HDFS-14545. RBF: Router should support GetUserMappingsProtocol. Contributed by Ayush Saxena.

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/ConnectionPool.java

@@ -18,8 +18,10 @@
 package org.apache.hadoop.hdfs.server.federation.router;
 
 import java.io.IOException;
+import java.lang.reflect.Constructor;
 import java.net.InetSocketAddress;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
 import java.util.List;
@@ -48,9 +50,15 @@ import org.apache.hadoop.io.retry.RetryUtils;
 import org.apache.hadoop.ipc.ProtobufRpcEngine;
 import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.security.RefreshUserMappingsProtocol;
 import org.apache.hadoop.security.SaslRpcServer;
 import org.apache.hadoop.security.SecurityUtil;
 import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.protocolPB.RefreshUserMappingsProtocolClientSideTranslatorPB;
+import org.apache.hadoop.security.protocolPB.RefreshUserMappingsProtocolPB;
+import org.apache.hadoop.tools.GetUserMappingsProtocol;
+import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolClientSideTranslatorPB;
+import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolPB;
 import org.apache.hadoop.util.Time;
 import org.eclipse.jetty.util.ajax.JSON;
 import org.slf4j.Logger;
@@ -97,6 +105,32 @@ public class ConnectionPool {
   /** The last time a connection was active. */
   private volatile long lastActiveTime = 0;
 
+  /** Map for the protocols and their protobuf implementations. */
+  private final static Map<Class<?>, ProtoImpl> PROTO_MAP = new HashMap<>();
+  static {
+    PROTO_MAP.put(ClientProtocol.class,
+        new ProtoImpl(ClientNamenodeProtocolPB.class,
+            ClientNamenodeProtocolTranslatorPB.class));
+    PROTO_MAP.put(NamenodeProtocol.class, new ProtoImpl(
+        NamenodeProtocolPB.class, NamenodeProtocolTranslatorPB.class));
+    PROTO_MAP.put(RefreshUserMappingsProtocol.class,
+        new ProtoImpl(RefreshUserMappingsProtocolPB.class,
+            RefreshUserMappingsProtocolClientSideTranslatorPB.class));
+    PROTO_MAP.put(GetUserMappingsProtocol.class,
+        new ProtoImpl(GetUserMappingsProtocolPB.class,
+            GetUserMappingsProtocolClientSideTranslatorPB.class));
+  }
+
+  /** Class to store the protocol implementation. */
+  private static class ProtoImpl {
+    private final Class<?> protoPb;
+    private final Class<?> protoClientPb;
+
+    ProtoImpl(Class<?> pPb, Class<?> pClientPb) {
+      this.protoPb = pPb;
+      this.protoClientPb = pClientPb;
+    }
+  }
 
   protected ConnectionPool(Configuration config, String address,
       UserGroupInformation user, int minPoolSize, int maxPoolSize,
@@ -325,6 +359,7 @@ public class ConnectionPool {
    * context for a single user/security context. To maximize throughput it is
    * recommended to use multiple connection per user+server, allowing multiple
    * writes and reads to be dispatched in parallel.
+   * @param <T>
    *
    * @param conf Configuration for the connection.
    * @param nnAddress Address of server supporting the ClientProtocol.
@@ -334,47 +369,19 @@ public class ConnectionPool {
    *         security context.
    * @throws IOException If it cannot be created.
    */
-  protected static ConnectionContext newConnection(Configuration conf,
+  protected static <T> ConnectionContext newConnection(Configuration conf,
-      String nnAddress, UserGroupInformation ugi, Class<?> proto)
+      String nnAddress, UserGroupInformation ugi, Class<T> proto)
-          throws IOException {
+      throws IOException {
-    ConnectionContext ret;
+    if (!PROTO_MAP.containsKey(proto)) {
-    if (proto == ClientProtocol.class) {
+      String msg = "Unsupported protocol for connection to NameNode: "
-      ret = newClientConnection(conf, nnAddress, ugi);
+          + ((proto != null) ? proto.getClass().getName() : "null");
-    } else if (proto == NamenodeProtocol.class) {
-      ret = newNamenodeConnection(conf, nnAddress, ugi);
-    } else {
-      String msg = "Unsupported protocol for connection to NameNode: " +
-          ((proto != null) ? proto.getClass().getName() : "null");
       LOG.error(msg);
       throw new IllegalStateException(msg);
     }
-    return ret;
+    ProtoImpl classes = PROTO_MAP.get(proto);
-  }
+    RPC.setProtocolEngine(conf, classes.protoPb, ProtobufRpcEngine.class);
 
