001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.yarn.client;
020    
021    import java.io.IOException;
022    import java.net.InetSocketAddress;
023    import java.security.PrivilegedAction;
024    
025    import org.apache.commons.logging.Log;
026    import org.apache.commons.logging.LogFactory;
027    import org.apache.hadoop.classification.InterfaceAudience;
028    import org.apache.hadoop.classification.InterfaceStability;
029    import org.apache.hadoop.conf.Configuration;
030    import org.apache.hadoop.security.UserGroupInformation;
031    import org.apache.hadoop.yarn.ipc.YarnRPC;
032    
033    @InterfaceAudience.Public
034    @InterfaceStability.Evolving
035    @SuppressWarnings("unchecked")
036    public class AHSProxy<T> {
037    
038      private static final Log LOG = LogFactory.getLog(AHSProxy.class);
039    
040      public static <T> T createAHSProxy(final Configuration conf,
041          final Class<T> protocol, InetSocketAddress ahsAddress) throws IOException {
042        LOG.info("Connecting to Application History server at " + ahsAddress);
043        return (T) getProxy(conf, protocol, ahsAddress);
044      }
045    
046      protected static <T> T getProxy(final Configuration conf,
047          final Class<T> protocol, final InetSocketAddress rmAddress)
048          throws IOException {
049        return UserGroupInformation.getCurrentUser().doAs(
050          new PrivilegedAction<T>() {
051            @Override
052            public T run() {
053              return (T) YarnRPC.create(conf).getProxy(protocol, rmAddress, conf);
054            }
055          });
056      }
057    }