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"""Xen hypervisors

"""

import logging

import errno

import string # pylint: disable=W0402

import shutil

from cStringIO import StringIO

from ganeti import constants

from ganeti import errors

from ganeti import utils

from ganeti.hypervisor import hv_base

from ganeti import netutils

from ganeti import objects

from ganeti import pathutils

XEND_CONFIG_FILE = utils.PathJoin(pathutils.XEN_CONFIG_DIR, "xend-config.sxp")

XL_CONFIG_FILE = utils.PathJoin(pathutils.XEN_CONFIG_DIR, "xen/xl.conf")

VIF_BRIDGE_SCRIPT = utils.PathJoin(pathutils.XEN_CONFIG_DIR,

                                   "scripts/vif-bridge")

_DOM0_NAME = "Domain-0"

_DISK_LETTERS = string.ascii_lowercase

_FILE_DRIVER_MAP = {

  constants.FD_LOOP: "file",

  constants.FD_BLKTAP: "tap:aio",

  constants.FD_BLKTAP2: "tap2:tapdisk:aio",

  }

def _CreateConfigCpus(cpu_mask):

  """Create a CPU config string for Xen's config file.

  """

  # Convert the string CPU mask to a list of list of int's

  cpu_list = utils.ParseMultiCpuMask(cpu_mask)

  if len(cpu_list) == 1:

    all_cpu_mapping = cpu_list[0]

    if all_cpu_mapping == constants.CPU_PINNING_OFF:

      # If CPU pinning has 1 entry that's "all", then remove the

      # parameter from the config file

      return None

    else:

      # If CPU pinning has one non-all entry, mapping all vCPUS (the entire

      # VM) to one physical CPU, using format 'cpu = "C"'

      return "cpu = \"%s\"" % ",".join(map(str, all_cpu_mapping))

  else:

    def _GetCPUMap(vcpu):

      if vcpu[0] == constants.CPU_PINNING_ALL_VAL:

        cpu_map = constants.CPU_PINNING_ALL_XEN

      else:

        cpu_map = ",".join(map(str, vcpu))

      return "\"%s\"" % cpu_map

    # build the result string in format 'cpus = [ "c", "c", "c" ]',

    # where each c is a physical CPU number, a range, a list, or any

    # combination

    return "cpus = [ %s ]" % ", ".join(map(_GetCPUMap, cpu_list))

def _RunInstanceList(fn, instance_list_errors):

  """Helper function for L{_GetInstanceList} to retrieve the list of instances

  from xen.

  @type fn: callable

  @param fn: Function to query xen for the list of instances

  @type instance_list_errors: list

  @param instance_list_errors: Error list

  @rtype: list

  """

  result = fn()

  if result.failed:

    logging.error("Retrieving the instance list from xen failed (%s): %s",

                  result.fail_reason, result.output)

    instance_list_errors.append(result)

    raise utils.RetryAgain()

  # skip over the heading

  return result.stdout.splitlines()

def _ParseInstanceList(lines, include_node):

  """Parses the output of listing instances by xen.

  @type lines: list

  @param lines: Result of retrieving the instance list from xen

  @type include_node: boolean

  @param include_node: If True, return information for Dom0

  @return: list of tuple containing (name, id, memory, vcpus, state, time

    spent)

  """

  result = []

  # Iterate through all lines while ignoring header

  for line in lines[1:]:

    # The format of lines is:

    # Name      ID Mem(MiB) VCPUs State  Time(s)

    # Domain-0   0  3418     4 r-----    266.2

    data = line.split()

    if len(data) != 6:

      raise errors.HypervisorError("Can't parse instance list,"

                                   " line: %s" % line)

    try:

      data[1] = int(data[1])

      data[2] = int(data[2])

      data[3] = int(data[3])

      data[5] = float(data[5])

    except (TypeError, ValueError), err:

      raise errors.HypervisorError("Can't parse instance list,"

                                   " line: %s, error: %s" % (line, err))

    # skip the Domain-0 (optional)

    if include_node or data[0] != _DOM0_NAME:

      result.append(data)

  return result

def _GetInstanceList(fn, include_node, _timeout=5):

  """Return the list of running instances.

