HDFS-5122. Merge change r1524562 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1524566 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -125,6 +125,9 @@ Release 2.1.1-beta - 2013-09-23
 
     HDFS-5199 Add more debug trace for NFS READ and WRITE. (brandonli)
 
+    HDFS-5122. Support failover and retry in WebHdfsFileSystem for NN HA.
+    (Haohui Mai via jing9)
+
   IMPROVEMENTS
 
     HDFS-4513. Clarify in the WebHDFS REST API that all JSON respsonses may

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java

@@ -38,6 +38,7 @@ import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.security.SecureRandom;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
@@ -600,6 +601,48 @@ public class DFSUtil {
     return getAddresses(conf, null, DFSConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY);
   }
 
+  /**
+   * Returns list of InetSocketAddress corresponding to HA NN HTTP addresses from
+   * the configuration.
+   *
+   * @param conf configuration
+   * @return list of InetSocketAddresses
+   */
+  public static Map<String, Map<String, InetSocketAddress>> getHaNnHttpAddresses(
+      Configuration conf) {
+    return getAddresses(conf, null, DFSConfigKeys.DFS_NAMENODE_HTTP_ADDRESS_KEY);
+  }
+
+  /**
+   * Resolve an HDFS URL into real INetSocketAddress. It works like a DNS resolver
+   * when the URL points to an non-HA cluster. When the URL points to an HA
+   * cluster, the resolver further resolves the logical name (i.e., the authority
+   * in the URL) into real namenode addresses.
+   */
+  public static InetSocketAddress[] resolve(URI uri, int schemeDefaultPort,
+      Configuration conf) throws IOException {
+    ArrayList<InetSocketAddress> ret = new ArrayList<InetSocketAddress>();
+
+    if (!HAUtil.isLogicalUri(conf, uri)) {
+      InetSocketAddress addr = NetUtils.createSocketAddr(uri.getAuthority(),
+          schemeDefaultPort);
+      ret.add(addr);
+
+    } else {
+      Map<String, Map<String, InetSocketAddress>> addresses = DFSUtil
+          .getHaNnHttpAddresses(conf);
+
+      for (Map<String, InetSocketAddress> addrs : addresses.values()) {
+        for (InetSocketAddress addr : addrs.values()) {
+          ret.add(addr);
+        }
+      }
+    }
+
+    InetSocketAddress[] r = new InetSocketAddress[ret.size()];
+    return ret.toArray(r);
+  }
+  
   /**
    * Returns list of InetSocketAddress corresponding to  backup node rpc 
    * addresses from the configuration.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -54,6 +54,7 @@ import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.ByteRangeInputStream;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.hdfs.HAUtil;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
@@ -86,6 +87,7 @@ import org.apache.hadoop.hdfs.web.resources.ReplicationParam;
 import org.apache.hadoop.hdfs.web.resources.TokenArgumentParam;
 import org.apache.hadoop.hdfs.web.resources.UserParam;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.retry.RetryPolicies;
 import org.apache.hadoop.io.retry.RetryPolicy;
 import org.apache.hadoop.io.retry.RetryUtils;
 import org.apache.hadoop.ipc.RemoteException;
@@ -121,7 +123,7 @@ public class WebHdfsFileSystem extends FileSystem
 
   /** SPNEGO authenticator */
   private static final KerberosUgiAuthenticator AUTH = new KerberosUgiAuthenticator();
-  /** Default connection factory may be overriden in tests to use smaller timeout values */
+  /** Default connection factory may be overridden in tests to use smaller timeout values */
   URLConnectionFactory connectionFactory = URLConnectionFactory.DEFAULT_CONNECTION_FACTORY;
   /** Configures connections for AuthenticatedURL */
   private final ConnectionConfigurator CONN_CONFIGURATOR =
@@ -161,12 +163,13 @@ public class WebHdfsFileSystem extends FileSystem
   }
 
   private UserGroupInformation ugi;
-  private InetSocketAddress nnAddr;
   private URI uri;
   private boolean hasInitedToken;
   private Token<?> delegationToken;
   private RetryPolicy retryPolicy = null;
   private Path workingDir;
+  private InetSocketAddress nnAddrs[];
+  private int currentNNAddrIndex;
 
   /**
    * Return the protocol scheme for the FileSystem.
@@ -176,7 +179,7 @@ public class WebHdfsFileSystem extends FileSystem
    */
   @Override
   public String getScheme() {
-    return "webhdfs";
+    return SCHEME;
   }
 
