is_master/bin/is_slave

#!/usr/bin/env ruby
# 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.

require 'socket'

if ARGV.length < 2
  puts 'is_slave execute a command when it determine that server is slave'
  puts "Usage: #{$PROGRAM_NAME} [VIP|FILE] COMMAND"
  puts '  VIP     - IP address expected to be master'
  puts '  FILE    - File expected to be master'
  puts '  COMMAND - Command to execute if host is slave'
  exit 2
end

expected = ARGV[0]
command  = ARGV[1..-1].join(' ')

if !Socket.ip_address_list.map(&:ip_address).include?(expected) && !File.exist?(expected)
  Kernel.exec(command)
else
  puts 'OK - I am master, i going to sleep'
end