  See L{_RunInstanceList} and L{_ParseInstanceList} for parameter details.

  """

  instance_list_errors = []

  try:

    lines = utils.Retry(_RunInstanceList, (0.3, 1.5, 1.0), _timeout,

                        args=(fn, instance_list_errors))

  except utils.RetryTimeout:

    if instance_list_errors:

      instance_list_result = instance_list_errors.pop()

      errmsg = ("listing instances failed, timeout exceeded (%s): %s" %

                (instance_list_result.fail_reason, instance_list_result.output))

    else:

      errmsg = "listing instances failed"

    raise errors.HypervisorError(errmsg)

  return _ParseInstanceList(lines, include_node)

def _IsInstanceRunning(instance_info):

  """Determine whether an instance is running.

  An instance is running if it is in the following Xen states:

  running, blocked, or paused.

  For some strange reason, Xen once printed 'rb----' which does not make any

  sense because an instance cannot be both running and blocked.  Fortunately,

  for Ganeti 'running' or 'blocked' is the same as 'running'.

  A state of nothing '------' means that the domain is runnable but it is not

  currently running.  That means it is in the queue behind other domains waiting

  to be scheduled to run.

  http://old-list-archives.xenproject.org/xen-users/2007-06/msg00849.html

  @type instance_info: string

  @param instance_info: Information about instance, as supplied by Xen.

  @rtype: bool

  @return: Whether an instance is running.

  """

  return instance_info == "r-----" \

      or instance_info == "rb----" \

      or instance_info == "-b----" \

      or instance_info == "--p---" \

      or instance_info == "------"

def _IsInstanceShutdown(instance_info):

  return instance_info == "---s--"

def _ParseNodeInfo(info):

  """Return information about the node.

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

        - memory_total: the total memory size on the node

        - memory_free: the available memory on the node for instances

        - nr_cpus: total number of CPUs

        - nr_nodes: in a NUMA system, the number of domains

        - nr_sockets: the number of physical CPU sockets in the node

        - hv_version: the hypervisor version in the form (major, minor)

  """

  result = {}

  cores_per_socket = threads_per_core = nr_cpus = None

  xen_major, xen_minor = None, None

  memory_total = None

  memory_free = None

  for line in info.splitlines():

    fields = line.split(":", 1)

    if len(fields) < 2:

      continue

    (key, val) = map(lambda s: s.strip(), fields)

    # Note: in Xen 3, memory has changed to total_memory

    if key in ("memory", "total_memory"):

      memory_total = int(val)

    elif key == "free_memory":

      memory_free = int(val)

    elif key == "nr_cpus":

      nr_cpus = result["cpu_total"] = int(val)

    elif key == "nr_nodes":

      result["cpu_nodes"] = int(val)

    elif key == "cores_per_socket":

      cores_per_socket = int(val)

    elif key == "threads_per_core":

      threads_per_core = int(val)

    elif key == "xen_major":

      xen_major = int(val)

    elif key == "xen_minor":

      xen_minor = int(val)

  if None not in [cores_per_socket, threads_per_core, nr_cpus]:

    result["cpu_sockets"] = nr_cpus / (cores_per_socket * threads_per_core)

  if memory_free is not None:

    result["memory_free"] = memory_free

  if memory_total is not None:

    result["memory_total"] = memory_total

  if not (xen_major is None or xen_minor is None):

    result[constants.HV_NODEINFO_KEY_VERSION] = (xen_major, xen_minor)

  return result

def _MergeInstanceInfo(info, instance_list):

  """Updates node information from L{_ParseNodeInfo} with instance info.

