KNOX-2253 - Add support to handle Livy server redirects

gateway-provider-ha/src/main/java/org/apache/knox/gateway/ha/dispatch/DefaultHaDispatch.java

@@ -83,6 +83,14 @@ public void setHaProvider(HaProvider haProvider) {
     this.haProvider = haProvider;
   }
 
+  public int getMaxFailoverAttempts() {
+    return maxFailoverAttempts;
+  }
+
+  public int getFailoverSleep() {
+    return failoverSleep;
+  }
+
   @Override
   protected void executeRequest(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest, HttpServletResponse outboundResponse) throws IOException {
     HttpResponse inboundResponse = null;

gateway-provider-ha/src/main/java/org/apache/knox/gateway/ha/dispatch/i18n/HaDispatchMessages.java

@@ -30,7 +30,7 @@ public interface HaDispatchMessages {
   @Message(level = MessageLevel.INFO, text = "Could not connect to server: {0} {1}")
   void errorConnectingToServer(String uri, @StackTrace(level = MessageLevel.DEBUG) Exception e);
 
-  @Message(level = MessageLevel.INFO, text = "Failing over request to a different server: {0}")
+  @Message(level = MessageLevel.INFO, text = "Failing over request to a different server from: {0}")
   void failingOverRequest(String uri);
 
   @Message(level = MessageLevel.INFO, text = "Failed to connect to: {0}")

gateway-service-definitions/src/main/resources/services/livy/0.4.0/rewrite.xml

@@ -6,9 +6,7 @@
    The ASF licenses this file to You 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.
@@ -45,4 +43,4 @@
     <rewrite template="{$frontend[url]}/yarn/nodemanager/node/containerlogs/{**}?{scheme}?host={$hostmap(host)}?{port}"/>
   </rule>
 
-</rules>
+</rules>

gateway-service-definitions/src/main/resources/services/livy/0.4.0/service.xml

@@ -21,5 +21,5 @@
     <route path="/livy"/>
     <route path="/livy/"/>
   </routes>
-  <dispatch classname="org.apache.knox.gateway.livy.LivyDispatch"/>
+  <dispatch classname="org.apache.knox.gateway.livy.LivyDispatch" ha-classname="org.apache.knox.gateway.rm.dispatch.LivyHaDispatch"/>
 </service>

gateway-service-livy/pom.xml

@@ -30,6 +30,10 @@
     <description>The extension to the gateway for supporting Livy.</description>
 
     <dependencies>
+        <dependency>
+            <groupId>org.apache.knox</groupId>
+            <artifactId>gateway-i18n</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.apache.knox</groupId>
             <artifactId>gateway-spi</artifactId>
@@ -38,7 +42,10 @@
             <groupId>org.apache.knox</groupId>
             <artifactId>gateway-provider-rewrite</artifactId>
         </dependency>
-
+        <dependency>
+            <groupId>org.apache.knox</groupId>
+            <artifactId>gateway-provider-ha</artifactId>
+        </dependency>
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>javax.servlet-api</artifactId>

gateway-service-livy/src/main/java/org/apache/knox/gateway/livy/LivyHaDispatch.java

