Synnefo » snf-ganeti

#

#

# Copyright (C) 2010 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.

"""Ganeti RAPI client."""

# No Ganeti-specific modules should be imported. The RAPI client is supposed to

# be standalone.

import httplib

import urllib2

import logging

import simplejson

import socket

import urllib

import OpenSSL

import distutils.version

GANETI_RAPI_PORT = 5080

GANETI_RAPI_VERSION = 2

HTTP_DELETE = "DELETE"

HTTP_GET = "GET"

HTTP_PUT = "PUT"

HTTP_POST = "POST"

HTTP_OK = 200

HTTP_NOT_FOUND = 404

HTTP_APP_JSON = "application/json"

REPLACE_DISK_PRI = "replace_on_primary"

REPLACE_DISK_SECONDARY = "replace_on_secondary"

REPLACE_DISK_CHG = "replace_new_secondary"

REPLACE_DISK_AUTO = "replace_auto"

NODE_ROLE_DRAINED = "drained"

NODE_ROLE_MASTER_CANDIATE = "master-candidate"

NODE_ROLE_MASTER = "master"

NODE_ROLE_OFFLINE = "offline"

NODE_ROLE_REGULAR = "regular"

# Internal constants

_REQ_DATA_VERSION_FIELD = "__version__"

_INST_CREATE_REQV1 = "instance-create-reqv1"

class Error(Exception):

  """Base error class for this module.

  """

  pass

class CertificateError(Error):

  """Raised when a problem is found with the SSL certificate.

  """

  pass

class GanetiApiError(Error):

  """Generic error raised from Ganeti API.

  """

  def __init__(self, msg, code=None):

    Error.__init__(self, msg)

    self.code = code

def FormatX509Name(x509_name):

  """Formats an X509 name.

  @type x509_name: OpenSSL.crypto.X509Name

  """

  try:

    # Only supported in pyOpenSSL 0.7 and above

    get_components_fn = x509_name.get_components

  except AttributeError:

    return repr(x509_name)

  else:

    return "".join("/%s=%s" % (name, value)

                   for name, value in get_components_fn())

class CertAuthorityVerify:

  """Certificate verificator for SSL context.

  Configures SSL context to verify server's certificate.

  """

  _CAPATH_MINVERSION = "0.9"

  _DEFVFYPATHS_MINVERSION = "0.9"

  _PYOPENSSL_VERSION = OpenSSL.__version__

  _PARSED_PYOPENSSL_VERSION = distutils.version.LooseVersion(_PYOPENSSL_VERSION)

  _SUPPORT_CAPATH = (_PARSED_PYOPENSSL_VERSION >= _CAPATH_MINVERSION)

  _SUPPORT_DEFVFYPATHS = (_PARSED_PYOPENSSL_VERSION >= _DEFVFYPATHS_MINVERSION)

  def __init__(self, cafile=None, capath=None, use_default_verify_paths=False):

    """Initializes this class.

    @type cafile: string

    @param cafile: In which file we can find the certificates

    @type capath: string

    @param capath: In which directory we can find the certificates

    @type use_default_verify_paths: bool

    @param use_default_verify_paths: Whether the platform provided CA

                                     certificates are to be used for

                                     verification purposes

    """

    self._cafile = cafile

    self._capath = capath

    self._use_default_verify_paths = use_default_verify_paths

    if self._capath is not None and not self._SUPPORT_CAPATH:

      raise Error(("PyOpenSSL %s has no support for a CA directory,"

                   " version %s or above is required") %

                  (self._PYOPENSSL_VERSION, self._CAPATH_MINVERSION))

    if self._use_default_verify_paths and not self._SUPPORT_DEFVFYPATHS:

      raise Error(("PyOpenSSL %s has no support for using default verification"

                   " paths, version %s or above is required") %

                  (self._PYOPENSSL_VERSION, self._DEFVFYPATHS_MINVERSION))

  @staticmethod

  def _VerifySslCertCb(logger, _, cert, errnum, errdepth, ok):

    """Callback for SSL certificate verification.