  @type info: dict

  @param info: Result from L{_ParseNodeInfo}

  @type instance_list: list of tuples

  @param instance_list: list of instance information; one tuple per instance

  @rtype: dict

  """

  total_instmem = 0

  for (name, _, mem, vcpus, _, _) in instance_list:

    if name == _DOM0_NAME:

      info["memory_dom0"] = mem

      info["cpu_dom0"] = vcpus

    # Include Dom0 in total memory usage

    total_instmem += mem

  memory_free = info.get("memory_free")

  memory_total = info.get("memory_total")

  # Calculate memory used by hypervisor

  if None not in [memory_total, memory_free, total_instmem]:

    info["memory_hv"] = memory_total - memory_free - total_instmem

  return info

def _GetNodeInfo(info, instance_list):

  """Combines L{_MergeInstanceInfo} and L{_ParseNodeInfo}.

  @type instance_list: list of tuples

  @param instance_list: list of instance information; one tuple per instance

  """

  return _MergeInstanceInfo(_ParseNodeInfo(info), instance_list)

def _GetConfigFileDiskData(block_devices, blockdev_prefix,

                           _letters=_DISK_LETTERS):

  """Get disk directives for Xen config file.

  This method builds the xen config disk directive according to the

  given disk_template and block_devices.

  @param block_devices: list of tuples (cfdev, rldev):

      - cfdev: dict containing ganeti config disk part

      - rldev: ganeti.block.bdev.BlockDev object

  @param blockdev_prefix: a string containing blockdevice prefix,

                          e.g. "sd" for /dev/sda

  @return: string containing disk directive for xen instance config file

  """

  if len(block_devices) > len(_letters):

    raise errors.HypervisorError("Too many disks")

  disk_data = []

  for sd_suffix, (cfdev, dev_path, _) in zip(_letters, block_devices):

    sd_name = blockdev_prefix + sd_suffix

    if cfdev.mode == constants.DISK_RDWR:

      mode = "w"

    else:

      mode = "r"

    if cfdev.dev_type in [constants.DT_FILE, constants.DT_SHARED_FILE]:

      driver = _FILE_DRIVER_MAP[cfdev.logical_id[0]]

    else:

      driver = "phy"

    disk_data.append("'%s:%s,%s,%s'" % (driver, dev_path, sd_name, mode))

  return disk_data

def _QuoteCpuidField(data):

  """Add quotes around the CPUID field only if necessary.

  Xen CPUID fields come in two shapes: LIBXL strings, which need quotes around

  them, and lists of XEND strings, which don't.

  @param data: Either type of parameter.

  @return: The quoted version thereof.

  """

  return "'%s'" % data if data.startswith("host") else data

class XenHypervisor(hv_base.BaseHypervisor):

  """Xen generic hypervisor interface

  This is the Xen base class used for both Xen PVM and HVM. It contains

  all the functionality that is identical for both.

  """

  CAN_MIGRATE = True

  REBOOT_RETRY_COUNT = 60

  REBOOT_RETRY_INTERVAL = 10

  _ROOT_DIR = pathutils.RUN_DIR + "/xen-hypervisor"

  _NICS_DIR = _ROOT_DIR + "/nic" # contains NICs' info

  _DIRS = [_ROOT_DIR, _NICS_DIR]

  ANCILLARY_FILES = [

    XEND_CONFIG_FILE,

    XL_CONFIG_FILE,

    VIF_BRIDGE_SCRIPT,

    ]

  ANCILLARY_FILES_OPT = [

    XL_CONFIG_FILE,

    ]

  def __init__(self, _cfgdir=None, _run_cmd_fn=None, _cmd=None):

    hv_base.BaseHypervisor.__init__(self)

    if _cfgdir is None:

      self._cfgdir = pathutils.XEN_CONFIG_DIR

    else:

      self._cfgdir = _cfgdir

    if _run_cmd_fn is None:

      self._run_cmd_fn = utils.RunCmd

    else:

      self._run_cmd_fn = _run_cmd_fn

    self._cmd = _cmd

  @staticmethod

  def _GetCommandFromHvparams(hvparams):

    """Returns the Xen command extracted from the given hvparams.

