Synnefo

# Copyright 2011 GRNET S.A. All rights reserved.

#

# Redistribution and use in source and binary forms, with or

# without modification, are permitted provided that the following

# conditions are met:

#

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

#

#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

#

# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

# POSSIBILITY OF SUCH DAMAGE.

#

# The views and conclusions contained in the software and

# documentation are those of the authors and should not be

# interpreted as representing official policies, either expressed

# or implied, of GRNET S.A.

import json

from django.conf import settings

from django.db import transaction

from datetime import datetime

from synnefo.db.models import (Backend, VirtualMachine, Network,

                               BackendNetwork, BACKEND_STATUSES,

                               pooled_rapi_client, VirtualMachineDiagnostic)

from synnefo.logic import utils

from synnefo import quotas

from synnefo.api.util import release_resource

from synnefo.util.mac2eui64 import mac2eui64

from logging import getLogger

log = getLogger(__name__)

_firewall_tags = {

    'ENABLED': settings.GANETI_FIREWALL_ENABLED_TAG,

    'DISABLED': settings.GANETI_FIREWALL_DISABLED_TAG,

    'PROTECTED': settings.GANETI_FIREWALL_PROTECTED_TAG}

_reverse_tags = dict((v.split(':')[3], k) for k, v in _firewall_tags.items())

@transaction.commit_on_success

def process_op_status(vm, etime, jobid, opcode, status, logmsg, nics=None):

    """Process a job progress notification from the backend

    Process an incoming message from the backend (currently Ganeti).

    Job notifications with a terminating status (sucess, error, or canceled),

    also update the operating state of the VM.

    """

    # See #1492, #1031, #1111 why this line has been removed

    #if (opcode not in [x[0] for x in VirtualMachine.BACKEND_OPCODES] or

    if status not in [x[0] for x in BACKEND_STATUSES]:

        raise VirtualMachine.InvalidBackendMsgError(opcode, status)

    vm.backendjobid = jobid

    vm.backendjobstatus = status

    vm.backendopcode = opcode

    vm.backendlogmsg = logmsg

    # Notifications of success change the operating state

    state_for_success = VirtualMachine.OPER_STATE_FROM_OPCODE.get(opcode, None)

    if status == 'success' and state_for_success is not None:

        vm.operstate = state_for_success

    # Update the NICs of the VM

    if status == "success" and nics is not None:

        _process_net_status(vm, etime, nics)

    # Special case: if OP_INSTANCE_CREATE fails --> ERROR

    if opcode == 'OP_INSTANCE_CREATE' and status in ('canceled', 'error'):

        vm.operstate = 'ERROR'

        vm.backendtime = etime

    elif opcode == 'OP_INSTANCE_REMOVE':

        # Set the deleted flag explicitly, cater for admin-initiated removals

        # Special case: OP_INSTANCE_REMOVE fails for machines in ERROR,

        # when no instance exists at the Ganeti backend.

        # See ticket #799 for all the details.

        #

        if status == 'success' or (status == 'error' and

                                   vm.operstate == 'ERROR'):

            _process_net_status(vm, etime, nics=[])

            vm.deleted = True

            vm.operstate = state_for_success

            vm.backendtime = etime

            # Issue and accept commission to Quotaholder

            quotas.issue_and_accept_commission(vm, delete=True)

    # Update backendtime only for jobs that have been successfully completed,

    # since only these jobs update the state of the VM. Else a "race condition"

    # may occur when a successful job (e.g. OP_INSTANCE_REMOVE) completes

    # before an error job and messages arrive in reversed order.

    if status == 'success':

        vm.backendtime = etime

    vm.save()

@transaction.commit_on_success

def process_net_status(vm, etime, nics):

    """Wrap _process_net_status inside transaction."""

    _process_net_status(vm, etime, nics)

def _process_net_status(vm, etime, nics):

    """Process a net status notification from the backend

    Process an incoming message from the Ganeti backend,

    detailing the NIC configuration of a VM instance.

    Update the state of the VM in the DB accordingly.

