From 4c53fd2bf67626bae6822a2d2acc07e48dbe028c Mon Sep 17 00:00:00 2001
From: Dominik Mostek <mostekdominik@gmail.com>
Date: Wed, 6 Sep 2017 21:19:08 +0200
Subject: [PATCH] Fallback cause is propagated to fallback provider

Cause can now be propagated to fallback provider in order to respond accordingly to a exception type.
New interface is introduced in order not to break any existing falback providers.
---
 .../zuul/filters/route/FallbackProvider.java  |  36 +++
 .../filters/route/ZuulFallbackProvider.java   |   2 +
 .../route/support/AbstractRibbonCommand.java  |  24 +-
 ...onCommandCauseFallbackPropagationTest.java | 264 ++++++++++++++++++
 4 files changed, 324 insertions(+), 2 deletions(-)
 create mode 100644 spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/FallbackProvider.java
 create mode 100644 spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/filters/route/support/RibbonCommandCauseFallbackPropagationTest.java

diff --git a/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/FallbackProvider.java b/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/FallbackProvider.java
new file mode 100644
index 00000000..42e5ddfa
--- /dev/null
+++ b/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/FallbackProvider.java
@@ -0,0 +1,36 @@
+/*
+ * 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);
+}
diff --git a/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/ZuulFallbackProvider.java b/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/ZuulFallbackProvider.java
index d5383b52..479655f0 100644
--- a/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/ZuulFallbackProvider.java
+++ b/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 {
 