    @type hvparams: dict of strings

    @param hvparams: hypervisor parameters

    """

    if hvparams is None or constants.HV_XEN_CMD not in hvparams:

      raise errors.HypervisorError("Cannot determine xen command.")

    else:

      return hvparams[constants.HV_XEN_CMD]

  def _GetCommand(self, hvparams):

    """Returns Xen command to use.

    @type hvparams: dict of strings

    @param hvparams: hypervisor parameters

    """

    if self._cmd is None:

      cmd = XenHypervisor._GetCommandFromHvparams(hvparams)

    else:

      cmd = self._cmd

    if cmd not in constants.KNOWN_XEN_COMMANDS:

      raise errors.ProgrammerError("Unknown Xen command '%s'" % cmd)

    return cmd

  def _RunXen(self, args, hvparams, timeout=None):

    """Wrapper around L{utils.process.RunCmd} to run Xen command.

    @type hvparams: dict of strings

    @param hvparams: dictionary of hypervisor params

    @type timeout: int or None

    @param timeout: if a timeout (in seconds) is specified, the command will be

                    terminated after that number of seconds.

    @see: L{utils.process.RunCmd}

    """

    cmd = []

    if timeout is not None:

      cmd.extend(["timeout", str(timeout)])

    cmd.extend([self._GetCommand(hvparams)])

    cmd.extend(args)

    return self._run_cmd_fn(cmd)

  def _ConfigFileName(self, instance_name):

    """Get the config file name for an instance.

    @param instance_name: instance name

    @type instance_name: str

    @return: fully qualified path to instance config file

    @rtype: str

    """

    return utils.PathJoin(self._cfgdir, instance_name)

  @classmethod

  def _WriteNICInfoFile(cls, instance, idx, nic):

    """Write the Xen config file for the instance.

    This version of the function just writes the config file from static data.

    """

    instance_name = instance.name

    dirs = [(dname, constants.RUN_DIRS_MODE)

            for dname in cls._DIRS + [cls._InstanceNICDir(instance_name)]]

    utils.EnsureDirs(dirs)

    cfg_file = cls._InstanceNICFile(instance_name, idx)

    data = StringIO()

    data.write("TAGS=%s\n" % r"\ ".join(instance.GetTags()))

    if nic.netinfo:

      netinfo = objects.Network.FromDict(nic.netinfo)

      for k, v in netinfo.HooksDict().iteritems():

        data.write("%s=%s\n" % (k, v))

    data.write("MAC=%s\n" % nic.mac)

    if nic.ip:

      data.write("IP=%s\n" % nic.ip)

    data.write("INTERFACE_INDEX=%s\n" % str(idx))

    if nic.name:

      data.write("INTERFACE_NAME=%s\n" % nic.name)

    data.write("INTERFACE_UUID=%s\n" % nic.uuid)

    data.write("MODE=%s\n" % nic.nicparams[constants.NIC_MODE])

    data.write("LINK=%s\n" % nic.nicparams[constants.NIC_LINK])

    data.write("VLAN=%s\n" % nic.nicparams[constants.NIC_VLAN])

    try:

      utils.WriteFile(cfg_file, data=data.getvalue())

    except EnvironmentError, err:

      raise errors.HypervisorError("Cannot write Xen instance configuration"

                                   " file %s: %s" % (cfg_file, err))

  @classmethod

  def _InstanceNICDir(cls, instance_name):

    """Returns the directory holding the tap device files for a given instance.

    """

    return utils.PathJoin(cls._NICS_DIR, instance_name)

  @classmethod

  def _InstanceNICFile(cls, instance_name, seq):

    """Returns the name of the file containing the tap device for a given NIC

    """

    return utils.PathJoin(cls._InstanceNICDir(instance_name), str(seq))

  @classmethod

  def _GetConfig(cls, instance, startup_memory, block_devices):

    """Build Xen configuration for an instance.

