Synnefo » snf-ganeti

class SimpleStore:

  """Interface to static cluster data.

  This is different that the config.ConfigWriter class in that it

  holds data that is (mostly) constant after the cluster

  initialization. Its purpose is to allow limited customization of

  things which would otherwise normally live in constants.py. Note

  that this data cannot live in ConfigWriter as that is available only

  on the master node, and our data must be readable by both the master

  and the nodes.

  Other particularities of the datastore:

    - keys are restricted to predefined values

    - values are small (<4k)

    - some keys are handled specially (read from the system)

  """

  _SS_FILEPREFIX = "ssconf_"

  SS_HYPERVISOR = "hypervisor"

  SS_NODED_PASS = "node_pass"

  SS_MASTER_NODE = "master_node"

  SS_MASTER_IP = "master_ip"

  SS_MASTER_NETDEV = "master_netdev"

  SS_CLUSTER_NAME = "cluster_name"

  SS_FILE_STORAGE_DIR = "file_storage_dir"

  SS_CONFIG_VERSION = "config_version"

  _VALID_KEYS = (SS_HYPERVISOR, SS_NODED_PASS, SS_MASTER_NODE, SS_MASTER_IP,

                 SS_MASTER_NETDEV, SS_CLUSTER_NAME, SS_FILE_STORAGE_DIR,

                 SS_CONFIG_VERSION)

  _MAX_SIZE = 4096

  def __init__(self, cfg_location=None):

    if cfg_location is None:

      self._cfg_dir = constants.DATA_DIR

    else:

      self._cfg_dir = cfg_location

  def KeyToFilename(self, key):

    """Convert a given key into filename.

    """

    if key not in self._VALID_KEYS:

      raise errors.ProgrammerError("Invalid key requested from SSConf: '%s'"

                                   % str(key))

    filename = self._cfg_dir + '/' + self._SS_FILEPREFIX + key

    return filename

  def _ReadFile(self, key):

    """Generic routine to read keys.

    This will read the file which holds the value requested. Errors

    will be changed into ConfigurationErrors.

    """

    filename = self.KeyToFilename(key)

    try:

      fh = file(filename, 'r')

      try:

        data = fh.readline(self._MAX_SIZE)

        data = data.rstrip('\n')

      finally:

        fh.close()

    except EnvironmentError, err:

      raise errors.ConfigurationError("Can't read from the ssconf file:"

                                      " '%s'" % str(err))

    return data

  def GetNodeDaemonPort(self):

    """Get the node daemon port for this cluster.

    Note that this routine does not read a ganeti-specific file, but

    instead uses socket.getservbyname to allow pre-customization of

    this parameter outside of ganeti.

    """

    try:

      port = socket.getservbyname("ganeti-noded", "tcp")

    except socket.error:

      port = constants.DEFAULT_NODED_PORT

    return port

  def GetHypervisorType(self):

    """Get the hypervisor type for this cluster.

    """

    return self._ReadFile(self.SS_HYPERVISOR)

  def GetNodeDaemonPassword(self):

    """Get the node password for this cluster.

    """

    return self._ReadFile(self.SS_NODED_PASS)

  def GetMasterNode(self):

    """Get the hostname of the master node for this cluster.

    """

    return self._ReadFile(self.SS_MASTER_NODE)

  def GetMasterIP(self):

    """Get the IP of the master node for this cluster.

    """

    return self._ReadFile(self.SS_MASTER_IP)

  def GetMasterNetdev(self):

    """Get the netdev to which we'll add the master ip.

    """

    return self._ReadFile(self.SS_MASTER_NETDEV)

  def GetClusterName(self):

    """Get the cluster name.

    """

    return self._ReadFile(self.SS_CLUSTER_NAME)

  def GetFileStorageDir(self):

    """Get the file storage dir.

    """

    return self._ReadFile(self.SS_FILE_STORAGE_DIR)

  def GetConfigVersion(self):

    """Get the configuration version.

    """

    value = self._ReadFile(self.SS_CONFIG_VERSION)

    try:

      return int(value)

    except (ValueError, TypeError), err:

      raise errors.ConfigurationError("Failed to convert config version %s to"

                                      " int: '%s'" % (value, str(err)))

  def GetFileList(self):

    """Return the list of all config files.

    This is used for computing node replication data.

    """

    return [self.KeyToFilename(key) for key in self._VALID_KEYS]

class WritableSimpleStore(SimpleStore):

  """This is a read/write interface to SimpleStore, which is used rarely, when

  values need to be changed. Since WriteFile handles updates in an atomic way

  it should be fine to use two WritableSimpleStore at the same time, but in

  the future we might want to put additional protection for this class.

  A WritableSimpleStore cannot be used to update system-dependent values.

  """

  def SetKey(self, key, value):

    """Set the value of a key.

    This should be used only when adding a node to a cluster, or in other

    infrequent operations such as cluster-rename or master-failover.

    """

    file_name = self.KeyToFilename(key)

    utils.WriteFile(file_name, data="%s\n" % str(value),

                    uid=0, gid=0, mode=0400)