    """

    ganeti_nics = process_ganeti_nics(nics)

    if not nics_changed(vm.nics.order_by('index'), ganeti_nics):

        log.debug("NICs for VM %s have not changed", vm)

        return

    # Get X-Lock on backend before getting X-Lock on network IP pools, to

    # guarantee that no deadlock will occur with Backend allocator.

    Backend.objects.select_for_update().get(id=vm.backend_id)

    release_instance_nics(vm)

    for nic in ganeti_nics:

        ipv4 = nic.get('ipv4', '')

        net = nic['network']

        if ipv4:

            net.reserve_address(ipv4)

        nic['dirty'] = False

        vm.nics.create(**nic)

        # Dummy save the network, because UI uses changed-since for VMs

        # and Networks in order to show the VM NICs

        net.save()

    vm.backendtime = etime

    vm.save()

def process_ganeti_nics(ganeti_nics):

    """Process NIC dict from ganeti hooks."""

    new_nics = []

    for i, new_nic in enumerate(ganeti_nics):

        network = new_nic.get('network', '')

        n = str(network)

        pk = utils.id_from_network_name(n)

        net = Network.objects.get(pk=pk)

        # Get the new nic info

        mac = new_nic.get('mac', '')

        ipv4 = new_nic.get('ip', '')

        if net.subnet6:

            ipv6 = mac2eui64(mac, net.subnet6)

        else:

            ipv6 = ''

        firewall = new_nic.get('firewall', '')

        firewall_profile = _reverse_tags.get(firewall, '')

        if not firewall_profile and net.public:

            firewall_profile = settings.DEFAULT_FIREWALL_PROFILE

        nic = {

            'index': i,

            'network': net,

            'mac': mac,

            'ipv4': ipv4,

            'ipv6': ipv6,

            'firewall_profile': firewall_profile,

            'state': 'ACTIVE'}

        new_nics.append(nic)

    return new_nics

def nics_changed(old_nics, new_nics):

    """Return True if NICs have changed in any way."""

    if len(old_nics) != len(new_nics):

        return True

    fields = ["ipv4", "ipv6", "mac", "firewall_profile", "index", "network"]

    for old_nic, new_nic in zip(old_nics, new_nics):

        for field in fields:

            if getattr(old_nic, field) != new_nic[field]:

                return True

    return False

def release_instance_nics(vm):

    for nic in vm.nics.all():

        net = nic.network

        if nic.ipv4:

            net.release_address(nic.ipv4)

        nic.delete()

        net.save()

@transaction.commit_on_success

def process_network_status(back_network, etime, jobid, opcode, status, logmsg):

    if status not in [x[0] for x in BACKEND_STATUSES]:

        raise Network.InvalidBackendMsgError(opcode, status)

    back_network.backendjobid = jobid

    back_network.backendjobstatus = status

    back_network.backendopcode = opcode

    back_network.backendlogmsg = logmsg

    # Notifications of success change the operating state

    state_for_success = BackendNetwork.OPER_STATE_FROM_OPCODE.get(opcode, None)

    if status == 'success' and state_for_success is not None:

        back_network.operstate = state_for_success

    if status in ('canceled', 'error') and opcode == 'OP_NETWORK_ADD':

        back_network.operstate = 'ERROR'

        back_network.backendtime = etime

    if opcode == 'OP_NETWORK_REMOVE':

        if status == 'success' or (status == 'error' and

                                   back_network.operstate == 'ERROR'):

            back_network.operstate = state_for_success

            back_network.deleted = True

            back_network.backendtime = etime

    if status == 'success':

        back_network.backendtime = etime

    back_network.save()

    # Also you must update the state of the Network!!

    update_network_state(back_network.network)

def update_network_state(network):

    """Update the state of a Network based on BackendNetwork states.

    Update the state of a Network based on the operstate of the networks in the

    backends that network exists.

    The state of the network is:

    * ACTIVE: If it is 'ACTIVE' in at least one backend.

    * DELETED: If it is is 'DELETED' in all backends that have been created.

    This function also releases the resources (MAC prefix or Bridge) and the

    quotas for the network.