   @Override
@@ -185,20 +188,42 @@ public class WebHdfsFileSystem extends FileSystem
     super.initialize(uri, conf);
     setConf(conf);
     ugi = UserGroupInformation.getCurrentUser();
+
     try {
-      this.uri = new URI(uri.getScheme(), uri.getAuthority(), null, null, null);
+      this.uri = new URI(uri.getScheme(), uri.getAuthority(), null,
+          null, null);
+      this.nnAddrs = DFSUtil.resolve(this.uri, getDefaultPort(), conf);
     } catch (URISyntaxException e) {
       throw new IllegalArgumentException(e);
     }
-    this.nnAddr = NetUtils.createSocketAddr(uri.getAuthority(), getDefaultPort());
+
-    this.retryPolicy = 
+    if (!HAUtil.isLogicalUri(conf, this.uri)) {
-        RetryUtils.getDefaultRetryPolicy(
+      this.retryPolicy =
-            conf, 
+          RetryUtils.getDefaultRetryPolicy(
-            DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_KEY,
+              conf,
-            DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_DEFAULT,
+              DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_KEY,
-            DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_KEY,
+              DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_ENABLED_DEFAULT,
-            DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_DEFAULT,
+              DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_KEY,
-            SafeModeException.class);
+              DFSConfigKeys.DFS_HTTP_CLIENT_RETRY_POLICY_SPEC_DEFAULT,
+              SafeModeException.class);
+    } else {
+
+      int maxFailoverAttempts = conf.getInt(
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_MAX_ATTEMPTS_KEY,
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_MAX_ATTEMPTS_DEFAULT);
+      int failoverSleepBaseMillis = conf.getInt(
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_BASE_KEY,
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT);
+      int failoverSleepMaxMillis = conf.getInt(
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_MAX_KEY,
+          DFSConfigKeys.DFS_HTTP_CLIENT_FAILOVER_SLEEPTIME_MAX_DEFAULT);
+
+      this.retryPolicy = RetryPolicies
+          .failoverOnNetworkException(RetryPolicies.TRY_ONCE_THEN_FAIL,
+              maxFailoverAttempts, failoverSleepBaseMillis,
+              failoverSleepMaxMillis);
+    }
+
     this.workingDir = getHomeDirectory();
 
     if (UserGroupInformation.isSecurityEnabled()) {
@@ -350,6 +375,19 @@ public class WebHdfsFileSystem extends FileSystem
     return ((RemoteException)ioe).unwrapRemoteException();
   }
 
+  private synchronized InetSocketAddress getCurrentNNAddr() {
+    return nnAddrs[currentNNAddrIndex];
+  }
+
+  /**
+   * Reset the appropriate state to gracefully fail over to another name node
+   */
+  private synchronized void resetStateToFailOver() {
+    currentNNAddrIndex = (currentNNAddrIndex + 1) % nnAddrs.length;
+    delegationToken = null;
+    hasInitedToken = false;
+  }
+
   /**
    * Return a URL pointing to given path on the namenode.
    *
@@ -359,6 +397,7 @@ public class WebHdfsFileSystem extends FileSystem
    * @throws IOException on error constructing the URL
    */
   private URL getNamenodeURL(String path, String query) throws IOException {
+    InetSocketAddress nnAddr = getCurrentNNAddr();
     final URL url = new URL("http", nnAddr.getHostName(),
           nnAddr.getPort(), path + '?' + query);
     if (LOG.isTraceEnabled()) {
@@ -416,38 +455,28 @@ public class WebHdfsFileSystem extends FileSystem
    */
   private Map<?, ?> run(final HttpOpParam.Op op, final Path fspath,
       final Param<?,?>... parameters) throws IOException {
-    return new Runner(op, fspath, parameters).run().json;
+    return new FsPathRunner(op, fspath, parameters).run().json;
   }
 
   /**
    * This class is for initialing a HTTP connection, connecting to server,
    * obtaining a response, and also handling retry on failures.
    */
-  class Runner {
+  abstract class AbstractRunner {
-    private final HttpOpParam.Op op;
+    abstract protected URL getUrl() throws IOException;
-    private final URL url;
+
+    protected final HttpOpParam.Op op;
     private final boolean redirected;
 
     private boolean checkRetry;
-    private HttpURLConnection conn = null;
+    protected HttpURLConnection conn = null;
     private Map<?, ?> json = null;
 
