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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  
20  package org.apache.hadoop.hbase.zookeeper;
21  
22  import java.util.LinkedList;
23  import java.util.List;
24  import java.util.Properties;
25  import java.util.Map.Entry;
26  
27  import org.apache.hadoop.hbase.HConstants;
28  import org.apache.hadoop.hbase.ServerName;
29  import org.apache.hadoop.hbase.classification.InterfaceAudience;
30  import org.apache.hadoop.hbase.classification.InterfaceStability;
31  import org.apache.hadoop.conf.Configuration;
32  import org.apache.hadoop.hbase.HBaseConfiguration;
33  
34  /**
35   * Tool for reading ZooKeeper servers from HBase XML configuration and producing
36   * a line-by-line list for use by bash scripts.
37   */
38  @InterfaceAudience.Public
39  @InterfaceStability.Evolving
40  public class ZKServerTool {
41  
42    public static ServerName[] readZKNodes(Configuration conf) {
43      List<ServerName> hosts = new LinkedList<ServerName>();
44  
45      // Note that we do not simply grab the property
46      // HConstants.ZOOKEEPER_QUORUM from the HBaseConfiguration because the
47      // user may be using a zoo.cfg file.
48      Properties zkProps = ZKConfig.makeZKProps(conf);
49      for (Entry<Object, Object> entry : zkProps.entrySet()) {
50        String key = entry.getKey().toString().trim();
51        String value = entry.getValue().toString().trim();
52        if (key.startsWith("server.")) {
53          String[] parts = value.split(":");
54          String host = parts[0];
55  
56          int port = HConstants.DEFAULT_ZOOKEPER_CLIENT_PORT;
57          if (parts.length > 1) {
58            port = Integer.parseInt(parts[1]);
59          }
60          hosts.add(ServerName.valueOf(host, port, -1));
61        }
62      }
63      return hosts.toArray(new ServerName[hosts.size()]);
64    }
65  
66    /**
67     * Run the tool.
68     * @param args Command line arguments.
69     */
70    public static void main(String args[]) {
71      for(ServerName server: readZKNodes(HBaseConfiguration.create())) {
72        // bin/zookeeper.sh relies on the "ZK host" string for grepping which is case sensitive.
73        System.out.println("ZK host: " + server.getHostname());
74      }
75    }
76  }