 	/**
diff --git a/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/support/AbstractRibbonCommand.java b/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/support/AbstractRibbonCommand.java
index 5431405e..eeacb4a7 100644
--- a/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/support/AbstractRibbonCommand.java
+++ b/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/zuul/filters/route/support/AbstractRibbonCommand.java
@@ -22,6 +22,7 @@ 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;
@@ -68,7 +69,13 @@ 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;
@@ -124,11 +131,24 @@ 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;
 	}
diff --git a/spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/filters/route/support/RibbonCommandCauseFallbackPropagationTest.java b/spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/filters/route/support/RibbonCommandCauseFallbackPropagationTest.java
new file mode 100644
index 00000000..b0cc25d6
--- /dev/null
+++ b/spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/zuul/filters/route/support/RibbonCommandCauseFallbackPropagationTest.java
@@ -0,0 +1,264 @@
+/*
+ * 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.support;
+
+import com.netflix.client.AbstractLoadBalancerAwareClient;
+import com.netflix.client.ClientException;
+import com.netflix.client.ClientRequest;
+import com.netflix.client.IResponse;
+import com.netflix.client.RequestSpecificRetryHandler;
+import com.netflix.client.config.IClientConfig;
+import com.netflix.client.http.HttpResponse;
+import com.netflix.hystrix.HystrixCommandProperties;
+import com.netflix.hystrix.exception.HystrixTimeoutException;
+import org.junit.Test;
+import org.springframework.cloud.netflix.zuul.filters.ZuulProperties;
+import org.springframework.cloud.netflix.zuul.filters.route.ZuulFallbackProvider;
+import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.client.ClientHttpResponse;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Dominik Mostek
+ */
+public class RibbonCommandCauseFallbackPropagationTest {
+
+    @Test
+    public void providerIsCalledInCaseOfException() throws Exception {
+        TestZuulFallbackProviderWithoutCause provider = new TestZuulFallbackProviderWithoutCause(HttpStatus.INTERNAL_SERVER_ERROR);
+        RuntimeException exception = new RuntimeException("Failed!");
+        TestRibbonCommand testCommand = new TestRibbonCommand(new TestClient(exception), provider);
+
+        ClientHttpResponse response = testCommand.execute();
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.INTERNAL_SERVER_ERROR);
+    }
+
+    @Test
+    public void causeIsProvidedForNewInterface() throws Exception {
+        TestFallbackProvider provider = TestFallbackProvider.withResponse(HttpStatus.NOT_FOUND);
+        RuntimeException exception = new RuntimeException("Failed!");
+        TestRibbonCommand testCommand = new TestRibbonCommand(new TestClient(exception), provider);
+
+        ClientHttpResponse response = testCommand.execute();
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.NOT_FOUND);
+        Throwable cause = provider.getCause();
+        assertThat(cause.getClass()).isEqualTo(exception.getClass());
+        assertThat(cause.getMessage()).isEqualTo(exception.getMessage());
+    }
+
+    @Test
+    public void executionExceptionIsUsedInsteadWhenFailedExceptionIsNull() throws Exception {
+        TestFallbackProvider provider = TestFallbackProvider.withResponse(HttpStatus.BAD_GATEWAY);
+        final RuntimeException exception = new RuntimeException("Failed!");
+        TestRibbonCommand testCommand = new TestRibbonCommand(new TestClient(exception), provider) {
+            @Override
+            public Throwable getFailedExecutionException() {
+                return null;
+            }
+
+            @Override
+            public Throwable getExecutionException() {
+                return exception;
+            }
+        };
+
+        ClientHttpResponse response = testCommand.execute();
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.BAD_GATEWAY);
+    }
+
+    @Test
+    public void timeoutExceptionIsPropagated() throws Exception {
+        TestFallbackProvider provider = TestFallbackProvider.withResponse(HttpStatus.CONFLICT);
+        RuntimeException exception = new RuntimeException("Failed!");
+        TestRibbonCommand testCommand = new TestRibbonCommand(new TestClient(exception), provider, 1) {
+            @Override
+            protected ClientRequest createRequest() throws Exception {
+                Thread.sleep(5);
+                return super.createRequest();
+            }
+        };
+
+        ClientHttpResponse response = testCommand.execute();
+
+        assertThat(response).isNotNull();
+        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.CONFLICT);
+        assertThat(provider.getCause()).isNotNull();
+        assertThat(provider.getCause().getClass()).isEqualTo(HystrixTimeoutException.class);
+    }
+
+    public static class TestRibbonCommand
+            extends AbstractRibbonCommand<AbstractLoadBalancerAwareClient<ClientRequest, HttpResponse>, ClientRequest, HttpResponse> {
+
+        public TestRibbonCommand(AbstractLoadBalancerAwareClient<ClientRequest, HttpResponse> client, ZuulFallbackProvider fallbackProvider) {
+            this(client, new ZuulProperties(), fallbackProvider);
+        }
+
+        public TestRibbonCommand(AbstractLoadBalancerAwareClient<ClientRequest, HttpResponse> client,
+                                 ZuulProperties zuulProperties,
+                                 ZuulFallbackProvider fallbackProvider) {
+            super("testCommand", client, null, zuulProperties, fallbackProvider);
+        }
+
+        public TestRibbonCommand(AbstractLoadBalancerAwareClient<ClientRequest, HttpResponse> client,
+                                 ZuulFallbackProvider fallbackProvider,
+                                 int timeout) {
+            // different name is used because of properties caching
+            super(getSetter("testCommand2", new ZuulProperties()).andCommandPropertiesDefaults(defauts(timeout)),
+                    client, null, fallbackProvider, null);
+        }
+
+        private static HystrixCommandProperties.Setter defauts(final int timeout) {
+            return HystrixCommandProperties.Setter().withExecutionTimeoutEnabled(true)
+                    .withExecutionIsolationStrategy(HystrixCommandProperties.ExecutionIsolationStrategy.THREAD)
+                    .withExecutionTimeoutInMilliseconds(timeout);
+        }
+
+        @Override
+        protected ClientRequest createRequest() throws Exception {
+            return null;
+        }
+    }
+
+    public static class TestClient extends AbstractLoadBalancerAwareClient {
+
+        private final RuntimeException exception;
+
+        public TestClient(RuntimeException exception) {
+            super(null);
+            this.exception = exception;
+        }
+
+        @Override
+        public IResponse executeWithLoadBalancer(final ClientRequest request, final IClientConfig requestConfig) throws ClientException {
+            throw exception;
+        }
+
+        @Override
+        public RequestSpecificRetryHandler getRequestSpecificRetryHandler(final ClientRequest clientRequest, final IClientConfig iClientConfig) {
+            return null;
+        }
+
+        @Override
+        public IResponse execute(final ClientRequest clientRequest, final IClientConfig iClientConfig) throws Exception {
+            return null;
+        }
+    }
+
+    public static class TestFallbackProvider implements FallbackProvider {
+
+        private final ClientHttpResponse response;
+        private Throwable cause;
+
+        public TestFallbackProvider(final ClientHttpResponse response) {
+            this.response = response;
+        }
+
+        @Override
+        public ClientHttpResponse fallbackResponse(final Throwable cause) {
+            this.cause = cause;
+            return response;
+        }
+
+        @Override
+        public String getRoute() {
+            return "test-route";
+        }
+
+        @Override
+        public ClientHttpResponse fallbackResponse() {
+            throw new UnsupportedOperationException("fallback without cause is not supported");
+        }
+
+        public Throwable getCause() {
+            return cause;
+        }
+
+        public static TestFallbackProvider withResponse(final HttpStatus status) {
+            return new TestFallbackProvider(getClientHttpResponse(status));
+        }
+    }
+
+    public static class TestZuulFallbackProviderWithoutCause implements ZuulFallbackProvider {
+
+        private final ClientHttpResponse response;
+
+        public TestZuulFallbackProviderWithoutCause(final ClientHttpResponse response) {
+            this.response = response;
+        }
+
+        public TestZuulFallbackProviderWithoutCause(final HttpStatus status) {
+            this(getClientHttpResponse(status));
+        }
+
+        @Override
+        public String getRoute() {
+            return "test-route";
+        }
+
+        @Override
+        public ClientHttpResponse fallbackResponse() {
+            return response;
+        }
+    }
+
+    private static ClientHttpResponse getClientHttpResponse(final HttpStatus status) {
+        return new ClientHttpResponse() {
+            @Override
+            public HttpStatus getStatusCode() throws IOException {
+                return status;
+            }
+
+            @Override
+            public int getRawStatusCode() throws IOException {
+                return getStatusCode().value();
+            }
+
+            @Override
+            public String getStatusText() throws IOException {
+                return getStatusCode().getReasonPhrase();
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public InputStream getBody() throws IOException {
+                return new ByteArrayInputStream("test".getBytes());
+            }
+
+            @Override
+            public HttpHeaders getHeaders() {
+                return new HttpHeaders();
+            }
+        };
+    }
+}