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#
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#
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# Copyright (C) 2006, 2007 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Global Configuration data for Ganeti.
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This module provides the interface to a special case of cluster
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configuration data, which is mostly static and available to all nodes.
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"""
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import os
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import tempfile
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import errno
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import socket
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from ganeti import errors
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from ganeti import constants
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class SimpleStore:
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  """Interface to static cluster data.
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  This is different that the config.ConfigWriter class in that it
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  holds data that is (mostly) constant after the cluster
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  initialization. Its purpose is to allow limited customization of
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  things which would otherwise normally live in constants.py. Note
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  that this data cannot live in ConfigWriter as that is available only
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  on the master node, and our data must be readable by both the master
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  and the nodes.
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  Other particularities of the datastore:
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    - keys are restricted to predefined values
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    - values are small (<4k)
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    - since the data is practically static, read keys are cached in memory
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    - some keys are handled specially (read from the system, so
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      we can't update them)
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  """
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  _SS_FILEPREFIX = "ssconf_"
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  SS_HYPERVISOR = "hypervisor"
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  SS_NODED_PASS = "node_pass"
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  SS_MASTER_NODE = "master_node"
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  SS_MASTER_IP = "master_ip"
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  SS_MASTER_NETDEV = "master_netdev"
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  SS_CLUSTER_NAME = "cluster_name"
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  _VALID_KEYS = (SS_HYPERVISOR, SS_NODED_PASS, SS_MASTER_NODE, SS_MASTER_IP,
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                 SS_MASTER_NETDEV, SS_CLUSTER_NAME)
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  _MAX_SIZE = 4096
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  def __init__(self, cfg_location=None):
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    if cfg_location is None:
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      self._cfg_dir = constants.DATA_DIR
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    else:
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      self._cfg_dir = cfg_location
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    self._cache = {}
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  def KeyToFilename(self, key):
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    """Convert a given key into filename.
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    """
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    if key not in self._VALID_KEYS:
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      raise errors.ProgrammerError("Invalid key requested from SSConf: '%s'"
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                                   % str(key))
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    filename = self._cfg_dir + '/' + self._SS_FILEPREFIX + key
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    return filename
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  def _ReadFile(self, key):
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    """Generic routine to read keys.
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    This will read the file which holds the value requested. Errors
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    will be changed into ConfigurationErrors.
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    """
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    if key in self._cache:
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      return self._cache[key]
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    filename = self.KeyToFilename(key)
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    try:
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      fh = file(filename, 'r')
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      try:
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        data = fh.readline(self._MAX_SIZE)
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        data = data.rstrip('\n')
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      finally:
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        fh.close()
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    except EnvironmentError, err:
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      raise errors.ConfigurationError("Can't read from the ssconf file:"
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                                      " '%s'" % str(err))
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    self._cache[key] = data
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    return data
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  def GetNodeDaemonPort(self):
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    """Get the node daemon port for this cluster.
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    Note that this routine does not read a ganeti-specific file, but
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    instead uses socket.getservbyname to allow pre-customization of
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    this parameter outside of ganeti.
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    """
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    try:
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      port = socket.getservbyname("ganeti-noded", "tcp")
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    except socket.error:
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      port = constants.DEFAULT_NODED_PORT
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    return port
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  def GetHypervisorType(self):
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    """Get the hypervisor type for this cluster.
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    """
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    return self._ReadFile(self.SS_HYPERVISOR)
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  def GetNodeDaemonPassword(self):
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    """Get the node password for this cluster.
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    """
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    return self._ReadFile(self.SS_NODED_PASS)
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  def GetMasterNode(self):
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    """Get the hostname of the master node for this cluster.
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    """
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    return self._ReadFile(self.SS_MASTER_NODE)
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  def GetMasterIP(self):
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    """Get the IP of the master node for this cluster.
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    """
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    return self._ReadFile(self.SS_MASTER_IP)
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  def GetMasterNetdev(self):
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    """Get the netdev to which we'll add the master ip.
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    """
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    return self._ReadFile(self.SS_MASTER_NETDEV)
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  def GetClusterName(self):
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    """Get the cluster name.
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    """
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    return self._ReadFile(self.SS_CLUSTER_NAME)
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  def SetKey(self, key, value):
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    """Set the value of a key.
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    This should be used only when adding a node to a cluster.
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    """
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    file_name = self.KeyToFilename(key)
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    dir_name, small_name = os.path.split(file_name)
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    fd, new_name = tempfile.mkstemp('.new', small_name, dir_name)
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    # here we need to make sure we remove the temp file, if any error
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    # leaves it in place
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    try:
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      os.chown(new_name, 0, 0)
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      os.chmod(new_name, 0400)
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      os.write(fd, "%s\n" % str(value))
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      os.fsync(fd)
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      os.rename(new_name, file_name)
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      self._cache[key] = value
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    finally:
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      os.close(fd)
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      try:
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        os.unlink(new_name)
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      except OSError, err:
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        if err.errno != errno.ENOENT:
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          raise
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  def GetFileList(self):
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    """Return the lis of all config files.
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    This is used for computing node replication data.
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    """
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    return [self.KeyToFilename(key) for key in self._VALID_KEYS]