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

import platform

from ganeti import constants

from ganeti import errors

from ganeti import utils

_priv = None

_priv_lock = threading.Lock()

#: Architecture information

_arch = None

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)

    self.noded_gid = GetGid(constants.NODED_GROUP, _getgrnam)

    # Misc Ganeti groups

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

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

    self._uid2user = {

      self.masterd_uid: constants.MASTERD_USER,

      self.confd_uid: constants.CONFD_USER,

      self.rapi_uid: constants.RAPI_USER,

      self.noded_uid: constants.NODED_USER,

      }

    self._gid2group = {

      self.masterd_gid: constants.MASTERD_GROUP,

      self.confd_gid: constants.CONFD_GROUP,

      self.rapi_gid: constants.RAPI_GROUP,

      self.noded_gid: constants.NODED_GROUP,

      self.daemons_gid: constants.DAEMONS_GROUP,

      self.admin_gid: constants.ADMIN_GROUP,

      }

    self._user2uid = utils.InvertDict(self._uid2user)

    self._group2gid = utils.InvertDict(self._gid2group)

  def LookupUid(self, uid):

    """Looks which Ganeti user belongs to this uid.

    @param uid: The uid to lookup

    @returns The user name associated with that uid

    """

    try:

      return self._uid2user[uid]

    except KeyError:

      raise errors.ConfigurationError("Unknown Ganeti uid '%d'" % uid)

  def LookupGid(self, gid):

    """Looks which Ganeti group belongs to this gid.

    @param gid: The gid to lookup

    @returns The group name associated with that gid

    """

    try:

      return self._gid2group[gid]

    except KeyError:

      raise errors.ConfigurationError("Unknown Ganeti gid '%d'" % gid)

  def LookupUser(self, name):

    """Looks which uid belongs to this name.

    @param name: The name to lookup

    @returns The uid associated with that user name

    """

    try:

      return self._user2uid[name]

    except KeyError:

      raise errors.ConfigurationError("Unknown Ganeti user '%s'" % name)

  def LookupGroup(self, name):

    """Looks which gid belongs to this name.

    @param name: The name to lookup

    @returns The gid associated with that group name

    """

    try:

      return self._group2gid[name]

    except KeyError:

      raise errors.ConfigurationError("Unknown Ganeti group '%s'" % name)

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-safety carefully.

  """

  # We need to use the global keyword here

  global _priv # pylint: disable=W0603

  if not _priv:

    _priv_lock.acquire()

    try:

      if not _priv:

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

        _priv = resolver() # pylint: disable=W0621

    finally:

      _priv_lock.release()

  return _priv

def InitArchInfo():

  """Initialize architecture information.

  We can assume this information never changes during the lifetime of a

  process, therefore the information can easily be cached.

  @note: This function uses C{platform.architecture} to retrieve the Python

    binary architecture and does so by forking to run C{file} (see Python

    documentation for more information). Therefore it must not be used in a

    multi-threaded environment.

  """

  global _arch # pylint: disable=W0603

  if _arch is not None:

    raise errors.ProgrammerError("Architecture information can only be"

                                 " initialized once")

  _arch = (platform.architecture()[0], platform.machine())

def GetArchInfo():

  """Returns previsouly initialized architecture information.

  """

  if _arch is None:

    raise errors.ProgrammerError("Architecture information hasn't been"

                                 " initialized")

  return _arch