-    Runner(final HttpOpParam.Op op, final URL url, final boolean redirected) {
+    protected AbstractRunner(final HttpOpParam.Op op, boolean redirected) {
       this.op = op;
-      this.url = url;
       this.redirected = redirected;
     }
 
-    Runner(final HttpOpParam.Op op, final Path fspath,
-        final Param<?,?>... parameters) throws IOException {
-      this(op, toUrl(op, fspath, parameters), false);
-    }
-
-    Runner(final HttpOpParam.Op op, final HttpURLConnection conn) {
-      this(op, null, false);
-      this.conn = conn;
-    }
-
     private HttpURLConnection getHttpUrlConnection(final URL url)
         throws IOException, AuthenticationException {
       UserGroupInformation connectUgi = ugi.getRealUser();
@@ -495,6 +524,7 @@ public class WebHdfsFileSystem extends FileSystem
   
     private void init() throws IOException {
       checkRetry = !redirected;
+      URL url = getUrl();
       try {
         conn = getHttpUrlConnection(url);
       } catch(AuthenticationException ae) {
@@ -521,7 +551,23 @@ public class WebHdfsFileSystem extends FileSystem
       }
     }
 
-    Runner run() throws IOException {
+    AbstractRunner run() throws IOException {
+      /**
+       * Do the real work.
+       *
+       * There are three cases that the code inside the loop can throw an
+       * IOException:
+       *
+       * <ul>
+       * <li>The connection has failed (e.g., ConnectException,
+       * @see FailoverOnNetworkExceptionRetry for more details)</li>
+       * <li>The namenode enters the standby state (i.e., StandbyException).</li>
+       * <li>The server returns errors for the command (i.e., RemoteException)</li>
+       * </ul>
+       *
+       * The call to shouldRetry() will conduct the retry policy. The policy
+       * examines the exception and swallows it if it decides to rerun the work.
+       */
       for(int retry = 0; ; retry++) {
         try {
           init();
@@ -539,14 +585,25 @@ public class WebHdfsFileSystem extends FileSystem
 
     private void shouldRetry(final IOException ioe, final int retry
         ) throws IOException {
+      InetSocketAddress nnAddr = getCurrentNNAddr();
       if (checkRetry) {
         try {
           final RetryPolicy.RetryAction a = retryPolicy.shouldRetry(
               ioe, retry, 0, true);
-          if (a.action == RetryPolicy.RetryAction.RetryDecision.RETRY) {
+
+          boolean isRetry = a.action == RetryPolicy.RetryAction.RetryDecision.RETRY;
+          boolean isFailoverAndRetry =
+              a.action == RetryPolicy.RetryAction.RetryDecision.FAILOVER_AND_RETRY;
+
+          if (isRetry || isFailoverAndRetry) {
             LOG.info("Retrying connect to namenode: " + nnAddr
                 + ". Already tried " + retry + " time(s); retry policy is "
                 + retryPolicy + ", delay " + a.delayMillis + "ms.");
+
+            if (isFailoverAndRetry) {
+              resetStateToFailOver();
+            }
+
             Thread.sleep(a.delayMillis);
             return;
           }
@@ -619,6 +676,48 @@ public class WebHdfsFileSystem extends FileSystem
     }
   }
 
+  final class FsPathRunner extends AbstractRunner {
+    private final Path fspath;
+    private final Param<?, ?>[] parameters;
+
+    FsPathRunner(final HttpOpParam.Op op, final Path fspath, final Param<?,?>... parameters) {
+      super(op, false);
+      this.fspath = fspath;
+      this.parameters = parameters;
+    }
+
+    @Override
+    protected URL getUrl() throws IOException {
+      return toUrl(op, fspath, parameters);
+    }
+  }
+
+  final class URLRunner extends AbstractRunner {
+    private final URL url;
+    @Override
+    protected URL getUrl() {
+      return url;
+    }
+
+    protected URLRunner(final HttpOpParam.Op op, final URL url, boolean redirected) {
+      super(op, redirected);
+      this.url = url;
+    }
+  }
+
+  @VisibleForTesting
+  final class ConnRunner extends AbstractRunner {
+    protected ConnRunner(final HttpOpParam.Op op, HttpURLConnection conn) {
+      super(op, false);
+      this.conn = conn;
+    }
+
+    @Override
+    protected URL getUrl() {
+      return null;
+    }
+  }
+
   private FsPermission applyUMask(FsPermission permission) {
     if (permission == null) {
       permission = FsPermission.getDefault();
@@ -774,7 +873,7 @@ public class WebHdfsFileSystem extends FileSystem
     statistics.incrementWriteOps(1);
 