    """

    raise NotImplementedError

  def _WriteNicConfig(self, config, instance, hvp):

    vif_data = []

    # only XenHvmHypervisor has these hvparams

    nic_type = hvp.get(constants.HV_NIC_TYPE, None)

    vif_type = hvp.get(constants.HV_VIF_TYPE, None)

    nic_type_str = ""

    if nic_type or vif_type:

      if nic_type is None:

        if vif_type:

          nic_type_str = ", type=%s" % vif_type

      elif nic_type == constants.HT_NIC_PARAVIRTUAL:

        nic_type_str = ", type=paravirtualized"

      else:

        # parameter 'model' is only valid with type 'ioemu'

        nic_type_str = ", model=%s, type=%s" % \

          (nic_type, constants.HT_HVM_VIF_IOEMU)

    for idx, nic in enumerate(instance.nics):

      nic_str = "mac=%s%s" % (nic.mac, nic_type_str)

      ip = getattr(nic, "ip", None)

      if ip is not None:

        nic_str += ", ip=%s" % ip

      if nic.nicparams[constants.NIC_MODE] == constants.NIC_MODE_BRIDGED:

        nic_str += ", bridge=%s" % nic.nicparams[constants.NIC_LINK]

      elif nic.nicparams[constants.NIC_MODE] == constants.NIC_MODE_OVS:

        nic_str += ", bridge=%s" % nic.nicparams[constants.NIC_LINK]

        if nic.nicparams[constants.NIC_VLAN]:

          nic_str += "%s" % nic.nicparams[constants.NIC_VLAN]

      if hvp[constants.HV_VIF_SCRIPT]:

        nic_str += ", script=%s" % hvp[constants.HV_VIF_SCRIPT]

      vif_data.append("'%s'" % nic_str)

      self._WriteNICInfoFile(instance, idx, nic)

    config.write("vif = [%s]\n" % ",".join(vif_data))

  def _WriteConfigFile(self, instance_name, data):

    """Write the Xen config file for the instance.

    This version of the function just writes the config file from static data.

    """

    # just in case it exists

    utils.RemoveFile(utils.PathJoin(self._cfgdir, "auto", instance_name))

    cfg_file = self._ConfigFileName(instance_name)

    try:

      utils.WriteFile(cfg_file, data=data)

    except EnvironmentError, err:

      raise errors.HypervisorError("Cannot write Xen instance configuration"

                                   " file %s: %s" % (cfg_file, err))

  def _ReadConfigFile(self, instance_name):

    """Returns the contents of the instance config file.

    """

    filename = self._ConfigFileName(instance_name)

    try:

      file_content = utils.ReadFile(filename)

    except EnvironmentError, err:

      raise errors.HypervisorError("Failed to load Xen config file: %s" % err)

    return file_content

  def _RemoveConfigFile(self, instance_name):

    """Remove the xen configuration file.

    """

    utils.RemoveFile(self._ConfigFileName(instance_name))

    try:

      shutil.rmtree(self._InstanceNICDir(instance_name))

    except OSError, err:

      if err.errno != errno.ENOENT:

        raise

  def _StashConfigFile(self, instance_name):

    """Move the Xen config file to the log directory and return its new path.

    """

    old_filename = self._ConfigFileName(instance_name)

    base = ("%s-%s" %

            (instance_name, utils.TimestampForFilename()))

    new_filename = utils.PathJoin(pathutils.LOG_XEN_DIR, base)

    utils.RenameFile(old_filename, new_filename)

    return new_filename

  def _GetInstanceList(self, include_node, hvparams):

    """Wrapper around module level L{_GetInstanceList}.

    @type hvparams: dict of strings

    @param hvparams: hypervisor parameters to be used on this node

    """

    return _GetInstanceList(lambda: self._RunXen(["list"], hvparams),

                            include_node)

  def ListInstances(self, hvparams=None):

    """Get the list of running instances.

    """

    instance_list = self._GetInstanceList(False, hvparams)

    names = [info[0] for info in instance_list]

    return names

  def GetInstanceInfo(self, instance_name, hvparams=None):

    """Get instance properties.