    @param logger: Logging object

    """

    if ok:

      log_fn = logger.debug

    else:

      log_fn = logger.error

    log_fn("Verifying SSL certificate at depth %s, subject '%s', issuer '%s'",

           errdepth, FormatX509Name(cert.get_subject()),

           FormatX509Name(cert.get_issuer()))

    if not ok:

      try:

        # Only supported in pyOpenSSL 0.7 and above

        # pylint: disable-msg=E1101

        fn = OpenSSL.crypto.X509_verify_cert_error_string

      except AttributeError:

        errmsg = ""

      else:

        errmsg = ":%s" % fn(errnum)

      logger.error("verify error:num=%s%s", errnum, errmsg)

    return ok

  def __call__(self, ctx, logger):

    """Configures an SSL context to verify certificates.

    @type ctx: OpenSSL.SSL.Context

    @param ctx: SSL context

    """

    if self._use_default_verify_paths:

      ctx.set_default_verify_paths()

    if self._cafile or self._capath:

      if self._SUPPORT_CAPATH:

        ctx.load_verify_locations(self._cafile, self._capath)

      else:

        ctx.load_verify_locations(self._cafile)

    ctx.set_verify(OpenSSL.SSL.VERIFY_PEER,

                   lambda conn, cert, errnum, errdepth, ok: \

                     self._VerifySslCertCb(logger, conn, cert,

                                           errnum, errdepth, ok))

class _HTTPSConnectionOpenSSL(httplib.HTTPSConnection):

  """HTTPS Connection handler that verifies the SSL certificate.

  """

  def __init__(self, *args, **kwargs):

    """Initializes this class.

    """

    httplib.HTTPSConnection.__init__(self, *args, **kwargs)

    self._logger = None

    self._config_ssl_verification = None

  def Setup(self, logger, config_ssl_verification):

    """Sets the SSL verification config function.

    @param logger: Logging object

    @type config_ssl_verification: callable

    """

    assert self._logger is None

    assert self._config_ssl_verification is None

    self._logger = logger

    self._config_ssl_verification = config_ssl_verification

  def connect(self):

    """Connect to the server specified when the object was created.

    This ensures that SSL certificates are verified.

    """

    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    ctx = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_METHOD)

    ctx.set_options(OpenSSL.SSL.OP_NO_SSLv2)

    if self._config_ssl_verification:

      self._config_ssl_verification(ctx, self._logger)

    ssl = OpenSSL.SSL.Connection(ctx, sock)

    ssl.connect((self.host, self.port))

    self.sock = httplib.FakeSocket(sock, ssl)

class _HTTPSHandler(urllib2.HTTPSHandler):

  def __init__(self, logger, config_ssl_verification):

    """Initializes this class.

    @param logger: Logging object

    @type config_ssl_verification: callable

    @param config_ssl_verification: Function to configure SSL context for

                                    certificate verification

    """

    urllib2.HTTPSHandler.__init__(self)

    self._logger = logger

    self._config_ssl_verification = config_ssl_verification

  def _CreateHttpsConnection(self, *args, **kwargs):

    """Wrapper around L{_HTTPSConnectionOpenSSL} to add SSL verification.

    This wrapper is necessary provide a compatible API to urllib2.

    """

    conn = _HTTPSConnectionOpenSSL(*args, **kwargs)

    conn.Setup(self._logger, self._config_ssl_verification)

    return conn

  def https_open(self, req):

    """Creates HTTPS connection.

    Called by urllib2.

    """

    return self.do_open(self._CreateHttpsConnection, req)

class _RapiRequest(urllib2.Request):

  def __init__(self, method, url, headers, data):

    """Initializes this class.

    """

    urllib2.Request.__init__(self, url, data=data, headers=headers)

    self._method = method

  def get_method(self):

    """Returns the HTTP request method.

    """

    return self._method

class GanetiRapiClient(object):

  """Ganeti RAPI client.

  """

  USER_AGENT = "Ganeti RAPI Client"

  _json_encoder = simplejson.JSONEncoder(sort_keys=True)

  def __init__(self, host, port=GANETI_RAPI_PORT,

               username=None, password=None,

               config_ssl_verification=None, ignore_proxy=False,

               logger=logging):

    """Constructor.