-  /**
+    final RetryPolicy defaultPolicy = RetryUtils.getDefaultRetryPolicy(conf,
-   * Creates a proxy wrapper for a client NN connection. Each proxy contains
-   * context for a single user/security context. To maximize throughput it is
-   * recommended to use multiple connection per user+server, allowing multiple
-   * writes and reads to be dispatched in parallel.
-   *
-   * Mostly based on NameNodeProxies#createNonHAProxy() but it needs the
-   * connection identifier.
-   *
-   * @param conf Configuration for the connection.
-   * @param nnAddress Address of server supporting the ClientProtocol.
-   * @param ugi User context.
-   * @return Proxy for the target ClientProtocol that contains the user's
-   *         security context.
-   * @throws IOException If it cannot be created.
-   */
-  private static ConnectionContext newClientConnection(
-      Configuration conf, String nnAddress, UserGroupInformation ugi)
-          throws IOException {
-    RPC.setProtocolEngine(
-        conf, ClientNamenodeProtocolPB.class, ProtobufRpcEngine.class);
-
-    final RetryPolicy defaultPolicy = RetryUtils.getDefaultRetryPolicy(
-        conf,
         HdfsClientConfigKeys.Retry.POLICY_ENABLED_KEY,
         HdfsClientConfigKeys.Retry.POLICY_ENABLED_DEFAULT,
         HdfsClientConfigKeys.Retry.POLICY_SPEC_KEY,
@@ -386,61 +393,32 @@ public class ConnectionPool {
       SaslRpcServer.init(conf);
     }
     InetSocketAddress socket = NetUtils.createSocketAddr(nnAddress);
-    final long version = RPC.getProtocolVersion(ClientNamenodeProtocolPB.class);
+    final long version = RPC.getProtocolVersion(classes.protoPb);
-    ClientNamenodeProtocolPB proxy = RPC.getProtocolProxy(
+    Object proxy = RPC.getProtocolProxy(classes.protoPb, version, socket, ugi,
-        ClientNamenodeProtocolPB.class, version, socket, ugi, conf,
+        conf, factory, RPC.getRpcTimeout(conf), defaultPolicy, null).getProxy();
-        factory, RPC.getRpcTimeout(conf), defaultPolicy, null).getProxy();
+    T client = newProtoClient(proto, classes, proxy);
-    ClientProtocol client = new ClientNamenodeProtocolTranslatorPB(proxy);
     Text dtService = SecurityUtil.buildTokenService(socket);
 
-    ProxyAndInfo<ClientProtocol> clientProxy =
+    ProxyAndInfo<T> clientProxy =
-        new ProxyAndInfo<ClientProtocol>(client, dtService, socket);
+        new ProxyAndInfo<T>(client, dtService, socket);
     ConnectionContext connection = new ConnectionContext(clientProxy);
     return connection;
   }
 