    @type instance_name: string

    @param instance_name: the instance name

    @type hvparams: dict of strings

    @param hvparams: the instance's hypervisor params

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

    """

    instance_list = self._GetInstanceList(instance_name == _DOM0_NAME, hvparams)

    result = None

    for data in instance_list:

      if data[0] == instance_name:

        result = data

        break

    return result

  def GetAllInstancesInfo(self, hvparams=None):

    """Get properties of all instances.

    @type hvparams: dict of strings

    @param hvparams: hypervisor parameters

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

    """

    return self._GetInstanceList(False, hvparams)

  def _MakeConfigFile(self, instance, startup_memory, block_devices):

    """Gather configuration details and write to disk.

    See L{_GetConfig} for arguments.

    """

    buf = StringIO()

    buf.write("# Automatically generated by Ganeti. Do not edit!\n")

    buf.write("\n")

    buf.write(self._GetConfig(instance, startup_memory, block_devices))

    buf.write("\n")

    self._WriteConfigFile(instance.name, buf.getvalue())

  def StartInstance(self, instance, block_devices, startup_paused):

    """Start an instance.

    """

    startup_memory = self._InstanceStartupMemory(instance)

    self._MakeConfigFile(instance, startup_memory, block_devices)

    cmd = ["create"]

    if startup_paused:

      cmd.append("-p")

    cmd.append(self._ConfigFileName(instance.name))

    result = self._RunXen(cmd, instance.hvparams)

    if result.failed:

      # Move the Xen configuration file to the log directory to avoid

      # leaving a stale config file behind.

      stashed_config = self._StashConfigFile(instance.name)

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

                                   " config file to %s" %

                                   (instance.name, result.fail_reason,

                                    result.output, stashed_config))

  def StopInstance(self, instance, force=False, retry=False, name=None,

                   timeout=None):

    """Stop an instance.

    A soft shutdown can be interrupted. A hard shutdown tries forever.

    """

    assert(timeout is None or force is not None)

    if name is None:

      name = instance.name

    return self._StopInstance(name, force, instance.hvparams, timeout)

  def _ShutdownInstance(self, name, hvparams, timeout):

    """Shutdown an instance if the instance is running.

    The '-w' flag waits for shutdown to complete which avoids the need

    to poll in the case where we want to destroy the domain

    immediately after shutdown.

    @type name: string

    @param name: name of the instance to stop

    @type hvparams: dict of string

    @param hvparams: hypervisor parameters of the instance

    @type timeout: int or None

    @param timeout: a timeout after which the shutdown command should be killed,

                    or None for no timeout

    """

    instance_info = self.GetInstanceInfo(name, hvparams=hvparams)

    if instance_info is None or _IsInstanceShutdown(instance_info[4]):

      logging.info("Failed to shutdown instance %s, not running", name)

      return None

    return self._RunXen(["shutdown", "-w", name], hvparams, timeout)

  def _DestroyInstance(self, name, hvparams):

    """Destroy an instance if the instance if the instance exists.

    @type name: string

    @param name: name of the instance to destroy

    @type hvparams: dict of string

    @param hvparams: hypervisor parameters of the instance

    """

    instance_info = self.GetInstanceInfo(name, hvparams=hvparams)

    if instance_info is None:

      logging.info("Failed to destroy instance %s, does not exist", name)

      return None

    return self._RunXen(["destroy", name], hvparams)

  def _StopInstance(self, name, force, hvparams, timeout):

    """Stop an instance.

    @type name: string

    @param name: name of the instance to destroy

    @type force: boolean

    @param force: whether to do a "hard" stop (destroy)

    @type hvparams: dict of string

    @param hvparams: hypervisor parameters of the instance

    @type timeout: int or None

    @param timeout: a timeout after which the shutdown command should be killed,

                    or None for no timeout

    """

    if force:

      result = self._DestroyInstance(name, hvparams)

    else:

      self._ShutdownInstance(name, hvparams, timeout)

      result = self._DestroyInstance(name, hvparams)

    if result is not None and result.failed and \

          self.GetInstanceInfo(name, hvparams=hvparams) is not None:

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

                                   (name, result.fail_reason, result.output))

    # Remove configuration file if stopping/starting instance was successful

    self._RemoveConfigFile(name)

  def RebootInstance(self, instance):

    """Reboot an instance.

