get-active-master.rb

#!/usr/bin/env hbase-jruby
#
# 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
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# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
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# Prints the hostname of the machine running the active master.

include Java
java_import org.apache.hadoop.hbase.HBaseConfiguration
java_import org.apache.hadoop.hbase.ServerName
java_import org.apache.hadoop.hbase.zookeeper.ZKWatcher
java_import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker

# disable debug/info logging on this script for clarity
log_level = org.apache.log4j.Level::ERROR
org.apache.log4j.Logger.getLogger('org.apache.hadoop.hbase').setLevel(log_level)
org.apache.log4j.Logger.getLogger('org.apache.zookeeper').setLevel(log_level)

config = HBaseConfiguration.create

zk = ZKWatcher.new(config, 'get-active-master', nil)
begin
  puts MasterAddressTracker.getMasterAddress(zk).getHostname
ensure
  zk.close
end