     final HttpOpParam.Op op = PutOpParam.Op.CREATE;
-    return new Runner(op, f, 
+    return new FsPathRunner(op, f,
         new PermissionParam(applyUMask(permission)),
         new OverwriteParam(overwrite),
         new BufferSizeParam(bufferSize),
@@ -790,7 +889,7 @@ public class WebHdfsFileSystem extends FileSystem
     statistics.incrementWriteOps(1);
 
     final HttpOpParam.Op op = PostOpParam.Op.APPEND;
-    return new Runner(op, f, new BufferSizeParam(bufferSize))
+    return new FsPathRunner(op, f, new BufferSizeParam(bufferSize))
       .run()
       .write(bufferSize);
   }
@@ -837,7 +936,7 @@ public class WebHdfsFileSystem extends FileSystem
         final boolean resolved) throws IOException {
       final URL offsetUrl = offset == 0L? url
           : new URL(url + "&" + new OffsetParam(offset));
-      return new Runner(GetOpParam.Op.OPEN, offsetUrl, resolved).run().conn;
+      return new URLRunner(GetOpParam.Op.OPEN, offsetUrl, resolved).run().conn;
     }  
   }
 
@@ -911,7 +1010,7 @@ public class WebHdfsFileSystem extends FileSystem
     final HttpOpParam.Op op = GetOpParam.Op.GETDELEGATIONTOKEN;
     final Map<?, ?> m = run(op, null, new RenewerParam(renewer));
     final Token<DelegationTokenIdentifier> token = JsonUtil.toDelegationToken(m); 
-    SecurityUtil.setTokenService(token, nnAddr);
+    SecurityUtil.setTokenService(token, getCurrentNNAddr());
     return token;
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSUtil.java

@@ -20,20 +20,25 @@ package org.apache.hadoop.hdfs;
 
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.FS_DEFAULT_NAME_KEY;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_AUTHENTICATION;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_FAILOVER_PROXY_PROVIDER_KEY_PREFIX;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_HA_NAMENODES_KEY_PREFIX;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_BACKUP_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_HTTPS_PORT_DEFAULT;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_HTTP_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_HTTP_PORT_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_RPC_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_SERVICE_RPC_ADDRESS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMESERVICES;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMESERVICE_ID;
-import org.apache.hadoop.util.Shell;
+import static org.hamcrest.CoreMatchers.not;
-
+import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertEquals;
-import org.junit.Assume;
+import static org.junit.Assert.assertFalse;
-import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.io.IOException;
 import java.net.InetSocketAddress;
@@ -54,8 +59,11 @@ import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
+import org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.util.Shell;
+import org.junit.Assume;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -539,6 +547,55 @@ public class TestDFSUtil {
     assertEquals("ns1", DFSUtil.getSecondaryNameServiceId(conf));
   }
 
