new_contents: # The MIT License (MIT)
  #
  # Copyright (c) 2015 Taio Jia (jiasir) <jiasir@icloud.com>
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in all
  # copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  
  __author__ = 'jiasir'
  
  usage = """
  add_swap.py [ubuntu@controller01] [ubuntu@controller02] [...]
  """
  
  swap_space = '24G'
  
  from fabric.api import *
  from fabric.contrib import files
  import sys
  
  
  def add_swap(space):
      sudo('fallocate -l {space} /mnt/{space}.swap'.format(space=space))
      sudo('mkswap /mnt/{space}.swap'.format(space=space))
      sudo('swapon /mnt/{space}.swap'.format(space=space))
      files.append('/etc/fstab', '/mnt/{space}.swap  none  swap  sw 0  0'.format(space=space), use_sudo=True)
      sudo('swapon -s')
      sudo('chmod 600 /mnt/{space}.swap'.format(space=space))
  
  
  def main():
      env.hosts = sys.argv[1:]
      for host in env.hosts:
          env.host_string = host
          add_swap(swap_space)
  
  
  if __name__ == '__main__':
      main()
  
subject: Add compute swap when needed