    """

    if network.deleted:

        # Network has already been deleted. Just assert that state is also

        # DELETED

        if not network.state == "DELETED":

            network.state = "DELETED"

            network.save()

        return

    backend_states = [s.operstate for s in network.backend_networks.all()]

    if not backend_states and network.action != "DESTROY":

        if network.state != "ACTIVE":

            network.state = "ACTIVE"

            network.save()

            return

    # Network is deleted when all BackendNetworks go to "DELETED" operstate

    deleted = reduce(lambda x, y: x == y and "DELETED", backend_states,

                     "DELETED")

    # Release the resources on the deletion of the Network

    if deleted:

        log.info("Network %r deleted. Releasing link %r mac_prefix %r",

                 network.id, network.mac_prefix, network.link)

        network.deleted = True

        network.state = "DELETED"

        if network.mac_prefix:

            if network.FLAVORS[network.flavor]["mac_prefix"] == "pool":

                release_resource(res_type="mac_prefix",

                                 value=network.mac_prefix)

        if network.link:

            if network.FLAVORS[network.flavor]["link"] == "pool":

                release_resource(res_type="bridge", value=network.link)

        # Issue commission

        if network.userid:

            quotas.issue_and_accept_commission(network, delete=True)

        elif not network.public:

            log.warning("Network %s does not have an owner!", network.id)

    network.save()

@transaction.commit_on_success

def process_network_modify(back_network, etime, jobid, opcode, status,

                           add_reserved_ips, remove_reserved_ips):

    assert (opcode == "OP_NETWORK_SET_PARAMS")

    if status not in [x[0] for x in BACKEND_STATUSES]:

        raise Network.InvalidBackendMsgError(opcode, status)

    back_network.backendjobid = jobid

    back_network.backendjobstatus = status

    back_network.opcode = opcode

    if add_reserved_ips or remove_reserved_ips:

        net = back_network.network

        pool = net.get_pool()

        if add_reserved_ips:

            for ip in add_reserved_ips:

                pool.reserve(ip, external=True)

        if remove_reserved_ips:

            for ip in remove_reserved_ips:

                pool.put(ip, external=True)

        pool.save()

    if status == 'success':

        back_network.backendtime = etime

    back_network.save()

@transaction.commit_on_success

def process_create_progress(vm, etime, progress):

    percentage = int(progress)

    # The percentage may exceed 100%, due to the way

    # snf-image:copy-progress tracks bytes read by image handling processes

    percentage = 100 if percentage > 100 else percentage

    if percentage < 0:

        raise ValueError("Percentage cannot be negative")

    # FIXME: log a warning here, see #1033

#   if last_update > percentage:

#       raise ValueError("Build percentage should increase monotonically " \

#                        "(old = %d, new = %d)" % (last_update, percentage))

    # This assumes that no message of type 'ganeti-create-progress' is going to

    # arrive once OP_INSTANCE_CREATE has succeeded for a Ganeti instance and

    # the instance is STARTED.  What if the two messages are processed by two

    # separate dispatcher threads, and the 'ganeti-op-status' message for

    # successful creation gets processed before the 'ganeti-create-progress'

    # message? [vkoukis]

    #

    #if not vm.operstate == 'BUILD':

    #    raise VirtualMachine.IllegalState("VM is not in building state")

    vm.buildpercentage = percentage

    vm.backendtime = etime

    vm.save()

def create_instance_diagnostic(vm, message, source, level="DEBUG", etime=None,

                               details=None):

    """

    Create virtual machine instance diagnostic entry.

    :param vm: VirtualMachine instance to create diagnostic for.

    :param message: Diagnostic message.

    :param source: Diagnostic source identifier (e.g. image-helper).

    :param level: Diagnostic level (`DEBUG`, `INFO`, `WARNING`, `ERROR`).

    :param etime: The time the message occured (if available).

    :param details: Additional details or debug information.

    """

    VirtualMachineDiagnostic.objects.create_for_vm(vm, level, source=source,

                                                   source_date=etime,

                                                   message=message,

                                                   details=details)

def create_instance(vm, public_nic, flavor, image):

    """`image` is a dictionary which should contain the keys:

            'backend_id', 'format' and 'metadata'

        metadata value should be a dictionary.

