Merge pull request #2255 from DominikMostek/fallback_cause

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

@@ -1978,6 +1978,68 @@ class MyFallbackProvider implements ZuulFallbackProvider {
 }
 ----
 
+If you would like to choose the response based on the cause of the failure use `FallbackProvider` which will replace `ZuulFallbackProvder` in future versions.
+
+[source,java]
+----
+class MyFallbackProvider implements FallbackProvider {
+
+    @Override
+    public String getRoute() {
+        return "*";
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse(final Throwable cause) {
+        if (cause instanceof HystrixTimeoutException) {
+            return response(HttpStatus.GATEWAY_TIMEOUT);
+        } else {
+            return fallbackResponse();
+        }
+    }
+
+    @Override
+    public ClientHttpResponse fallbackResponse() {
+        return response(HttpStatus.INTERNAL_SERVER_ERROR);
+    }
+
+    private ClientHttpResponse response(final HttpStatus status) {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return status;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return status.value();
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return status.getReasonPhrase();
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("fallback".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                HttpHeaders headers = new HttpHeaders();
+                headers.setContentType(MediaType.APPLICATION_JSON);
+                return headers;
+            }
+        };
+    }
+}
+----
+
 [[zuul-redirect-location-rewrite]]
 === Rewriting `Location` header
 

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/FallbackProvider.java

+/*
+ * Copyright 2017 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.filters.route;
+
+import org.springframework.http.client.ClientHttpResponse;
+
+/**
+ * Extension of {@link ZuulFallbackProvider} which adds possibility to choose proper response
+ * based on the exception which caused the main method to fail.
+ *
+ * @author Dominik Mostek
+ */
+public interface FallbackProvider extends ZuulFallbackProvider {
+
+    /**
+     * Provides a fallback response based on the cause of the failed execution.
+     *
+     * @param cause cause of the main method failure
+     * @return the fallback response
+     */
+    ClientHttpResponse fallbackResponse(Throwable cause);
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/ZuulFallbackProvider.java

@@ -23,7 +23,9 @@ import org.springframework.http.client.ClientHttpResponse;
 /**
  * Provides fallback when a failure occurs on a route.
  * @author Ryan Baxter
+ * @deprecated Use {@link FallbackProvider}
  */
+@Deprecated
 public interface ZuulFallbackProvider {
 
 	/**

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/support/AbstractRibbonCommand.java

@@ -23,6 +23,7 @@ import org.springframework.cloud.netflix.zuul.filters.ZuulProperties;
 import org.springframework.cloud.netflix.zuul.filters.route.RibbonCommand;
 import org.springframework.cloud.netflix.zuul.filters.route.RibbonCommandContext;
 import org.springframework.cloud.netflix.zuul.filters.route.ZuulFallbackProvider;
+import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
 import org.springframework.http.client.ClientHttpResponse;
 import com.netflix.client.AbstractLoadBalancerAwareClient;
 import com.netflix.client.ClientRequest;
@@ -69,7 +70,13 @@ public abstract class AbstractRibbonCommand<LBC extends AbstractLoadBalancerAwar
 	public AbstractRibbonCommand(String commandKey, LBC client,
 								 RibbonCommandContext context, ZuulProperties zuulProperties,
 								 ZuulFallbackProvider fallbackProvider, IClientConfig config) {
-		super(getSetter(commandKey, zuulProperties));
+		this(getSetter(commandKey, zuulProperties), client, context, fallbackProvider, config);
+	}
+
+	protected AbstractRibbonCommand(Setter setter, LBC client,
+								 RibbonCommandContext context,
+								 ZuulFallbackProvider fallbackProvider, IClientConfig config) {
+		super(setter);
 		this.client = client;
 		this.context = context;
 		this.zuulFallbackProvider = fallbackProvider;
@@ -126,11 +133,24 @@ public abstract class AbstractRibbonCommand<LBC extends AbstractLoadBalancerAwar
 	@Override
 	protected ClientHttpResponse getFallback() {
 		if(zuulFallbackProvider != null) {
-			return zuulFallbackProvider.fallbackResponse();
+			return getFallbackResponse();
 		}
 		return super.getFallback();
 	}
 
+	protected ClientHttpResponse getFallbackResponse() {
+		if (zuulFallbackProvider instanceof FallbackProvider) {
+			Throwable cause = getFailedExecutionException();
+			cause = cause == null ? getExecutionException() : cause;
+			if (cause == null) {
+				zuulFallbackProvider.fallbackResponse();
+			} else {
+				return ((FallbackProvider) zuulFallbackProvider).fallbackResponse(cause);
+			}
+		}
+		return zuulFallbackProvider.fallbackResponse();
+	}
+
 	public LBC getClient() {
 		return client;
 	}