    @type host: string

    @param host: the ganeti cluster master to interact with

    @type port: int

    @param port: the port on which the RAPI is running (default is 5080)

    @type username: string

    @param username: the username to connect with

    @type password: string

    @param password: the password to connect with

    @type config_ssl_verification: callable

    @param config_ssl_verification: Function to configure SSL context for

                                    certificate verification

    @type ignore_proxy: bool

    @param ignore_proxy: Whether to ignore proxy settings

    @param logger: Logging object

    """

    self._host = host

    self._port = port

    self._logger = logger

    self._base_url = "https://%s:%s" % (host, port)

    handlers = [_HTTPSHandler(self._logger, config_ssl_verification)]

    if username is not None:

      pwmgr = urllib2.HTTPPasswordMgrWithDefaultRealm()

      pwmgr.add_password(None, self._base_url, username, password)

      handlers.append(urllib2.HTTPBasicAuthHandler(pwmgr))

    elif password:

      raise Error("Specified password without username")

    if ignore_proxy:

      handlers.append(urllib2.ProxyHandler({}))

    self._http = urllib2.build_opener(*handlers) # pylint: disable-msg=W0142

    self._headers = {

      "Accept": HTTP_APP_JSON,

      "Content-type": HTTP_APP_JSON,

      "User-Agent": self.USER_AGENT,

      }

  @staticmethod

  def _EncodeQuery(query):

    """Encode query values for RAPI URL.

    @type query: list of two-tuples

    @param query: Query arguments

    @rtype: list

    @return: Query list with encoded values

    """

    result = []

    for name, value in query:

      if value is None:

        result.append((name, ""))

      elif isinstance(value, bool):

        # Boolean values must be encoded as 0 or 1

        result.append((name, int(value)))

      elif isinstance(value, (list, tuple, dict)):

        raise ValueError("Invalid query data type %r" % type(value).__name__)

      else:

        result.append((name, value))

    return result

  def _SendRequest(self, method, path, query, content):

    """Sends an HTTP request.

    This constructs a full URL, encodes and decodes HTTP bodies, and

    handles invalid responses in a pythonic way.

    @type method: string

    @param method: HTTP method to use

    @type path: string

    @param path: HTTP URL path

    @type query: list of two-tuples

    @param query: query arguments to pass to urllib.urlencode

    @type content: str or None

    @param content: HTTP body content

    @rtype: str

    @return: JSON-Decoded response

    @raises CertificateError: If an invalid SSL certificate is found

    @raises GanetiApiError: If an invalid response is returned

    """

    assert path.startswith("/")

    if content:

      encoded_content = self._json_encoder.encode(content)

    else:

      encoded_content = None

    # Build URL

    urlparts = [self._base_url, path]

    if query:

      urlparts.append("?")

      urlparts.append(urllib.urlencode(self._EncodeQuery(query)))

    url = "".join(urlparts)

    self._logger.debug("Sending request %s %s to %s:%s"

                       " (headers=%r, content=%r)",

                       method, url, self._host, self._port, self._headers,

                       encoded_content)

    req = _RapiRequest(method, url, self._headers, encoded_content)

    try:

      resp = self._http.open(req)

      encoded_response_content = resp.read()

    except (OpenSSL.SSL.Error, OpenSSL.crypto.Error), err:

      raise CertificateError("SSL issue: %s (%r)" % (err, err))

    except urllib2.HTTPError, err:

      raise GanetiApiError(str(err), code=err.code)

    if encoded_response_content:

      response_content = simplejson.loads(encoded_response_content)

    else:

      response_content = None

    # TODO: Are there other status codes that are valid? (redirect?)

    if resp.code != HTTP_OK:

      if isinstance(response_content, dict):

        msg = ("%s %s: %s" %

               (response_content["code"],

                response_content["message"],

                response_content["explain"]))

      else:

        msg = str(response_content)

      raise GanetiApiError(msg, code=resp.code)

    return response_content

  def GetVersion(self):

    """Gets the Remote API version running on the cluster.

    @rtype: int

    @return: Ganeti Remote API version

    """

    return self._SendRequest(HTTP_GET, "/version", None, None)

  def GetFeatures(self):

    """Gets the list of optional features supported by RAPI server.

    @rtype: list

    @return: List of optional features

    """

    try:

      return self._SendRequest(HTTP_GET, "/%s/features" % GANETI_RAPI_VERSION,

                               None, None)

    except GanetiApiError, err:

      # Older RAPI servers don't support this resource

      if err.code == HTTP_NOT_FOUND:

        return []

      raise

  def GetOperatingSystems(self):

    """Gets the Operating Systems running in the Ganeti cluster.

