Synnefo » snf-ganeti

#

# Copyright (C) 2010 Google Inc.

#

# 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.

"""Module implementing configuration details at runtime.

"""

import grp

import pwd

import threading

from ganeti import constants

from ganeti import errors

_priv = None

_priv_lock = threading.Lock()

def GetUid(user, _getpwnam):

  """Retrieve the uid from the database.

  @type user: string

  @param user: The username to retrieve

  @return: The resolved uid

  """

  try:

    return _getpwnam(user).pw_uid

  except KeyError, err:

    raise errors.ConfigurationError("User '%s' not found (%s)" % (user, err))

def GetGid(group, _getgrnam):

  """Retrieve the gid from the database.

  @type group: string

  @param group: The group name to retrieve

  @return: The resolved gid

  """

  try:

    return _getgrnam(group).gr_gid

  except KeyError, err:

    raise errors.ConfigurationError("Group '%s' not found (%s)" % (group, err))

class GetentResolver:

  """Resolves Ganeti uids and gids by name.

  @ivar masterd_uid: The resolved uid of the masterd user

  @ivar masterd_gid: The resolved gid of the masterd group

  @ivar confd_uid: The resolved uid of the confd user

  @ivar confd_gid: The resolved gid of the confd group

  @ivar rapi_uid: The resolved uid of the rapi user

  @ivar rapi_gid: The resolved gid of the rapi group

  @ivar noded_uid: The resolved uid of the noded user

  @ivar daemons_gid: The resolved gid of the daemons group

  @ivar admin_gid: The resolved gid of the admin group

  """

  def __init__(self, _getpwnam=pwd.getpwnam, _getgrnam=grp.getgrnam):

    """Initialize the resolver.

    """

    # Daemon pairs

    self.masterd_uid = GetUid(constants.MASTERD_USER, _getpwnam)

    self.masterd_gid = GetGid(constants.MASTERD_GROUP, _getgrnam)

    self.confd_uid = GetUid(constants.CONFD_USER, _getpwnam)

    self.confd_gid = GetGid(constants.CONFD_GROUP, _getgrnam)

    self.rapi_uid = GetUid(constants.RAPI_USER, _getpwnam)

    self.rapi_gid = GetGid(constants.RAPI_GROUP, _getgrnam)

    self.noded_uid = GetUid(constants.NODED_USER, _getpwnam)

    # Misc Ganeti groups

    self.daemons_gid = GetGid(constants.DAEMONS_GROUP, _getgrnam)

    self.admin_gid = GetGid(constants.ADMIN_GROUP, _getgrnam)

def GetEnts(resolver=GetentResolver):

  """Singleton wrapper around resolver instance.

  As this method is accessed by multiple threads at the same time

  we need to take thread-safty carefully

  """

  # We need to use the global keyword here

  global _priv # pylint: disable-msg=W0603

  if not _priv:

    _priv_lock.acquire()

    try:

      if not _priv:

        # W0621: Redefine '_priv' from outer scope (used for singleton)

        _priv = resolver() # pylint: disable-msg=W0621

    finally:

      _priv_lock.release()

  return _priv