Synnefo » snf-ganeti

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# Copyright (C) 2006, 2007, 2008 Google Inc.

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# General Public License for more details.

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"""Fake hypervisor

"""

import os

import os.path

import logging

from ganeti import utils

from ganeti import constants

from ganeti import errors

from ganeti.hypervisor import hv_base

class FakeHypervisor(hv_base.BaseHypervisor):

  """Fake hypervisor interface.

  This can be used for testing the ganeti code without having to have

  a real virtualisation software installed.

  """

  _ROOT_DIR = constants.RUN_DIR + "/ganeti-fake-hypervisor"

  def __init__(self):

    hv_base.BaseHypervisor.__init__(self)

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

      os.mkdir(self._ROOT_DIR)

  def ListInstances(self):

    """Get the list of running instances.

    """

    return os.listdir(self._ROOT_DIR)

  def GetInstanceInfo(self, instance_name):

    """Get instance properties.

    @param instance_name: the instance name

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

    """

    file_name = "%s/%s" % (self._ROOT_DIR, instance_name)

    if not os.path.exists(file_name):

      return None

    try:

      fh = open(file_name, "r")

      try:

        inst_id = fh.readline().strip()

        memory = utils.TryConvert(int, fh.readline().strip())

        vcpus = utils.TryConvert(int, fh.readline().strip())

        stat = "---b-"

        times = "0"

        return (instance_name, inst_id, memory, vcpus, stat, times)

      finally:

        fh.close()

    except IOError, err:

      raise errors.HypervisorError("Failed to list instance %s: %s" %

                                   (instance_name, err))

  def GetAllInstancesInfo(self):

    """Get properties of all instances.

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

    """

    data = []

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

      try:

        fh = open(self._ROOT_DIR + "/" + file_name, "r")

        inst_id = "-1"

        memory = 0

        vcpus = 1

        stat = "-----"

        times = "-1"

        try:

          inst_id = fh.readline().strip()

          memory = utils.TryConvert(int, fh.readline().strip())

          vcpus = utils.TryConvert(int, fh.readline().strip())

          stat = "---b-"

          times = "0"

        finally:

          fh.close()

        data.append((file_name, inst_id, memory, vcpus, stat, times))

      except IOError, err:

        raise errors.HypervisorError("Failed to list instances: %s" % err)

    return data

  def _InstanceFile(self, instance_name):

    """Compute the instance file for an instance name.

    """

    return self._ROOT_DIR + "/%s" % instance_name

  def _IsAlive(self, instance_name):

    """Checks if an instance is alive.

    """

    file_name = self._InstanceFile(instance_name)

    return os.path.exists(file_name)

  def _MarkUp(self, instance):

    """Mark the instance as running.

    This does no checks, which should be done by its callers.

    """

    file_name = self._InstanceFile(instance.name)

    fh = file(file_name, "w")

    try:

      fh.write("0\n%d\n%d\n" %

               (instance.beparams[constants.BE_MEMORY],

                instance.beparams[constants.BE_VCPUS]))

    finally:

      fh.close()

  def _MarkDown(self, instance):

    """Mark the instance as running.

    This does no checks, which should be done by its callers.

    """

    file_name = self._InstanceFile(instance.name)

    utils.RemoveFile(file_name)

  def StartInstance(self, instance, block_devices):

    """Start an instance.

    For the fake hypervisor, it just creates a file in the base dir,

    creating an exception if it already exists. We don't actually

    handle race conditions properly, since these are *FAKE* instances.

    """

    if self._IsAlive(instance.name):

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

                                   (instance.name, "already running"))

    try:

      self._MarkUp(instance)

    except IOError, err:

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

                                   (instance.name, err))

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

    """Stop an instance.

    For the fake hypervisor, this just removes the file in the base

    dir, if it exist, otherwise we raise an exception.

    """

    if not self._IsAlive(instance.name):

      raise errors.HypervisorError("Failed to stop instance %s: %s" %

                                   (instance.name, "not running"))

    self._MarkDown(instance)

  def RebootInstance(self, instance):

    """Reboot an instance.

    For the fake hypervisor, this does nothing.

    """

    return

  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

    """

    result = self.GetLinuxNodeInfo()

    # substract running instances

    all_instances = self.GetAllInstancesInfo()

    result['memory_free'] -= min(result['memory_free'],

                                 sum([row[2] for row in all_instances]))

    return result

  @classmethod

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

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

    """

    return "echo Console not available for fake hypervisor"

  def Verify(self):

    """Verify the hypervisor.

    For the fake hypervisor, 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):

    """Fake hypervisor powercycle, just a wrapper over Linux powercycle.

    """

    cls.LinuxPowercycle()

  def AcceptInstance(self, instance, info, target):

    """Prepare to accept an instance.

    @type instance: L{objects.Instance}

    @param instance: instance to be accepted

    @type info: string

    @param info: instance info, not used

    @type target: string

    @param target: target host (usually ip), on this node

    """

    if self._IsAlive(instance.name):

      raise errors.HypervisorError("Can't accept instance, already running")

  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

    """

    logging.debug("Fake hypervisor migrating %s to %s (live=%s)",

                  instance, target, live)

    self._MarkDown(instance)

  def FinalizeMigration(self, instance, info, success):

    """Finalize an instance migration.

    For the fake hv, this just marks the instance up.

    @type instance: L{objects.Instance}

    @param instance: instance whose migration is being finalized

    """

    if success:

      self._MarkUp(instance)

    else:

      # ensure it's down

      self._MarkDown(instance)