFilter> filters = filterDefinitions.stream()
 				.map(definition -> {
 					RouteFilter filter = this.routeFilters.get(definition.getName());
 					if (filter == null) {
@@ -143,7 +153,7 @@ public class FilteringWebHandler extends WebHandlerDecorator {
 						} else {
 							args = Collections.emptyList();
 						}
-						logger.debug("Route " + route.getId() + " applying filter " + args + " to " + definition.getName());
+						logger.debug("Route " + id + " applying filter " + args + " to " + definition.getName());
 					}
 					return filter.apply(definition.getArgs());
 				})

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

@@ -9,11 +9,13 @@ import org.apache.commons.logging.LogFactory;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.SpringBootConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.context.embedded.LocalServerPort;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.gateway.api.Route;
+import org.springframework.cloud.gateway.config.GatewayProperties;
 import org.springframework.cloud.gateway.filter.GlobalFilter;
 import org.springframework.cloud.gateway.filter.route.SecureHeadersProperties;
 import org.springframework.cloud.gateway.handler.RoutePredicateHandlerMapping;
@@ -73,6 +75,9 @@ public class GatewayIntegrationTests {
 	private WebClient webClient;
 	private String baseUri;
 
+	@Autowired
+	private GatewayProperties properties;
+
 	@Before
 	public void setup() {
 		//TODO: how to set new ReactorClientHttpConnector()
@@ -187,6 +192,27 @@ public class GatewayIntegrationTests {
 				.verify();
 	}
 
+	@Test
+	public void defaultFiltersWorks() {
+		assertThat(this.properties.getDefaultFilters()).isNotEmpty();
+
+		Mono<ClientResponse> result = webClient.get()
+				.uri("/headers")
+				.header("Host", "www.addresponseheader.org")
+				.exchange();
+
+		StepVerifier.create(result)
+				.consumeNextWith(
+						response -> {
+							HttpHeaders httpHeaders = response.headers().asHttpHeaders();
+							assertThat(httpHeaders.getFirst("X-Response-Default-Foo"))
+									.isEqualTo("Default-Bar");
+							assertThat(httpHeaders.get("X-Response-Default-Foo")).hasSize(1);
+						})
+				.expectComplete()
+				.verify(DURATION);
+	}
+
 	@Test
 	public void hostRouteWorks() {
 		Mono<ClientResponse> result = webClient.get()

src/test/resources/application.yml

@@ -2,6 +2,9 @@
 spring:
   cloud:
     gateway:
+      default-filters:
+      - AddResponseHeader=X-Response-Default-Foo, Default-Bar
+
       routes:
       # =====================================
       - host_example_to_httpbin=http://httpbin.org:80, Host=**.example.org