-  /**
+  private static <T> T newProtoClient(Class<T> proto, ProtoImpl classes,
-   * Creates a proxy wrapper for a NN connection. Each proxy contains context
+      Object proxy) {
-   * for a single user/security context. To maximize throughput it is
+    try {
-   * recommended to use multiple connection per user+server, allowing multiple
+      Constructor<?> constructor =
-   * writes and reads to be dispatched in parallel.
+          classes.protoClientPb.getConstructor(classes.protoPb);
-   *
+      Object o = constructor.newInstance(new Object[] {proxy});
-   * @param conf Configuration for the connection.
+      if (proto.isAssignableFrom(o.getClass())) {
-   * @param nnAddress Address of server supporting the ClientProtocol.
+        @SuppressWarnings("unchecked")
-   * @param ugi User context.
+        T client = (T) o;
-   * @return Proxy for the target NamenodeProtocol that contains the user's
+        return client;
-   *         security context.
+      }
-   * @throws IOException If it cannot be created.
+    } catch (Exception e) {
-   */
+      LOG.error(e.getMessage());
-  private static ConnectionContext newNamenodeConnection(
-      Configuration conf, String nnAddress, UserGroupInformation ugi)
-          throws IOException {
-    RPC.setProtocolEngine(
-        conf, NamenodeProtocolPB.class, ProtobufRpcEngine.class);
-
-    final RetryPolicy defaultPolicy = RetryUtils.getDefaultRetryPolicy(
-        conf,
-        HdfsClientConfigKeys.Retry.POLICY_ENABLED_KEY,
-        HdfsClientConfigKeys.Retry.POLICY_ENABLED_DEFAULT,
-        HdfsClientConfigKeys.Retry.POLICY_SPEC_KEY,
-        HdfsClientConfigKeys.Retry.POLICY_SPEC_DEFAULT,
-        HdfsConstants.SAFEMODE_EXCEPTION_CLASS_NAME);
-
-    SocketFactory factory = SocketFactory.getDefault();
-    if (UserGroupInformation.isSecurityEnabled()) {
-      SaslRpcServer.init(conf);
     }
-    InetSocketAddress socket = NetUtils.createSocketAddr(nnAddress);
+    return null;
-    final long version = RPC.getProtocolVersion(NamenodeProtocolPB.class);
-    NamenodeProtocolPB proxy = RPC.getProtocolProxy(NamenodeProtocolPB.class,
-        version, socket, ugi, conf,
-        factory, RPC.getRpcTimeout(conf), defaultPolicy, null).getProxy();
-    NamenodeProtocol client = new NamenodeProtocolTranslatorPB(proxy);
-    Text dtService = SecurityUtil.buildTokenService(socket);
-
-    ProxyAndInfo<NamenodeProtocol> clientProxy =
-        new ProxyAndInfo<NamenodeProtocol>(client, dtService, socket);
-    ConnectionContext connection = new ConnectionContext(clientProxy);
-    return connection;
   }
 }

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java

@@ -139,15 +139,17 @@ import org.apache.hadoop.ipc.RetriableException;
 import org.apache.hadoop.ipc.StandbyException;
 import org.apache.hadoop.net.NodeBase;
 import org.apache.hadoop.security.AccessControlException;
-import org.apache.hadoop.security.Groups;
 import org.apache.hadoop.security.RefreshUserMappingsProtocol;
 import org.apache.hadoop.security.UserGroupInformation;
-import org.apache.hadoop.security.authorize.ProxyUsers;
 import org.apache.hadoop.security.proto.RefreshUserMappingsProtocolProtos;
 import org.apache.hadoop.security.protocolPB.RefreshUserMappingsProtocolPB;
 import org.apache.hadoop.security.protocolPB.RefreshUserMappingsProtocolServerSideTranslatorPB;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.service.AbstractService;
+import org.apache.hadoop.tools.GetUserMappingsProtocol;
+import org.apache.hadoop.tools.proto.GetUserMappingsProtocolProtos;
+import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolPB;
+import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolServerSideTranslatorPB;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -163,8 +165,8 @@ import com.google.protobuf.BlockingService;
  * the requests to the active
  * {@link org.apache.hadoop.hdfs.server.namenode.NameNode NameNode}.
  */
-public class RouterRpcServer extends AbstractService
+public class RouterRpcServer extends AbstractService implements ClientProtocol,
-    implements ClientProtocol, NamenodeProtocol, RefreshUserMappingsProtocol {
+    NamenodeProtocol, RefreshUserMappingsProtocol, GetUserMappingsProtocol {
 
   private static final Logger LOG =
       LoggerFactory.getLogger(RouterRpcServer.class);
@@ -207,6 +209,8 @@ public class RouterRpcServer extends AbstractService
   private final RouterNamenodeProtocol nnProto;
   /** ClientProtocol calls. */
   private final RouterClientProtocol clientProto;
+  /** Other protocol calls. */
+  private final RouterUserProtocol routerProto;
   /** Router security manager to handle token operations. */
   private RouterSecurityManager securityManager = null;
   /** Super user credentials that a thread may use. */
@@ -269,6 +273,12 @@ public class RouterRpcServer extends AbstractService
         RefreshUserMappingsProtocolProtos.RefreshUserMappingsProtocolService.
         newReflectiveBlockingService(refreshUserMappingXlator);
 
