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#!/usr/bin/python

#

# Copyright (C) 2006, 2007 Google Inc.

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.

"""Module that abstracts the virtualisation interface

"""

import time

import os

from cStringIO import StringIO

from ganeti import utils

from ganeti import logger

from ganeti import ssconf

from ganeti.errors import HypervisorError

_HT_XEN30 = "xen-3.0"

_HT_FAKE = "fake"

VALID_HTYPES = (_HT_XEN30, _HT_FAKE)

def GetHypervisor():

  """Return a Hypervisor instance.

  This function parses the cluster hypervisor configuration file and

  instantiates a class based on the value of this file.

  """

  ht_kind = ssconf.SimpleStore().GetHypervisorType()

  if ht_kind == _HT_XEN30:

    cls = XenHypervisor

  elif ht_kind == _HT_FAKE:

    cls = FakeHypervisor

  else:

    raise HypervisorError, "Unknown hypervisor type '%s'" % ht_kind

  return cls()

class BaseHypervisor(object):

  """Abstract virtualisation technology interface

  The goal is that all aspects of the virtualisation technology must

  be abstracted away from the rest of code.

  """

  def __init__(self):

    pass

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

    """Start an instance."""

    raise NotImplementedError

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

    """Stop an instance."""

    raise NotImplementedError

  def ListInstances(self):

    """Get the list of running instances."""

    raise NotImplementedError

  def GetInstanceInfo(self, instance_name):

    """Get instance properties.

    Args:

      instance_name: the instance name

    Returns:

      (name, id, memory, vcpus, state, times)

    """

    raise NotImplementedError

  def GetAllInstancesInfo(self):

    """Get properties of all instances.

    Returns:

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

    """

    raise NotImplementedError

  def GetNodeInfo(self):

    """Return information about the node.

    The return value is a dict, which has to have the following items:

      (all 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

    """

    raise NotImplementedError

  @staticmethod

  def GetShellCommandForConsole(instance_name):

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

    """

    raise NotImplementedError

  def Verify(self):

    """Verify the hypervisor.

    """

    raise NotImplementedError

class XenHypervisor(BaseHypervisor):

  """Xen hypervisor interface"""

  @staticmethod

  def _WriteConfigFile(instance, block_devices, extra_args):

    """Create a Xen 3.0 config file.

    """

    config = StringIO()

    config.write("# this is autogenerated by Ganeti, please do not edit\n#\n")

    config.write("kernel = '/boot/vmlinuz-2.6-xenU'\n")

    config.write("memory = %d\n" % instance.memory)

    config.write("vcpus = %d\n" % instance.vcpus)

    config.write("name = '%s'\n" % instance.name)

    vif_data = []

    for nic in instance.nics:

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

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

      if ip is not None:

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

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

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

    disk_data = ["'phy:%s,%s,w'" % (rldev.dev_path, cfdev.iv_name)

                 for cfdev, rldev in block_devices]

    config.write("disk = [%s]\n" % ",".join(disk_data))

    config.write("root = '/dev/sda ro'\n")

    config.write("on_poweroff = 'destroy'\n")

    config.write("on_reboot = 'restart'\n")

    config.write("on_crash = 'restart'\n")

    if extra_args:

      config.write("extra = '%s'\n" % extra_args)

    # just in case it exists

    utils.RemoveFile("/etc/xen/auto/%s" % instance.name)

    f = open("/etc/xen/%s" % instance.name, "w")

    f.write(config.getvalue())

    f.close()

    return True

  @staticmethod

  def _RemoveConfigFile(instance):

    """Remove the xen configuration file.

    """

    utils.RemoveFile("/etc/xen/%s" % instance.name)

  @staticmethod

  def _GetXMList(include_node):

    """Return the list of running instances.

    If the `include_node` argument is True, then we return information

    for dom0 also, otherwise we filter that from the return value.

    The return value is a list of (name, id, memory, vcpus, state, time spent)

    """

    for dummy in range(5):

      result = utils.RunCmd(["xm", "list"])

      if not result.failed:

        break

      logger.Error("xm list failed (%s): %s" % (result.fail_reason,

                                                result.output))

      time.sleep(1)

    if result.failed:

      raise HypervisorError("xm list failed, retries exceeded (%s): %s" %

                            (result.fail_reason, result.stderr))

    # skip over the heading and the domain 0 line (optional)

    if include_node:

      to_skip = 1

    else:

      to_skip = 2

    lines = result.stdout.splitlines()[to_skip:]

    result = []

    for line in lines:

      # 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 HypervisorError("Can't parse output of xm 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 ValueError, err:

        raise HypervisorError("Can't parse output of xm list,"

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

      result.append(data)

    return result

  def ListInstances(self):

    """Get the list of running instances.

    """

    xm_list = self._GetXMList(False)

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

    return names

  def GetInstanceInfo(self, instance_name):

    """Get instance properties.