    @rtype: list of str

    @return: operating systems

    """

    return self._SendRequest(HTTP_GET, "/%s/os" % GANETI_RAPI_VERSION,

                             None, None)

  def GetInfo(self):

    """Gets info about the cluster.

    @rtype: dict

    @return: information about the cluster

    """

    return self._SendRequest(HTTP_GET, "/%s/info" % GANETI_RAPI_VERSION,

                             None, None)

  def GetClusterTags(self):

    """Gets the cluster tags.

    @rtype: list of str

    @return: cluster tags

    """

    return self._SendRequest(HTTP_GET, "/%s/tags" % GANETI_RAPI_VERSION,

                             None, None)

  def AddClusterTags(self, tags, dry_run=False):

    """Adds tags to the cluster.

    @type tags: list of str

    @param tags: tags to add to the cluster

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    @rtype: int

    @return: job id

    """

    query = [("tag", t) for t in tags]

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_PUT, "/%s/tags" % GANETI_RAPI_VERSION,

                             query, None)

  def DeleteClusterTags(self, tags, dry_run=False):

    """Deletes tags from the cluster.

    @type tags: list of str

    @param tags: tags to delete

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = [("tag", t) for t in tags]

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_DELETE, "/%s/tags" % GANETI_RAPI_VERSION,

                             query, None)

  def GetInstances(self, bulk=False):

    """Gets information about instances on the cluster.

    @type bulk: bool

    @param bulk: whether to return all information about all instances

    @rtype: list of dict or list of str

    @return: if bulk is True, info about the instances, else a list of instances

    """

    query = []

    if bulk:

      query.append(("bulk", 1))

    instances = self._SendRequest(HTTP_GET,

                                  "/%s/instances" % GANETI_RAPI_VERSION,

                                  query, None)

    if bulk:

      return instances

    else:

      return [i["id"] for i in instances]

  def GetInstance(self, instance):

    """Gets information about an instance.

    @type instance: str

    @param instance: instance whose info to return

    @rtype: dict

    @return: info about the instance

    """

    return self._SendRequest(HTTP_GET,

                             ("/%s/instances/%s" %

                              (GANETI_RAPI_VERSION, instance)), None, None)

  def GetInstanceInfo(self, instance, static=None):

    """Gets information about an instance.

    @type instance: string

    @param instance: Instance name

    @rtype: string

    @return: Job ID

    """

    if static is not None:

      query = [("static", static)]

    else:

      query = None

    return self._SendRequest(HTTP_GET,

                             ("/%s/instances/%s/info" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def CreateInstance(self, mode, name, disk_template, disks, nics,

                     **kwargs):

    """Creates a new instance.

    More details for parameters can be found in the RAPI documentation.

    @type mode: string

    @param mode: Instance creation mode

    @type name: string

    @param name: Hostname of the instance to create

    @type disk_template: string

    @param disk_template: Disk template for instance (e.g. plain, diskless,

                          file, or drbd)

    @type disks: list of dicts

    @param disks: List of disk definitions

    @type nics: list of dicts

    @param nics: List of NIC definitions

    @type dry_run: bool

    @keyword dry_run: whether to perform a dry run

    @rtype: int

    @return: job id

    """

    query = []

    if kwargs.get("dry_run"):

      query.append(("dry-run", 1))

    if _INST_CREATE_REQV1 in self.GetFeatures():

      # All required fields for request data version 1

      body = {

        _REQ_DATA_VERSION_FIELD: 1,

        "mode": mode,

        "name": name,

        "disk_template": disk_template,

        "disks": disks,

        "nics": nics,

        }

      conflicts = set(kwargs.iterkeys()) & set(body.iterkeys())

      if conflicts:

        raise GanetiApiError("Required fields can not be specified as"

                             " keywords: %s" % ", ".join(conflicts))

      body.update((key, value) for key, value in kwargs.iteritems()

                  if key != "dry_run")

    else:

      # TODO: Implement instance creation request data version 0

      # When implementing version 0, care should be taken to refuse unknown

      # parameters and invalid values. The interface of this function must stay

      # exactly the same for version 0 and 1 (e.g. they aren't allowed to

      # require different data types).

      raise NotImplementedError("Support for instance creation request data"

                                " version 0 is not yet implemented")

    return self._SendRequest(HTTP_POST, "/%s/instances" % GANETI_RAPI_VERSION,

                             query, body)

  def DeleteInstance(self, instance, dry_run=False):

    """Deletes an instance.