@@ -0,0 +1,156 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership. The ASF
+ * licenses this file to you 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.apache.knox.gateway.livy;
+
+import org.apache.http.HttpResponse;
+import org.apache.http.client.methods.HttpRequestBase;
+import org.apache.http.client.methods.HttpUriRequest;
+import org.apache.http.entity.BufferedHttpEntity;
+import org.apache.knox.gateway.ha.dispatch.DefaultHaDispatch;
+import org.apache.knox.gateway.filter.AbstractGatewayFilter;
+import org.apache.knox.gateway.i18n.messages.MessagesFactory;
+import org.apache.knox.gateway.livy.i18n.RMMessages;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.net.URI;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class  LivyHaDispatch extends DefaultHaDispatch {
+    private static final String FAILOVER_COUNTER_ATTRIBUTE = "dispatch.ha.failover.counter";
+    private static final String LOCATION = "Location";
+    private static final RMMessages LOG = MessagesFactory.get(RMMessages.class);
+    private HttpResponse inboundResponse = null;
+
+
+    public LivyHaDispatch() {
+        setServiceRole("LIVYSERVER");
+    }
+
+    /**
+     *
+     * @return HttpReponse used for unit testing so we
+     * can inject inboundResponse before calling executeRequest method
+     */
+    private HttpResponse getInboundResponse() {
+        HttpResponse response = this.inboundResponse;
+        this.setInboundResponse(null);
+        return response;
+    }
+
+    void setInboundResponse(HttpResponse inboundResponse) {
+        this.inboundResponse = inboundResponse;
+    }
+
+    @Override
+    protected void executeRequest(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest, HttpServletResponse outboundResponse) throws IOException {
+        HttpResponse inboundResponse = this.getInboundResponse();
+        try {
+           if( this.getInboundResponse() == null ) {
+             inboundResponse = executeOutboundRequest(outboundRequest);
+           }
+           writeOutboundResponse(outboundRequest, inboundRequest, outboundResponse, inboundResponse);
+        } catch (StandbyException e) {
+           LOG.errorReceivedFromStandbyNode(e);
+           failoverRequest(outboundRequest, inboundRequest, outboundResponse, inboundResponse, e);
+        } catch (IOException e) {
+           LOG.errorConnectingToServer(outboundRequest.getURI().toString(), e);
+           failoverRequest(outboundRequest, inboundRequest, outboundResponse, inboundResponse, e);
+        }
+     }
+
+    /**
+     * Checks for specific outbound response codes/content to trigger a retry or failover
+     */
+    @Override
+    protected void writeOutboundResponse(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest, HttpServletResponse outboundResponse, HttpResponse inboundResponse) throws IOException {
+       int status = inboundResponse.getStatusLine().getStatusCode();
+       if ( status  == 403 || status == 307) {
+          BufferedHttpEntity entity = new BufferedHttpEntity(inboundResponse.getEntity());
+          inboundResponse.setEntity(entity);
+          ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+          inboundResponse.getEntity().writeTo(outputStream);
+          String body = new String(outputStream.toByteArray(), StandardCharsets.UTF_8);
+          if (body.contains("This is a standby Livy Instance")) {
+             throw new StandbyException();
+          }
+       }
+       super.writeOutboundResponse(outboundRequest, inboundRequest, outboundResponse, inboundResponse);
+    }
+
+    @Override
+    protected void failoverRequest(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest, HttpServletResponse outboundResponse, HttpResponse inboundResponse, Exception exception) throws IOException {
+       LOG.failingOverRequest(outboundRequest.getURI().toString());
+       URI uri;
+       String outboundURIs;
+       AtomicInteger counter = (AtomicInteger) inboundRequest.getAttribute(FAILOVER_COUNTER_ATTRIBUTE);
+       if (counter == null) {
+          counter = new AtomicInteger(0);
+       }
+       inboundRequest.setAttribute(FAILOVER_COUNTER_ATTRIBUTE, counter);
+       outboundURIs = outboundRequest.getURI().toString();
+
+       if (counter.incrementAndGet() <= getMaxFailoverAttempts()) {
+          //null out target url so that rewriters run again
+          inboundRequest.setAttribute(AbstractGatewayFilter.TARGET_REQUEST_URL_ATTRIBUTE_NAME, null);
+
+           uri = getUriFromInbound(inboundRequest, inboundResponse, outboundURIs);
+           ((HttpRequestBase) outboundRequest).setURI(uri);
+          if (getFailoverSleep() > 0) {
+             try {
+                Thread.sleep(getFailoverSleep());
+             } catch (InterruptedException e) {
+                LOG.failoverSleepFailed(getServiceRole(), e);
+             }
+          }
+          executeRequest(outboundRequest, inboundRequest, outboundResponse);
+       } else {
+          LOG.maxFailoverAttemptsReached(getMaxFailoverAttempts(), getServiceRole());
+          if (inboundResponse != null) {
+             writeOutboundResponse(outboundRequest, inboundRequest, outboundResponse, inboundResponse);
+          } else {
+             throw new IOException(exception);
+          }
+       }
+    }
+
+    URI getUriFromInbound(HttpServletRequest inboundRequest, HttpResponse inboundResponse, String outboundURIs) {
+         URI uri;
+         if( outboundURIs != null ) {
+             getHaProvider().markFailedURL(getServiceRole(), outboundURIs);
+         }
+         try {
+            if( inboundResponse != null ) {
+               // We get redirection URI, failover condition we don't
+               // need to consult list of host.
+               String host = inboundResponse.getFirstHeader(LOCATION).getValue();
+               LOG.failoverRedirect(host);
+               uri = URI.create(host);
+            } else { // inboundRequest was null previous active node is down
+                     // get next URI in list to try.
+               uri = getDispatchUrl(inboundRequest);
+            }
+         } catch(Exception ex ) {
+            uri = getDispatchUrl(inboundRequest);
+         }
+         getHaProvider().setActiveURL(getServiceRole(), uri.toString());
+         return uri;
+     }
+}

gateway-service-livy/src/main/java/org/apache/knox/gateway/livy/StandbyException.java

@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.apache.knox.gateway.livy;
+
+class StandbyException extends RuntimeException {
+}

gateway-service-livy/src/main/java/org/apache/knox/gateway/livy/i18n/RMMessages.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.knox.gateway.livy.i18n;
+
+import org.apache.knox.gateway.ha.dispatch.i18n.HaDispatchMessages;
+import org.apache.knox.gateway.i18n.messages.Message;
+import org.apache.knox.gateway.i18n.messages.MessageLevel;
+import org.apache.knox.gateway.i18n.messages.Messages;
+import org.apache.knox.gateway.i18n.messages.StackTrace;
+
+@Messages(logger = "org.apache.knox.gateway")
+public interface RMMessages extends HaDispatchMessages {
+
+  @Message(level = MessageLevel.WARN, text = "Received an error from a Livy Server in Standby: {0}")
+   void errorReceivedFromStandbyNode(@StackTrace(level = MessageLevel.DEBUG) Exception e);
+
+  @Message(level = MessageLevel.WARN, text = "Redirect to {0} because of accessing standby Livy Server.")
+   void failoverRedirect(String redirect);
+}