+    GetUserMappingsProtocolServerSideTranslatorPB getUserMappingXlator =
+        new GetUserMappingsProtocolServerSideTranslatorPB(this);
+    BlockingService getUserMappingService =
+        GetUserMappingsProtocolProtos.GetUserMappingsProtocolService.
+        newReflectiveBlockingService(getUserMappingXlator);
+
     InetSocketAddress confRpcAddress = conf.getSocketAddr(
         RBFConfigKeys.DFS_ROUTER_RPC_BIND_HOST_KEY,
         RBFConfigKeys.DFS_ROUTER_RPC_ADDRESS_KEY,
@@ -297,6 +307,8 @@ public class RouterRpcServer extends AbstractService
         conf, NamenodeProtocolPB.class, nnPbService, this.rpcServer);
     DFSUtil.addPBProtocol(conf, RefreshUserMappingsProtocolPB.class,
         refreshUserMappingService, this.rpcServer);
+    DFSUtil.addPBProtocol(conf, GetUserMappingsProtocolPB.class,
+        getUserMappingService, this.rpcServer);
 
     // Set service-level authorization security policy
     this.serviceAuthEnabled = conf.getBoolean(
@@ -346,6 +358,7 @@ public class RouterRpcServer extends AbstractService
     this.quotaCall = new Quota(this.router, this);
     this.nnProto = new RouterNamenodeProtocol(this);
     this.clientProto = new RouterClientProtocol(conf, this);
+    this.routerProto = new RouterUserProtocol(this);
   }
 
   @Override
@@ -1706,13 +1719,16 @@ public class RouterRpcServer extends AbstractService
 
   @Override
   public void refreshUserToGroupsMappings() throws IOException {
-    LOG.info("Refresh user groups mapping in Router.");
+    routerProto.refreshUserToGroupsMappings();
-    Groups.getUserToGroupsMappingService().refresh();
   }
 
   @Override
   public void refreshSuperUserGroupsConfiguration() throws IOException {
-    LOG.info("Refresh superuser groups configuration in Router.");
+    routerProto.refreshSuperUserGroupsConfiguration();
-    ProxyUsers.refreshSuperUserGroupsConfiguration();
+  }
+
+  @Override
+  public String[] getGroupsForUser(String user) throws IOException {
+    return routerProto.getGroupsForUser(user);
   }
 }

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterUserProtocol.java

@@ -0,0 +1,104 @@
+/**
+ * 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.server.federation.router;
+
+import static org.apache.hadoop.hdfs.server.federation.router.RouterRpcServer.merge;
+
+import java.io.IOException;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.hadoop.hdfs.server.federation.resolver.ActiveNamenodeResolver;
+import org.apache.hadoop.hdfs.server.federation.resolver.FederationNamespaceInfo;
+import org.apache.hadoop.hdfs.server.namenode.NameNode.OperationCategory;
+import org.apache.hadoop.security.Groups;
+import org.apache.hadoop.security.RefreshUserMappingsProtocol;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.authorize.ProxyUsers;
+import org.apache.hadoop.tools.GetUserMappingsProtocol;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Module that implements all the RPC calls in
+ * {@link RefreshUserMappingsProtocol} {@link GetUserMappingsProtocol} in the
+ * {@link RouterRpcServer}.
+ */
+public class RouterUserProtocol
+    implements RefreshUserMappingsProtocol, GetUserMappingsProtocol {
+
+  private static final Logger LOG =
+      LoggerFactory.getLogger(RouterUserProtocol.class);
+
+  /** RPC server to receive client calls. */
+  private final RouterRpcServer rpcServer;
+  /** RPC clients to connect to the Namenodes. */
+  private final RouterRpcClient rpcClient;
+
+  private final ActiveNamenodeResolver namenodeResolver;
+
+  public RouterUserProtocol(RouterRpcServer server) {
+    this.rpcServer = server;
+    this.rpcClient = this.rpcServer.getRPCClient();
+    this.namenodeResolver = this.rpcServer.getNamenodeResolver();
+  }
+
+  @Override
+  public void refreshUserToGroupsMappings() throws IOException {
+    LOG.debug("Refresh user groups mapping in Router.");
+    rpcServer.checkOperation(OperationCategory.UNCHECKED);
+    Set<FederationNamespaceInfo> nss = namenodeResolver.getNamespaces();
+    if (nss.isEmpty()) {
+      Groups.getUserToGroupsMappingService().refresh();
+    } else {
+      RemoteMethod method = new RemoteMethod(RefreshUserMappingsProtocol.class,
+          "refreshUserToGroupsMappings");
+      rpcClient.invokeConcurrent(nss, method);
+    }
+  }
+
+  @Override
+  public void refreshSuperUserGroupsConfiguration() throws IOException {
+    LOG.debug("Refresh superuser groups configuration in Router.");
+    rpcServer.checkOperation(OperationCategory.UNCHECKED);
+    Set<FederationNamespaceInfo> nss = namenodeResolver.getNamespaces();
+    if (nss.isEmpty()) {
+      ProxyUsers.refreshSuperUserGroupsConfiguration();
+    } else {
+      RemoteMethod method = new RemoteMethod(RefreshUserMappingsProtocol.class,
+          "refreshSuperUserGroupsConfiguration");
+      rpcClient.invokeConcurrent(nss, method);
+    }
+  }
+
+  @Override
+  public String[] getGroupsForUser(String user) throws IOException {
+    LOG.debug("Getting groups for user {}", user);
+    rpcServer.checkOperation(OperationCategory.UNCHECKED);
+    Set<FederationNamespaceInfo> nss = namenodeResolver.getNamespaces();
+    if (nss.isEmpty()) {
+      return UserGroupInformation.createRemoteUser(user).getGroupNames();
+    } else {
+      RemoteMethod method = new RemoteMethod(GetUserMappingsProtocol.class,
+          "getGroupsForUser", new Class<?>[] {String.class}, user);
+      Map<FederationNamespaceInfo, String[]> results =
+          rpcClient.invokeConcurrent(nss, method, String[].class);
+      return merge(results, String.class);
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterRpc.java

