Synnefo » snf-ganeti

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"""Chroot manager hypervisor

"""

import os

import os.path

import time

import logging

from ganeti import constants

from ganeti import errors # pylint: disable-msg=W0611

from ganeti import utils

from ganeti.hypervisor import hv_base

from ganeti.errors import HypervisorError

class ChrootManager(hv_base.BaseHypervisor):

  """Chroot manager.

  This not-really hypervisor allows ganeti to manage chroots. It has

  special behaviour and requirements on the OS definition and the node

  environemnt:

    - the start and stop of the chroot environment are done via a

      script called ganeti-chroot located in the root directory of the

      first drive, which should be created by the OS definition

    - this script must accept the start and stop argument and, on

      shutdown, it should cleanly shutdown the daemons/processes

      using the chroot

    - the daemons run in chroot should only bind to the instance IP

      (to which the OS create script has access via the instance name)

    - since some daemons in the node could be listening on the wildcard

      address, some ports might be unavailable

    - the instance listing will show no memory usage

    - on shutdown, the chroot manager will try to find all mountpoints

      under the root dir of the instance and unmount them

    - instance alive check is based on whether any process is using the chroot

  """

  _ROOT_DIR = constants.RUN_GANETI_DIR + "/chroot-hypervisor"

  PARAMETERS = {

    constants.HV_INIT_SCRIPT: (True, utils.IsNormAbsPath,

                               "must be an absolute normalized path",

                               None, None),

    }

  def __init__(self):

    hv_base.BaseHypervisor.__init__(self)

    if not os.path.exists(self._ROOT_DIR):

      os.mkdir(self._ROOT_DIR)

    if not os.path.isdir(self._ROOT_DIR):

      raise HypervisorError("Needed path %s is not a directory" %

                            self._ROOT_DIR)

  @staticmethod

  def _IsDirLive(path):

    """Check if a directory looks like a live chroot.

    """

    if not os.path.ismount(path):

      return False

    result = utils.RunCmd(["fuser", "-m", path])

    return not result.failed

  @staticmethod

  def _GetMountSubdirs(path):

    """Return the list of mountpoints under a given path.

    This function is Linux-specific.

    """

    #TODO(iustin): investigate and document non-linux options

    #(e.g. via mount output)

    data = []

    fh = open("/proc/mounts", "r")

    try:

      for line in fh:

        _, mountpoint, _ = line.split(" ", 2)

        if (mountpoint.startswith(path) and

            mountpoint != path):

          data.append(mountpoint)

    finally:

      fh.close()

    data.sort(key=lambda x: x.count("/"), reverse=True)

    return data

  @classmethod

  def _InstanceDir(cls, instance_name):

    """Return the root directory for an instance.

    """

    return utils.PathJoin(cls._ROOT_DIR, instance_name)

  def ListInstances(self):

    """Get the list of running instances.

    """

    return [name for name in os.listdir(self._ROOT_DIR)

            if self._IsDirLive(utils.PathJoin(self._ROOT_DIR, name))]

  def GetInstanceInfo(self, instance_name):

    """Get instance properties.

    @type instance_name: string

    @param instance_name: the instance name

    @return: (name, id, memory, vcpus, stat, times)

    """

    dir_name = self._InstanceDir(instance_name)

    if not self._IsDirLive(dir_name):

      raise HypervisorError("Instance %s is not running" % instance_name)

    return (instance_name, 0, 0, 0, 0, 0)

  def GetAllInstancesInfo(self):

    """Get properties of all instances.

    @return: [(name, id, memory, vcpus, stat, times),...]

    """

    data = []

    for file_name in os.listdir(self._ROOT_DIR):

      path = utils.PathJoin(self._ROOT_DIR, file_name)

      if self._IsDirLive(path):

        data.append((file_name, 0, 0, 0, 0, 0))

    return data

  def StartInstance(self, instance, block_devices):

    """Start an instance.

    For the chroot manager, we try to mount the block device and

    execute '/ganeti-chroot start'.