    @type instance: str

    @param instance: the instance to delete

    @rtype: int

    @return: job id

    """

    query = []

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_DELETE,

                             ("/%s/instances/%s" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def GetInstanceTags(self, instance):

    """Gets tags for an instance.

    @type instance: str

    @param instance: instance whose tags to return

    @rtype: list of str

    @return: tags for the instance

    """

    return self._SendRequest(HTTP_GET,

                             ("/%s/instances/%s/tags" %

                              (GANETI_RAPI_VERSION, instance)), None, None)

  def AddInstanceTags(self, instance, tags, dry_run=False):

    """Adds tags to an instance.

    @type instance: str

    @param instance: instance to add tags to

    @type tags: list of str

    @param tags: tags to add to the instance

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    @rtype: int

    @return: job id

    """

    query = [("tag", t) for t in tags]

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_PUT,

                             ("/%s/instances/%s/tags" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def DeleteInstanceTags(self, instance, tags, dry_run=False):

    """Deletes tags from an instance.

    @type instance: str

    @param instance: instance to delete tags from

    @type tags: list of str

    @param tags: tags to delete

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = [("tag", t) for t in tags]

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_DELETE,

                             ("/%s/instances/%s/tags" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def RebootInstance(self, instance, reboot_type=None, ignore_secondaries=None,

                     dry_run=False):

    """Reboots an instance.

    @type instance: str

    @param instance: instance to rebot

    @type reboot_type: str

    @param reboot_type: one of: hard, soft, full

    @type ignore_secondaries: bool

    @param ignore_secondaries: if True, ignores errors for the secondary node

        while re-assembling disks (in hard-reboot mode only)

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = []

    if reboot_type:

      query.append(("type", reboot_type))

    if ignore_secondaries is not None:

      query.append(("ignore_secondaries", ignore_secondaries))

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_POST,

                             ("/%s/instances/%s/reboot" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def ShutdownInstance(self, instance, dry_run=False):

    """Shuts down an instance.

    @type instance: str

    @param instance: the instance to shut down

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = []

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_PUT,

                             ("/%s/instances/%s/shutdown" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def StartupInstance(self, instance, dry_run=False):

    """Starts up an instance.

    @type instance: str

    @param instance: the instance to start up

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = []

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_PUT,

                             ("/%s/instances/%s/startup" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def ReinstallInstance(self, instance, os, no_startup=False):

    """Reinstalls an instance.

    @type instance: str

    @param instance: the instance to reinstall

    @type os: str

    @param os: the os to reinstall

    @type no_startup: bool

    @param no_startup: whether to start the instance automatically

    """

    query = [("os", os)]

    if no_startup:

      query.append(("nostartup", 1))

    return self._SendRequest(HTTP_POST,

                             ("/%s/instances/%s/reinstall" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def ReplaceInstanceDisks(self, instance, disks=None, mode=REPLACE_DISK_AUTO,

                           remote_node=None, iallocator=None, dry_run=False):

    """Replaces disks on an instance.

    @type instance: str

    @param instance: instance whose disks to replace

    @type disks: list of ints

    @param disks: Indexes of disks to replace

    @type mode: str

    @param mode: replacement mode to use (defaults to replace_auto)

    @type remote_node: str or None

    @param remote_node: new secondary node to use (for use with

        replace_new_secondary mode)

    @type iallocator: str or None

    @param iallocator: instance allocator plugin to use (for use with

                       replace_auto mode)

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    @rtype: int

    @return: job id

    """

    query = [

      ("mode", mode),

      ]

    if disks:

      query.append(("disks", ",".join(str(idx) for idx in disks)))

    if remote_node:

      query.append(("remote_node", remote_node))

    if iallocator:

      query.append(("iallocator", iallocator))

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_POST,

                             ("/%s/instances/%s/replace-disks" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def PrepareExport(self, instance, mode):

    """Prepares an instance for an export.