    """

    ini_info = self.GetInstanceInfo(instance.name, hvparams=instance.hvparams)

    if ini_info is None:

      raise errors.HypervisorError("Failed to reboot instance %s,"

                                   " not running" % instance.name)

    result = self._RunXen(["reboot", instance.name], instance.hvparams)

    if result.failed:

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

                                   (instance.name, result.fail_reason,

                                    result.output))

    def _CheckInstance():

      new_info = self.GetInstanceInfo(instance.name, hvparams=instance.hvparams)

      # check if the domain ID has changed or the run time has decreased

      if (new_info is not None and

          (new_info[1] != ini_info[1] or new_info[5] < ini_info[5])):

        return

      raise utils.RetryAgain()

    try:

      utils.Retry(_CheckInstance, self.REBOOT_RETRY_INTERVAL,

                  self.REBOOT_RETRY_INTERVAL * self.REBOOT_RETRY_COUNT)

    except utils.RetryTimeout:

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

                                   " did not reboot in the expected interval" %

                                   (instance.name, ))

  def BalloonInstanceMemory(self, instance, mem):

    """Balloon an instance memory to a certain value.

    @type instance: L{objects.Instance}

    @param instance: instance to be accepted

    @type mem: int

    @param mem: actual memory size to use for instance runtime

    """

    result = self._RunXen(["mem-set", instance.name, mem], instance.hvparams)

    if result.failed:

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

                                   (instance.name, result.fail_reason,

                                    result.output))

    # Update configuration file

    cmd = ["sed", "-ie", "s/^memory.*$/memory = %s/" % mem]

    cmd.append(self._ConfigFileName(instance.name))

    result = utils.RunCmd(cmd)

    if result.failed:

      raise errors.HypervisorError("Failed to update memory for %s: %s (%s)" %

                                   (instance.name, result.fail_reason,

                                    result.output))

  def GetNodeInfo(self, hvparams=None):

    """Return information about the node.

    @see: L{_GetNodeInfo} and L{_ParseNodeInfo}

    """

    result = self._RunXen(["info"], hvparams)

    if result.failed:

      logging.error("Can't retrieve xen hypervisor information (%s): %s",

                    result.fail_reason, result.output)

      return None

    instance_list = self._GetInstanceList(True, hvparams)

    return _GetNodeInfo(result.stdout, instance_list)

  @classmethod

  def GetInstanceConsole(cls, instance, primary_node, hvparams, beparams):

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

    """

    xen_cmd = XenHypervisor._GetCommandFromHvparams(hvparams)

    return objects.InstanceConsole(instance=instance.name,

                                   kind=constants.CONS_SSH,

                                   host=primary_node.name,

                                   user=constants.SSH_CONSOLE_USER,

                                   command=[pathutils.XEN_CONSOLE_WRAPPER,

                                            xen_cmd, instance.name])

  def Verify(self, hvparams=None):

    """Verify the hypervisor.

    For Xen, this verifies that the xend process is running.

    @type hvparams: dict of strings

    @param hvparams: hypervisor parameters to be verified against

    @return: Problem description if something is wrong, C{None} otherwise

    """

    if hvparams is None:

      return "Could not verify the hypervisor, because no hvparams were" \

             " provided."

    if constants.HV_XEN_CMD in hvparams:

      xen_cmd = hvparams[constants.HV_XEN_CMD]

      try:

        self._CheckToolstack(xen_cmd)

      except errors.HypervisorError:

        return "The configured xen toolstack '%s' is not available on this" \

               " node." % xen_cmd

    result = self._RunXen(["info"], hvparams)

    if result.failed:

      return "Retrieving information from xen failed: %s, %s" % \

        (result.fail_reason, result.output)

    return None

  def MigrationInfo(self, instance):

    """Get instance information to perform a migration.