+  @Test
+  public void testGetHaNnHttpAddresses() throws IOException {
+    final String LOGICAL_HOST_NAME = "ns1";
+    final String NS1_NN1_ADDR      = "ns1-nn1.example.com:8020";
+    final String NS1_NN2_ADDR      = "ns1-nn2.example.com:8020";
+
+    Configuration conf = createWebHDFSHAConfiguration(LOGICAL_HOST_NAME, NS1_NN1_ADDR, NS1_NN2_ADDR);
+
+    Map<String, Map<String, InetSocketAddress>> map =
+        DFSUtil.getHaNnHttpAddresses(conf);
+
+    assertEquals(NS1_NN1_ADDR, map.get("ns1").get("nn1").toString());
+    assertEquals(NS1_NN2_ADDR, map.get("ns1").get("nn2").toString());
+  }
+
+  @Test
+  public void testResolve() throws IOException, URISyntaxException {
+    final String LOGICAL_HOST_NAME = "ns1";
+    final String NS1_NN1_HOST      = "ns1-nn1.example.com";
+    final String NS1_NN2_HOST      = "ns1-nn2.example.com";
+    final String NS1_NN1_ADDR      = "ns1-nn1.example.com:8020";
+    final String NS1_NN2_ADDR      = "ns1-nn2.example.com:8020";
+    final int DEFAULT_PORT         = NameNode.DEFAULT_PORT;
+
+    Configuration conf = createWebHDFSHAConfiguration(LOGICAL_HOST_NAME, NS1_NN1_ADDR, NS1_NN2_ADDR);
+    URI uri = new URI("webhdfs://ns1");
+    assertTrue(HAUtil.isLogicalUri(conf, uri));
+    InetSocketAddress[] addrs = DFSUtil.resolve(uri, DEFAULT_PORT, conf);
+    assertArrayEquals(new InetSocketAddress[] {
+      new InetSocketAddress(NS1_NN1_HOST, DEFAULT_PORT),
+      new InetSocketAddress(NS1_NN2_HOST, DEFAULT_PORT),
+    }, addrs);
+  }
+
+  private static Configuration createWebHDFSHAConfiguration(String logicalHostName, String nnaddr1, String nnaddr2) {
+    HdfsConfiguration conf = new HdfsConfiguration();
+
+    conf.set(DFS_NAMESERVICES, "ns1");
+    conf.set(DFSUtil.addKeySuffixes(DFS_HA_NAMENODES_KEY_PREFIX, "ns1"),"nn1,nn2");
+    conf.set(DFSUtil.addKeySuffixes(
+        DFS_NAMENODE_HTTP_ADDRESS_KEY, "ns1", "nn1"), nnaddr1);
+    conf.set(DFSUtil.addKeySuffixes(
+        DFS_NAMENODE_HTTP_ADDRESS_KEY, "ns1", "nn2"), nnaddr2);
+
+    conf.set(DFS_CLIENT_FAILOVER_PROXY_PROVIDER_KEY_PREFIX + "." + logicalHostName,
+        ConfiguredFailoverProxyProvider.class.getName());
+    return conf;
+  }
+
   @Test
   public void testSubstituteForWildcardAddress() throws IOException {
     assertEquals("foo:12345",

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHDFSForHA.java

@@ -0,0 +1,77 @@
+/**
+ * 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.hadoop.hdfs.web;
+
+import java.net.URI;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.MiniDFSNNTopology;
+import org.apache.hadoop.hdfs.server.namenode.ha.HATestUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+/** Test whether WebHDFS can connect to an HA cluster */
+public class TestWebHDFSForHA {
+
+  private static final String LOGICAL_NAME = "minidfs";
+
+  @Test
+  public void test() throws Exception {
+    Configuration conf = new Configuration();
+    conf.setBoolean(DFSConfigKeys.DFS_WEBHDFS_ENABLED_KEY, true);
+
+    MiniDFSNNTopology topo = new MiniDFSNNTopology()
+        .addNameservice(new MiniDFSNNTopology.NSConf(LOGICAL_NAME).addNN(
+            new MiniDFSNNTopology.NNConf("nn1")).addNN(
+            new MiniDFSNNTopology.NNConf("nn2")));
+
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf).nnTopology(topo)
+        .numDataNodes(3).build();
+
+    HATestUtil.setFailoverConfigurations(cluster, conf, LOGICAL_NAME);
+
+    FileSystem fs = null;
+    try {
+      cluster.waitActive();
+
+      final String uri = WebHdfsFileSystem.SCHEME + "://" + LOGICAL_NAME;
+      fs = (WebHdfsFileSystem) FileSystem.get(new URI(uri), conf);
+      cluster.transitionToActive(0);
+
+      final Path dir = new Path("/test");
+      Assert.assertTrue(fs.mkdirs(dir));
+
+      cluster.shutdownNameNode(0);
+      cluster.transitionToActive(1);
+
+      final Path dir2 = new Path("/test2");
+      Assert.assertTrue(fs.mkdirs(dir2));
+
+    } finally {
+      if (fs != null) {
+        fs.close();
+      }
+      cluster.shutdown();
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/WebHdfsTestUtil.java

@@ -81,7 +81,7 @@ public class WebHdfsTestUtil {
   
   public static HttpURLConnection twoStepWrite(final WebHdfsFileSystem webhdfs,
       final HttpOpParam.Op op, HttpURLConnection conn) throws IOException {
-    return webhdfs.new Runner(op, conn).twoStepWrite();
+    return webhdfs.new ConnRunner(op, conn).twoStepWrite();
   }
 
   public static FSDataOutputStream write(final WebHdfsFileSystem webhdfs,