Synnefo » snf-ganeti » Ganeti ExtStorage providers

#!/usr/bin/env python

#

# Copyright (C) 2011 Greek Research and Technology Network

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""Map an existing rbd Image to a block device

This program maps an existing rbd Image to a block device

e.g. /dev/rbd{X} and returns the device path. If the mapping

already exists, it returns the corresponding device path.

It takes it's input from environment variables. Specifically the

following variables should be present:

 - VOL_NAME: The name of the Image to map

 - POOL:     The RADOS pool in which the Image resides

Returns the block device path (which maps the Image) as a string

upon success, or 1 upon failure

"""

import os

import sys

import re

sys.path.insert(0, "/etc/ganeti/share")

from ganeti import utils

def ReadEnv():

  """Read the mandatory enviromental variables

  """

  name = os.getenv("VOL_NAME")

  if name is None:

    sys.stderr.write('The environment variable VOL_NAME is missing.\n')

    return None

#  pool = os.getenv("POOL")

  pool = "rbd"

  if pool is None:

    sys.stderr.write('The environment variable POOL is missing.\n')

    return None

  return (name, pool)

def main():

  env = ReadEnv()

  if env is None:

    sys.stderr.write('Wrong environment. Aborting...\n')

    return 1

  name, pool = env

  # Check if the mapping already exists

  cmd1 = ["rbd", "showmapped"]

  result = utils.RunCmd(cmd1)

  if result.failed:

    sys.stderr.write("rbd showmapped failed (%s): %s" %

                     (result.fail_reason, result.output))

    return 1

  else:

    cmd2 = "echo '%s' | grep %s | grep %s" % (result.output, pool, name)

    result = utils.RunCmd(cmd2)

    if not result.failed:

      # The mapping already exists.

      # Parse the result and return the rbd device

      try:

        rbd_dev = re.search("(/dev/rbd\d+)", result.output).group(1)

      except:

        sys.stderr.write("The rbd mapping exists but couldn't parse "

                         "the result of rbd showmapped to find the "

                         "corresponding rbd block device (/dev/rbd*)")

        return 1

      #return str(rbd_dev)

      sys.stdout.write("%s" % str(rbd_dev))

      sys.exit(0)

    else:

      # The mapping doesn't exist. Create it

      cmd = ["rbd", "map", "-p", "%s" % pool, "%s" % name]

      result = utils.RunCmd(cmd)

      if result.failed:

        sys.stderr.write("rbd map failed (%s): %s" % 

                         (result.fail_reason, result.output))

        return 1

      # Use rbd showmapped again to find the rbd device

      # the image was mapped to

      cmd3 = "rbd showmapped | grep %s | grep %s" % (pool, name)

      result = utils.RunCmd(cmd3)

      if result.failed:

        sys.stderr.write("Can't find mapped device. "

                         "rbd showmapped failed (%s): %s" %

                         (result.fail_reason, result.output))

        return 1

      try:

        rbd_dev = re.search("(/dev/rbd\d+)", result.output).group(1)

      except:

        sys.stderr.write("The rbd mapping was created succesfully, but "

                         "couldn't parse the result of rbd showmapped to "

                         "find the corresponding rbd block device "

                         "(/dev/rbd*)")

        return 1

      # The device was successfully mapped. Return it

      #return str(rbd_dev)

      sys.stdout.write("%s" % str(rbd_dev))

      sys.exit(0)

if __name__ == "__main__":

    sys.exit(main())