    @type instance: L{objects.Instance}

    @param instance: instance to be migrated

    @rtype: string

    @return: content of the xen config file

    """

    return self._ReadConfigFile(instance.name)

  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: content of the xen config file on the source node

    @type target: string

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

    """

    pass

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

    """Finalize an instance migration.

    After a successful migration we write the xen config file.

    We do nothing on a failure, as we did not change anything at accept time.

    @type instance: L{objects.Instance}

    @param instance: instance whose migration is being finalized

    @type info: string

    @param info: content of the xen config file on the source node

    @type success: boolean

    @param success: whether the migration was a success or a failure

    """

    if success:

      self._WriteConfigFile(instance.name, info)

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

    """Migrate an instance to a target node.

    The migration will not be attempted if the instance is not

    currently running.

    @type instance: L{objects.Instance}

    @param instance: the instance to be migrated

    @type target: string

    @param target: ip address of the target node

    @type live: boolean

    @param live: perform a live migration

    """

    port = instance.hvparams[constants.HV_MIGRATION_PORT]

    return self._MigrateInstance(cluster_name, instance.name, target, port,

                                 live, instance.hvparams)

  def _MigrateInstance(self, cluster_name, instance_name, target, port, live,

                       hvparams, _ping_fn=netutils.TcpPing):

    """Migrate an instance to a target node.

    @see: L{MigrateInstance} for details

    """

    if hvparams is None:

      raise errors.HypervisorError("No hvparams provided.")

    if self.GetInstanceInfo(instance_name, hvparams=hvparams) is None:

      raise errors.HypervisorError("Instance not running, cannot migrate")

    cmd = self._GetCommand(hvparams)

    if (cmd == constants.XEN_CMD_XM and

        not _ping_fn(target, port, live_port_needed=True)):

      raise errors.HypervisorError("Remote host %s not listening on port"

                                   " %s, cannot migrate" % (target, port))

    args = ["migrate"]

    if cmd == constants.XEN_CMD_XM:

      args.extend(["-p", "%d" % port])

      if live:

        args.append("-l")

    elif cmd == constants.XEN_CMD_XL:

      args.extend([

        "-s", constants.XL_SSH_CMD % cluster_name,

        "-C", self._ConfigFileName(instance_name),

        ])

    else:

      raise errors.HypervisorError("Unsupported Xen command: %s" % self._cmd)

    args.extend([instance_name, target])

    result = self._RunXen(args, hvparams)

    if result.failed:

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

                                   (instance_name, result.output))

  def FinalizeMigrationSource(self, instance, success, live):

    """Finalize the instance migration on the source node.

    @type instance: L{objects.Instance}

    @param instance: the instance that was migrated

    @type success: bool

    @param success: whether the migration succeeded or not

    @type live: bool

    @param live: whether the user requested a live migration or not

    """

    # pylint: disable=W0613

    if success:

      # remove old xen file after migration succeeded

      try:

        self._RemoveConfigFile(instance.name)

      except EnvironmentError:

        logging.exception("Failure while removing instance config file")

  def GetMigrationStatus(self, instance):

    """Get the migration status

    As MigrateInstance for Xen is still blocking, if this method is called it

    means that MigrateInstance has completed successfully. So we can safely

    assume that the migration was successful and notify this fact to the client.

    @type instance: L{objects.Instance}

    @param instance: the instance that is being migrated

    @rtype: L{objects.MigrationStatus}

    @return: the status of the current migration (one of

             L{constants.HV_MIGRATION_VALID_STATUSES}), plus any additional

             progress info that can be retrieved from the hypervisor

    """

    return objects.MigrationStatus(status=constants.HV_MIGRATION_COMPLETED)

  def PowercycleNode(self, hvparams=None):