Make /error path a special case in ZuulHandlerMapping

If there is a default route (/**) then the ZuulHandlerMapping will
mask the /error path in a normal Spring Boot application. This change
makes it a special case so that ZuulHandlerMapping will never map
the /error route (the one specified by the ErrorController).

Fixes gh-284

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/ZuulConfiguration.java

@@ -20,6 +20,7 @@ import java.util.Map;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.web.ErrorController;
 import org.springframework.boot.context.embedded.ServletRegistrationBean;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.context.scope.refresh.RefreshScopeRefreshedEvent;
@@ -54,6 +55,9 @@ public class ZuulConfiguration {
 	@Autowired
 	private ZuulProperties zuulProperties;
 
+	@Autowired(required = false)
+	private ErrorController errorController;
+
 	@Bean
 	public RouteLocator routeLocator() {
 		return new SimpleRouteLocator(this.zuulProperties);
@@ -66,7 +70,9 @@ public class ZuulConfiguration {
 
 	@Bean
 	public ZuulHandlerMapping zuulHandlerMapping(RouteLocator routes) {
-		return new ZuulHandlerMapping(routes, zuulController());
+		ZuulHandlerMapping mapping = new ZuulHandlerMapping(routes, zuulController());
+		mapping.setErrorController(this.errorController);
+		return mapping;
 	}
 
 	@Bean

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/web/ZuulHandlerMapping.java

@@ -18,7 +18,9 @@ package org.springframework.cloud.netflix.zuul.web;
 
 import java.util.Collection;
 
-import org.springframework.beans.factory.annotation.Autowired;
+import javax.servlet.http.HttpServletRequest;
+
+import org.springframework.boot.autoconfigure.web.ErrorController;
 import org.springframework.cloud.netflix.zuul.filters.RouteLocator;
 import org.springframework.web.servlet.handler.AbstractUrlHandlerMapping;
 
@@ -34,13 +36,28 @@ public class ZuulHandlerMapping extends AbstractUrlHandlerMapping {
 
 	private final ZuulController zuul;
 
-	@Autowired
+	private ErrorController errorController;
+
 	public ZuulHandlerMapping(RouteLocator routeLocator, ZuulController zuul) {
 		this.routeLocator = routeLocator;
 		this.zuul = zuul;
 		setOrder(-200);
 	}
 
+	public void setErrorController(ErrorController errorController) {
+		this.errorController = errorController;
+	}
+
+	@Override
+	protected Object lookupHandler(String urlPath, HttpServletRequest request)
+			throws Exception {
+		if (this.errorController != null
+				&& urlPath.equals(this.errorController.getErrorPath())) {
+			return null;
+		}
+		return super.lookupHandler(urlPath, request);
+	}
+
 	public void registerHandlers() {
 		Collection<String> routes = this.routeLocator.getRoutePaths();
 		if (routes.isEmpty()) {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/web/ZuulHandlerMappingTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2013-2015 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.netflix.zuul.web;
+
+import java.util.Arrays;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+import org.springframework.boot.autoconfigure.web.ErrorController;
+import org.springframework.cloud.netflix.zuul.filters.RouteLocator;
+import org.springframework.mock.web.MockHttpServletRequest;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+/**
+ * @author Dave Syer
+ */
+public class ZuulHandlerMappingTests {
+
+	private ZuulHandlerMapping mapping;
+
+	private RouteLocator locator = Mockito.mock(RouteLocator.class);
+
+	private ErrorController errors = Mockito.mock(ErrorController.class);
+
+	private MockHttpServletRequest request = new MockHttpServletRequest();
+
+	@Before
+	public void init() {
+		this.mapping = new ZuulHandlerMapping(this.locator, new ZuulController());
+		this.mapping.setErrorController(this.errors);
+		Mockito.when(this.errors.getErrorPath()).thenReturn("/error");
+	}
+
+	@Test
+	public void mappedPath() throws Exception {
+		Mockito.when(this.locator.getRoutePaths()).thenReturn(Arrays.asList("/foo/**"));
+		this.request.setServletPath("/foo/");
+		this.mapping.registerHandlers();
+		assertNotNull(this.mapping.getHandler(this.request));
+	}
+
+	@Test
+	public void defaultPath() throws Exception {
+		Mockito.when(this.locator.getRoutePaths()).thenReturn(Arrays.asList("/**"));
+		this.request.setServletPath("/");
+		this.mapping.registerHandlers();
+		assertNotNull(this.mapping.getHandler(this.request));
+	}
+
+	@Test
+	public void errorPath() throws Exception {
+		Mockito.when(this.locator.getRoutePaths()).thenReturn(Arrays.asList("/**"));
+		this.request.setServletPath("/error");
+		this.mapping.registerHandlers();
+		assertNull(this.mapping.getHandler(this.request));
+	}
+
+}