    """

    # Handle arguments to CreateInstance() as a dictionary,

    # initialize it based on a deployment-specific value.

    # This enables the administrator to override deployment-specific

    # arguments, such as the disk template to use, name of os provider

    # and hypervisor-specific parameters at will (see Synnefo #785, #835).

    #

    kw = vm.backend.get_create_params()

    kw['mode'] = 'create'

    kw['name'] = vm.backend_vm_id

    # Defined in settings.GANETI_CREATEINSTANCE_KWARGS

    kw['disk_template'] = flavor.disk_template

    kw['disks'] = [{"size": flavor.disk * 1024}]

    provider = flavor.disk_provider

    if provider:

        kw['disks'][0]['provider'] = provider

        kw['disks'][0]['origin'] = flavor.disk_origin

    kw['nics'] = [public_nic]

    if vm.backend.use_hotplug():

        kw['hotplug'] = True

    # Defined in settings.GANETI_CREATEINSTANCE_KWARGS

    # kw['os'] = settings.GANETI_OS_PROVIDER

    kw['ip_check'] = False

    kw['name_check'] = False

    # Do not specific a node explicitly, have

    # Ganeti use an iallocator instead

    #kw['pnode'] = rapi.GetNodes()[0]

    kw['dry_run'] = settings.TEST

    kw['beparams'] = {

        'auto_balance': True,

        'vcpus': flavor.cpu,

        'memory': flavor.ram}

    kw['osparams'] = {

        'config_url': vm.config_url,

        # Store image id and format to Ganeti

        'img_id': image['backend_id'],

        'img_format': image['format']}

    # Defined in settings.GANETI_CREATEINSTANCE_KWARGS

    # kw['hvparams'] = dict(serial_console=False)

    log.debug("Creating instance %s", utils.hide_pass(kw))

    with pooled_rapi_client(vm) as client:

        return client.CreateInstance(**kw)

def delete_instance(vm):

    with pooled_rapi_client(vm) as client:

        return client.DeleteInstance(vm.backend_vm_id, dry_run=settings.TEST)

def reboot_instance(vm, reboot_type):

    assert reboot_type in ('soft', 'hard')

    with pooled_rapi_client(vm) as client:

        return client.RebootInstance(vm.backend_vm_id, reboot_type,

                                     dry_run=settings.TEST)

def startup_instance(vm):

    with pooled_rapi_client(vm) as client:

        return client.StartupInstance(vm.backend_vm_id, dry_run=settings.TEST)

def shutdown_instance(vm):

    with pooled_rapi_client(vm) as client:

        return client.ShutdownInstance(vm.backend_vm_id, dry_run=settings.TEST)

def get_instance_console(vm):

    # RAPI GetInstanceConsole() returns endpoints to the vnc_bind_address,

    # which is a cluster-wide setting, either 0.0.0.0 or 127.0.0.1, and pretty

    # useless (see #783).

    #

    # Until this is fixed on the Ganeti side, construct a console info reply

    # directly.

    #

    # WARNING: This assumes that VNC runs on port network_port on

    #          the instance's primary node, and is probably

    #          hypervisor-specific.

    #

    log.debug("Getting console for vm %s", vm)

    console = {}

    console['kind'] = 'vnc'

    with pooled_rapi_client(vm) as client:

        i = client.GetInstance(vm.backend_vm_id)

    if vm.backend.hypervisor == "kvm" and i['hvparams']['serial_console']:

        raise Exception("hv parameter serial_console cannot be true")

    console['host'] = i['pnode']

    console['port'] = i['network_port']

    return console

def get_instance_info(vm):

    with pooled_rapi_client(vm) as client:

        return client.GetInstanceInfo(vm.backend_vm_id)

def create_network(network, backend, connect=True):

    """Create a network in a Ganeti backend"""

    log.debug("Creating network %s in backend %s", network, backend)

    job_id = _create_network(network, backend)

    if connect:

        job_ids = connect_network(network, backend, depends=[job_id])

        return job_ids

    else:

        return [job_id]

def _create_network(network, backend):