    """

    root_dir = self._InstanceDir(instance.name)

    if not os.path.exists(root_dir):

      try:

        os.mkdir(root_dir)

      except IOError, err:

        raise HypervisorError("Failed to start instance %s: %s" %

                              (instance.name, err))

      if not os.path.isdir(root_dir):

        raise HypervisorError("Needed path %s is not a directory" % root_dir)

    if not os.path.ismount(root_dir):

      if not block_devices:

        raise HypervisorError("The chroot manager needs at least one disk")

      sda_dev_path = block_devices[0][1]

      result = utils.RunCmd(["mount", sda_dev_path, root_dir])

      if result.failed:

        raise HypervisorError("Can't mount the chroot dir: %s" % result.output)

    init_script = instance.hvparams[constants.HV_INIT_SCRIPT]

    result = utils.RunCmd(["chroot", root_dir, init_script, "start"])

    if result.failed:

      raise HypervisorError("Can't run the chroot start script: %s" %

                            result.output)

  def StopInstance(self, instance, force=False, retry=False):

    """Stop an instance.

    This method has complicated cleanup tests, as we must:

      - try to kill all leftover processes

      - try to unmount any additional sub-mountpoints

      - finally unmount the instance dir

    """

    root_dir = self._InstanceDir(instance.name)

    if not os.path.exists(root_dir) or not self._IsDirLive(root_dir):

      return

    # Run the chroot stop script only once

    if not retry and not force:

      result = utils.RunCmd(["chroot", root_dir, "/ganeti-chroot", "stop"])

      if result.failed:

        raise HypervisorError("Can't run the chroot stop script: %s" %

                              result.output)

    if not force:

      utils.RunCmd(["fuser", "-k", "-TERM", "-m", root_dir])

    else:

      utils.RunCmd(["fuser", "-k", "-KILL", "-m", root_dir])

      # 2 seconds at most should be enough for KILL to take action

      time.sleep(2)

    if self._IsDirLive(root_dir):

      if force:

        raise HypervisorError("Can't stop the processes using the chroot")

      return

    for mpath in self._GetMountSubdirs(root_dir):

      utils.RunCmd(["umount", mpath])

    result = utils.RunCmd(["umount", root_dir])

    if result.failed and force:

      msg = ("Processes still alive in the chroot: %s" %

             utils.RunCmd("fuser -vm %s" % root_dir).output)

      logging.error(msg)

      raise HypervisorError("Can't umount the chroot dir: %s (%s)" %

                            (result.output, msg))

  def RebootInstance(self, instance):

    """Reboot an instance.

    This is not (yet) implemented for the chroot manager.

    """

    raise HypervisorError("The chroot manager doesn't implement the"

                          " reboot functionality")

  def GetNodeInfo(self):

    """Return information about the node.

    This is just a wrapper over the base GetLinuxNodeInfo method.

    @return: a dict with the following keys (values in MiB):

          - memory_total: the total memory size on the node

          - memory_free: the available memory on the node for instances

          - memory_dom0: the memory used by the node itself, if available

    """

    return self.GetLinuxNodeInfo()

  @classmethod

  def GetShellCommandForConsole(cls, instance, hvparams, beparams):

    """Return a command for connecting to the console of an instance.

    """

    root_dir = cls._InstanceDir(instance.name)

    if not os.path.ismount(root_dir):

      raise HypervisorError("Instance %s is not running" % instance.name)

    return "chroot %s" % root_dir

  def Verify(self):

    """Verify the hypervisor.

    For the chroot manager, it just checks the existence of the base dir.

    """

    if not os.path.exists(self._ROOT_DIR):

      return "The required directory '%s' does not exist." % self._ROOT_DIR

  @classmethod

  def PowercycleNode(cls):

    """Chroot powercycle, just a wrapper over Linux powercycle.

    """

    cls.LinuxPowercycle()

  def MigrateInstance(self, instance, target, live):

    """Migrate an instance.

    @type instance: L{object.Instance}

    @param instance: the instance to be migrated

    @type target: string

    @param target: hostname (usually ip) of the target node

    @type live: boolean

    @param live: whether to do a live or non-live migration

    """

    raise HypervisorError("Migration not supported by the chroot hypervisor")