@VisibleForTesting
  public RPC.Server getClientRpcServer() {
    return clientRpcServer;
  }
@Test
  public void testNamenodeRpcBindAny() throws IOException {
    Configuration conf = new HdfsConfiguration();

    // The name node in MiniDFSCluster only binds to 127.0.0.1.
    // We can set the bind address to 0.0.0.0 to make it listen
    // to all interfaces.
    conf.set(DFS_NAMENODE_RPC_BIND_HOST_KEY, "0.0.0.0");
    MiniDFSCluster cluster = null;

    try {
      cluster = new MiniDFSCluster.Builder(conf).build();
      cluster.waitActive();
      assertEquals("0.0.0.0", ((NameNodeRpcServer)cluster.getNameNodeRpc())
          .getClientRpcServer().getListenerAddress().getHostName());
    } finally {
      if (cluster != null) {
        cluster.shutdown();
      }
      // Reset the config
      conf.unset(DFS_NAMENODE_RPC_BIND_HOST_KEY);
    }
  }