    """Create a network."""

    network_type = network.public and 'public' or 'private'

    tags = network.backend_tag

    if network.dhcp:

        tags.append('nfdhcpd')

    if network.public:

        conflicts_check = True

    else:

        conflicts_check = False

    try:

        bn = BackendNetwork.objects.get(network=network, backend=backend)

        mac_prefix = bn.mac_prefix

    except BackendNetwork.DoesNotExist:

        raise Exception("BackendNetwork for network '%s' in backend '%s'"

                        " does not exist" % (network.id, backend.id))

    with pooled_rapi_client(backend) as client:

        return client.CreateNetwork(network_name=network.backend_id,

                                    network=network.subnet,

                                    network6=network.subnet6,

                                    gateway=network.gateway,

                                    gateway6=network.gateway6,

                                    network_type=network_type,

                                    mac_prefix=mac_prefix,

                                    conflicts_check=conflicts_check,

                                    tags=tags)

def connect_network(network, backend, depends=[], group=None):

    """Connect a network to nodegroups."""

    log.debug("Connecting network %s to backend %s", network, backend)

    if network.public:

        conflicts_check = True

    else:

        conflicts_check = False

    depends = [[job, ["success", "error", "canceled"]] for job in depends]

    with pooled_rapi_client(backend) as client:

        groups = [group] if group is not None else client.GetGroups()

        job_ids = []

        for group in groups:

            job_id = client.ConnectNetwork(network.backend_id, group,

                                           network.mode, network.link,

                                           conflicts_check,

                                           depends=depends)

            job_ids.append(job_id)

    return job_ids

def delete_network(network, backend, disconnect=True):

    log.debug("Deleting network %s from backend %s", network, backend)

    depends = []

    if disconnect:

        depends = disconnect_network(network, backend)

    _delete_network(network, backend, depends=depends)

def _delete_network(network, backend, depends=[]):

    depends = [[job, ["success", "error", "canceled"]] for job in depends]

    with pooled_rapi_client(backend) as client:

        return client.DeleteNetwork(network.backend_id, depends)

def disconnect_network(network, backend, group=None):

    log.debug("Disconnecting network %s to backend %s", network, backend)

    with pooled_rapi_client(backend) as client:

        groups = [group] if group is not None else client.GetGroups()

        job_ids = []

        for group in groups:

            job_id = client.DisconnectNetwork(network.backend_id, group)

            job_ids.append(job_id)

    return job_ids

def connect_to_network(vm, network, address=None):

    backend = vm.backend

    network = Network.objects.select_for_update().get(id=network.id)

    bnet, created = BackendNetwork.objects.get_or_create(backend=backend,

                                                         network=network)

    depend_jobs = []

    if bnet.operstate != "ACTIVE":

        depend_jobs = create_network(network, backend, connect=True)

    depends = [[job, ["success", "error", "canceled"]] for job in depend_jobs]

    nic = {'ip': address, 'network': network.backend_id}

    log.debug("Connecting vm %s to network %s(%s)", vm, network, address)

    with pooled_rapi_client(vm) as client:

        return client.ModifyInstance(vm.backend_vm_id, nics=[('add',  nic)],

                                     hotplug=vm.backend.use_hotplug(),

                                     depends=depends,

                                     dry_run=settings.TEST)

def disconnect_from_network(vm, nic):

    op = [('remove', nic.index, {})]

    log.debug("Removing nic of VM %s, with index %s", vm, str(nic.index))

    with pooled_rapi_client(vm) as client:

        return client.ModifyInstance(vm.backend_vm_id, nics=op,

                                     hotplug=vm.backend.use_hotplug(),

                                     dry_run=settings.TEST)

def set_firewall_profile(vm, profile):

    try:

        tag = _firewall_tags[profile]

    except KeyError:

        raise ValueError("Unsopported Firewall Profile: %s" % profile)

    log.debug("Setting tag of VM %s to %s", vm, profile)

    with pooled_rapi_client(vm) as client:

        # Delete all firewall tags

        for t in _firewall_tags.values():

            client.DeleteInstanceTags(vm.backend_vm_id, [t],

                                      dry_run=settings.TEST)

        client.AddInstanceTags(vm.backend_vm_id, [tag], dry_run=settings.TEST)

        # XXX NOP ModifyInstance call to force process_net_status to run

        # on the dispatcher

        os_name = settings.GANETI_CREATEINSTANCE_KWARGS['os']

        client.ModifyInstance(vm.backend_vm_id,

                              os_name=os_name)

def get_ganeti_instances(backend=None, bulk=False):

    instances = []

    for backend in get_backends(backend):

        with pooled_rapi_client(backend) as client:

            instances.append(client.GetInstances(bulk=bulk))

    return reduce(list.__add__, instances, [])

def get_ganeti_nodes(backend=None, bulk=False):

    nodes = []

    for backend in get_backends(backend):

        with pooled_rapi_client(backend) as client:

            nodes.append(client.GetNodes(bulk=bulk))

    return reduce(list.__add__, nodes, [])

def get_ganeti_jobs(backend=None, bulk=False):

    jobs = []

    for backend in get_backends(backend):

        with pooled_rapi_client(backend) as client:

            jobs.append(client.GetJobs(bulk=bulk))

    return reduce(list.__add__, jobs, [])

##

##

##

def get_backends(backend=None):

    if backend:

        if backend.offline:

            return []

        return [backend]

    return Backend.objects.filter(offline=False)

def get_physical_resources(backend):

    """ Get the physical resources of a backend.

    Get the resources of a backend as reported by the backend (not the db).

    """

    nodes = get_ganeti_nodes(backend, bulk=True)

    attr = ['mfree', 'mtotal', 'dfree', 'dtotal', 'pinst_cnt', 'ctotal']

    res = {}

    for a in attr:

        res[a] = 0

    for n in nodes:

        # Filter out drained, offline and not vm_capable nodes since they will

        # not take part in the vm allocation process

        can_host_vms = n['vm_capable'] and not (n['drained'] or n['offline'])

        if can_host_vms and n['cnodes']:

            for a in attr:

                res[a] += int(n[a])

    return res

def update_resources(backend, resources=None):

    """ Update the state of the backend resources in db.

    """

    if not resources:

        resources = get_physical_resources(backend)

    backend.mfree = resources['mfree']

    backend.mtotal = resources['mtotal']

    backend.dfree = resources['dfree']

    backend.dtotal = resources['dtotal']

    backend.pinst_cnt = resources['pinst_cnt']

    backend.ctotal = resources['ctotal']

    backend.updated = datetime.now()

    backend.save()

def get_memory_from_instances(backend):

    """ Get the memory that is used from instances.

    Get the used memory of a backend. Note: This is different for

    the real memory used, due to kvm's memory de-duplication.

    """

    with pooled_rapi_client(backend) as client:

        instances = client.GetInstances(bulk=True)

    mem = 0

    for i in instances:

        mem += i['oper_ram']

    return mem

##

## Synchronized operations for reconciliation

##

def create_network_synced(network, backend):

    result = _create_network_synced(network, backend)

    if result[0] != 'success':

        return result

    result = connect_network_synced(network, backend)

    return result

def _create_network_synced(network, backend):

    with pooled_rapi_client(backend) as client:

        job = _create_network(network, backend)

        result = wait_for_job(client, job)

    return result

def connect_network_synced(network, backend):

    with pooled_rapi_client(backend) as client:

        for group in client.GetGroups():

            job = client.ConnectNetwork(network.backend_id, group,

                                        network.mode, network.link)

            result = wait_for_job(client, job)

            if result[0] != 'success':

                return result

    return result

def wait_for_job(client, jobid):

    result = client.WaitForJobChange(jobid, ['status', 'opresult'], None, None)

    status = result['job_info'][0]

    while status not in ['success', 'error', 'cancel']:

        result = client.WaitForJobChange(jobid, ['status', 'opresult'],

                                         [result], None)

        status = result['job_info'][0]

    if status == 'success':

        return (status, None)

    else:

        error = result['job_info'][1]

        return (status, error)