    @type instance: string

    @param instance: Instance name

    @type mode: string

    @param mode: Export mode

    @rtype: string

    @return: Job ID

    """

    query = [("mode", mode)]

    return self._SendRequest(HTTP_PUT,

                             ("/%s/instances/%s/prepare-export" %

                              (GANETI_RAPI_VERSION, instance)), query, None)

  def ExportInstance(self, instance, mode, destination, shutdown=None,

                     remove_instance=None,

                     x509_key_name=None, destination_x509_ca=None):

    """Exports an instance.

    @type instance: string

    @param instance: Instance name

    @type mode: string

    @param mode: Export mode

    @rtype: string

    @return: Job ID

    """

    body = {

      "destination": destination,

      "mode": mode,

      }

    if shutdown is not None:

      body["shutdown"] = shutdown

    if remove_instance is not None:

      body["remove_instance"] = remove_instance

    if x509_key_name is not None:

      body["x509_key_name"] = x509_key_name

    if destination_x509_ca is not None:

      body["destination_x509_ca"] = destination_x509_ca

    return self._SendRequest(HTTP_PUT,

                             ("/%s/instances/%s/export" %

                              (GANETI_RAPI_VERSION, instance)), None, body)

  def GetJobs(self):

    """Gets all jobs for the cluster.

    @rtype: list of int

    @return: job ids for the cluster

    """

    return [int(j["id"])

            for j in self._SendRequest(HTTP_GET,

                                       "/%s/jobs" % GANETI_RAPI_VERSION,

                                       None, None)]

  def GetJobStatus(self, job_id):

    """Gets the status of a job.

    @type job_id: int

    @param job_id: job id whose status to query

    @rtype: dict

    @return: job status

    """

    return self._SendRequest(HTTP_GET,

                             "/%s/jobs/%s" % (GANETI_RAPI_VERSION, job_id),

                             None, None)

  def WaitForJobChange(self, job_id, fields, prev_job_info, prev_log_serial):

    """Waits for job changes.

    @type job_id: int

    @param job_id: Job ID for which to wait

    """

    body = {

      "fields": fields,

      "previous_job_info": prev_job_info,

      "previous_log_serial": prev_log_serial,

      }

    return self._SendRequest(HTTP_GET,

                             "/%s/jobs/%s/wait" % (GANETI_RAPI_VERSION, job_id),

                             None, body)

  def CancelJob(self, job_id, dry_run=False):

    """Cancels a job.

    @type job_id: int

    @param job_id: id of the job to delete

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    """

    query = []

    if dry_run:

      query.append(("dry-run", 1))

    return self._SendRequest(HTTP_DELETE,

                             "/%s/jobs/%s" % (GANETI_RAPI_VERSION, job_id),

                             query, None)

  def GetNodes(self, bulk=False):

    """Gets all nodes in the cluster.

    @type bulk: bool

    @param bulk: whether to return all information about all instances

    @rtype: list of dict or str

    @return: if bulk is true, info about nodes in the cluster,

        else list of nodes in the cluster

    """

    query = []

    if bulk:

      query.append(("bulk", 1))

    nodes = self._SendRequest(HTTP_GET, "/%s/nodes" % GANETI_RAPI_VERSION,

                              query, None)

    if bulk:

      return nodes

    else:

      return [n["id"] for n in nodes]

  def GetNode(self, node):

    """Gets information about a node.

    @type node: str

    @param node: node whose info to return

    @rtype: dict

    @return: info about the node

    """

    return self._SendRequest(HTTP_GET,

                             "/%s/nodes/%s" % (GANETI_RAPI_VERSION, node),

                             None, None)

  def EvacuateNode(self, node, iallocator=None, remote_node=None,

                   dry_run=False):

    """Evacuates instances from a Ganeti node.

    @type node: str

    @param node: node to evacuate

    @type iallocator: str or None

    @param iallocator: instance allocator to use

    @type remote_node: str

    @param remote_node: node to evaucate to

    @type dry_run: bool

    @param dry_run: whether to perform a dry run

    @rtype: int

    @return: job id

    @raises GanetiApiError: if an iallocator and remote_node are both specified

    """

    if iallocator and remote_node:

      raise GanetiApiError("Only one of iallocator or remote_node can be used")