    Args:

      instance_name: the instance name

    Returns:

      (name, id, memory, vcpus, stat, times)

    """

    xm_list = self._GetXMList(instance_name=="Domain-0")

    result = None

    for data in xm_list:

      if data[0] == instance_name:

        result = data

        break

    return result

  def GetAllInstancesInfo(self):

    """Get properties of all instances.

    Returns:

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

    """

    xm_list = self._GetXMList(False)

    return xm_list

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

    """Start an instance."""

    self._WriteConfigFile(instance, block_devices, extra_args)

    result = utils.RunCmd(["xm", "create", instance.name])

    if result.failed:

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

                            (instance.name, result.fail_reason))

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

    """Stop an instance."""

    self._RemoveConfigFile(instance)

    if force:

      command = ["xm", "destroy", instance.name]

    else:

      command = ["xm", "shutdown", instance.name]

    result = utils.RunCmd(command)

    if result.failed:

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

                            (instance.name, result.fail_reason))

  def GetNodeInfo(self):

    """Return information about the node.

    The return value is a dict, which has to have the following items:

      (all 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

    """

    # note: in xen 3, memory has changed to total_memory

    result = utils.RunCmd(["xm", "info"])

    if result.failed:

      logger.Error("Can't run 'xm info': %s" % result.fail_reason)

      return None

    xmoutput = result.stdout.splitlines()

    result = {}

    for line in xmoutput:

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

      if len(splitfields) > 1:

        key = splitfields[0].strip()

        val = splitfields[1].strip()

        if key == 'memory' or key == 'total_memory':

          result['memory_total'] = int(val)

        elif key == 'free_memory':

          result['memory_free'] = int(val)

    dom0_info = self.GetInstanceInfo("Domain-0")

    if dom0_info is not None:

      result['memory_dom0'] = dom0_info[2]

    return result

  @staticmethod

  def GetShellCommandForConsole(instance_name):

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

    """

    return "xm console %s" % instance_name

  def Verify(self):

    """Verify the hypervisor.

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

    """

    if not utils.CheckDaemonAlive('/var/run/xend.pid', 'xend'):

      return "xend daemon is not running"

class FakeHypervisor(BaseHypervisor):

  """Fake hypervisor interface.

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

  a real virtualisation software installed.

  """

  _ROOT_DIR = "/var/run/ganeti-fake-hypervisor"

  def __init__(self):

    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.

    Args:

      instance_name: the instance name

    Returns:

      (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 = file(file_name, "r")

      try:

        inst_id = fh.readline().strip()

        memory = fh.readline().strip()

        vcpus = fh.readline().strip()

        stat = "---b-"

        times = "0"

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

      finally:

        fh.close()

    except IOError, err:

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

                            (instance_name, err))

  def GetAllInstancesInfo(self):

    """Get properties of all instances.

    Returns:

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

    """

    data = []

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

      try:

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

        inst_id = "-1"

        memory = "0"

        stat = "-----"

        times = "-1"

        try:

          inst_id = fh.readline().strip()

          memory = fh.readline().strip()

          vcpus = fh.readline().strip()

          stat = "---b-"

          times = "0"

        finally:

          fh.close()

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

      except IOError, err:

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

    return data

  def StartInstance(self, instance, force, extra_args):

    """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.

    """

    file_name = self._ROOT_DIR + "/%s" % instance.name

    if os.path.exists(file_name):

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

                            (instance.name, "already running"))

    try:

      fh = file(file_name, "w")

      try:

        fh.write("0\n%d\n%d\n" % (instance.memory, instance.vcpus))

      finally:

        fh.close()

    except IOError, err:

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

                            (instance.name, err))

  def StopInstance(self, instance, force=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.

    """

    file_name = self._ROOT_DIR + "/%s" % instance.name

    if not os.path.exists(file_name):

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

                            (instance.name, "not running"))

    utils.RemoveFile(file_name)

  def GetNodeInfo(self):

    """Return information about the node.

    The return value is a dict, which has to have the following items:

      (all 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

    """

    # global ram usage from the xm info command

    # memory                 : 3583

    # free_memory            : 747

    # note: in xen 3, memory has changed to total_memory

    try:

      fh = file("/proc/meminfo")

      try:

        data = fh.readlines()

      finally:

        fh.close()

    except IOError, err:

      raise HypervisorError("Failed to list node info: %s" % err)

    result = {}

    sum_free = 0

    for line in data:

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

      if len(splitfields) > 1:

        key = splitfields[0].strip()

        val = splitfields[1].strip()

        if key == 'MemTotal':

          result['memory_total'] = int(val.split()[0])/1024

        elif key in ('MemFree', 'Buffers', 'Cached'):

          sum_free += int(val.split()[0])/1024

        elif key == 'Active':

          result['memory_dom0'] = int(val.split()[0])/1024

    result['memory_free'] = sum_free

    return result

  @staticmethod

  def GetShellCommandForConsole(instance_name):

    """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