@@ -1631,6 +1631,16 @@ public class TestRouterRpc {
     assertFalse(routerDFS.listCacheDirectives(filter).hasNext());
   }
 
+  @Test
+  public void testgetGroupsForUser() throws IOException {
+    String[] group = new String[] {"bar", "group2"};
+    UserGroupInformation.createUserForTesting("user",
+        new String[] {"bar", "group2"});
+    String[] result =
+        router.getRouter().getRpcServer().getGroupsForUser("user");
+    assertArrayEquals(group, result);
+  }
+
   /**
    * Check the erasure coding policies in the Router and the Namenode.
    * @return The erasure coding policies.

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterUserMappings.java

@@ -20,14 +20,16 @@ package org.apache.hadoop.hdfs.server.federation.router;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.NameNodeProxies;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster;
 import org.apache.hadoop.hdfs.server.federation.RouterConfigBuilder;
 import org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider;
 import org.apache.hadoop.hdfs.tools.DFSAdmin;
-import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.hdfs.tools.GetGroups;
 import org.apache.hadoop.security.GroupMappingServiceProvider;
 import org.apache.hadoop.security.Groups;
 import org.apache.hadoop.security.UserGroupInformation;
@@ -36,16 +38,19 @@ import org.apache.hadoop.security.authorize.DefaultImpersonationProvider;
 import org.apache.hadoop.security.authorize.ProxyUsers;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.test.LambdaTestUtils;
+import org.apache.hadoop.tools.GetUserMappingsProtocol;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
 import java.net.URL;
@@ -54,18 +59,20 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 /**
- * Tests RefreshUserMappingsProtocol With Routers.
+ * Test RefreshUserMappingsProtocol and GetUserMappingsProtocol with Routers.
  */
-public class TestRefreshUserMappingsWithRouters {
+public class TestRouterUserMappings {
   private static final Logger LOG = LoggerFactory.getLogger(
-      TestRefreshUserMappingsWithRouters.class);
+      TestRouterUserMappings.class);
 
   private MiniRouterDFSCluster cluster;
   private Router router;
@@ -74,7 +81,6 @@ public class TestRefreshUserMappingsWithRouters {
   private static final String ROUTER_NS = "rbfns";
   private static final String HDFS_SCHEMA = "hdfs://";
   private static final String LOOPBACK_ADDRESS = "127.0.0.1";
-  private static final String HDFS_PREFIX = HDFS_SCHEMA + LOOPBACK_ADDRESS;
 
   private String tempResource = null;
 
@@ -111,7 +117,7 @@ public class TestRefreshUserMappingsWithRouters {
   public void setUp() {
     conf = new Configuration(false);
     conf.setClass("hadoop.security.group.mapping",
-        TestRefreshUserMappingsWithRouters.MockUnixGroupsMapping.class,
+        TestRouterUserMappings.MockUnixGroupsMapping.class,
         GroupMappingServiceProvider.class);
     conf.setLong("hadoop.security.groups.cache.secs",
         GROUP_REFRESH_TIMEOUT_SEC);
@@ -122,23 +128,6 @@ public class TestRefreshUserMappingsWithRouters {
     Groups.getUserToGroupsMappingService(conf);
   }
 
-  /**
-   * Setup a single router, and return this router's rpc address
-   * as fs.defaultFS for {@link DFSAdmin}.
-   * @return router's rpc address
-   * @throws Exception
-   */
-  private String setUpSingleRouterAndReturnDefaultFs() {
-    router = new Router();
-    conf.set(RBFConfigKeys.DFS_ROUTER_RPC_ADDRESS_KEY,
-        LOOPBACK_ADDRESS + ":" + NetUtils.getFreeSocketPort());
-    router.init(conf);
-    router.start();
-    String defaultFs = HDFS_PREFIX + ":" +
-        router.getRpcServerAddress().getPort();
-    return defaultFs;
-  }
-
   /**
    * Setup a multi-routers mini dfs cluster with two nameservices
    * and four routers.
@@ -178,28 +167,14 @@ public class TestRefreshUserMappingsWithRouters {
   }
 
   @Test
-  public void testRefreshSuperUserGroupsConfigurationWithSingleRouter()
+  public void testRefreshSuperUserGroupsConfiguration()
-      throws Exception {
-    testRefreshSuperUserGroupsConfigurationInternal(
-        setUpSingleRouterAndReturnDefaultFs());
-  }
-
-  @Test
-  public void testRefreshSuperUserGroupsConfigurationWithMultiRouters()
       throws Exception {
     testRefreshSuperUserGroupsConfigurationInternal(
         setUpMultiRoutersAndReturnDefaultFs());
   }
 
   @Test
-  public void testGroupMappingRefreshWithSingleRouter() throws Exception {
+  public void testGroupMappingRefresh() throws Exception {
-    testGroupMappingRefreshInternal(
-        setUpSingleRouterAndReturnDefaultFs());
-  }
-
-
-  @Test
-  public void testGroupMappingRefreshWithMultiRouters() throws Exception {
     testGroupMappingRefreshInternal(
         setUpMultiRoutersAndReturnDefaultFs());
   }
@@ -282,6 +257,43 @@ public class TestRefreshUserMappingsWithRouters {
       fail("second auth for " + ugi1.getShortUserName() +
           " should've succeeded: " + e.getLocalizedMessage());
     }
+
+    // get groups
+    testGroupsForUserCLI(conf, "user");
+    testGroupsForUserProtocol(conf, "user");
+  }
+
+  /**
+   * Use the command line to get the groups.
+   * @param config Configuration containing the default filesystem.
+   * @param username Username to check.
+   * @throws Exception If it cannot get the groups.
+   */
+  private void testGroupsForUserCLI(Configuration config, String username)
+      throws Exception {
+    ByteArrayOutputStream out = new ByteArrayOutputStream();
+    PrintStream oldOut = System.out;
+    System.setOut(new PrintStream(out));
+    new GetGroups(config).run(new String[]{username});
+    assertTrue("Wrong output: " + out,
+        out.toString().startsWith(username + " : " + username));
+    out.reset();
+    System.setOut(oldOut);
+  }
+
+  /**
+   * Use the GetUserMappingsProtocol protocol to get the groups.
+   * @param config Configuration containing the default filesystem.
+   * @param username Username to check.
+   * @throws IOException If it cannot get the groups.
+   */
+  private void testGroupsForUserProtocol(Configuration config, String username)
+      throws IOException {
+    GetUserMappingsProtocol proto = NameNodeProxies.createProxy(
+        config, FileSystem.getDefaultUri(config),
+        GetUserMappingsProtocol.class).getProxy();
+    String[] groups = proto.getGroupsForUser(username);
+    assertArrayEquals(new String[] {"user1", "user2"}, groups);
   }
 
   /**