# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.
"""
Drivers for volumes.
"""

import time

from oslo.config import cfg

from cinder import exception
from cinder.i18n import _, _LE
from cinder.image import image_utils
from cinder.openstack.common import excutils
from cinder.openstack.common import fileutils
from cinder.openstack.common import log as logging
from cinder.openstack.common import processutils
from cinder import utils
from cinder.volume import iscsi
from cinder.volume import rpcapi as volume_rpcapi
from cinder.volume import utils as volume_utils

LOG = logging.getLogger(__name__)

volume_opts = [
    cfg.IntOpt('num_shell_tries',
               default=3,
               help='Number of times to attempt to run flakey shell commands'),
    cfg.IntOpt('reserved_percentage',
               default=0,
               help='The percentage of backend capacity is reserved'),
    cfg.IntOpt('iscsi_num_targets',
               default=100,
               help='The maximum number of iSCSI target IDs per host'),
    cfg.StrOpt('iscsi_target_prefix',
               default='iqn.2010-10.org.openstack:',
               help='Prefix for iSCSI volumes'),
    cfg.StrOpt('iscsi_ip_address',
               default='$my_ip',
               help='The IP address that the iSCSI daemon is listening on'),
    cfg.IntOpt('iscsi_port',
               default=3260,
               help='The port that the iSCSI daemon is listening on'),
    cfg.IntOpt('num_volume_device_scan_tries',
               deprecated_name='num_iscsi_scan_tries',
               default=3,
               help='The maximum number of times to rescan targets'
                    ' to find volume'),
    cfg.StrOpt('volume_backend_name',
               default=None,
               help='The backend name for a given driver implementation'),
    cfg.BoolOpt('use_multipath_for_image_xfer',
                default=False,
                help='Do we attach/detach volumes in cinder using multipath '
                     'for volume to image and image to volume transfers?'),
    cfg.StrOpt('volume_clear',
               default='zero',
               help='Method used to wipe old volumes (valid options are: '
                    'none, zero, shred)'),
    cfg.IntOpt('volume_clear_size',
               default=0,
               help='Size in MiB to wipe at start of old volumes. 0 => all'),
    cfg.StrOpt('volume_clear_ionice',
               default=None,
               help='The flag to pass to ionice to alter the i/o priority '
                    'of the process used to zero a volume after deletion, '
                    'for example "-c3" for idle only priority.'),
    cfg.StrOpt('iscsi_helper',
               default='tgtadm',
               help='iSCSI target user-land tool to use. tgtadm is default, '
                    'use lioadm for LIO iSCSI support, iseradm for the ISER '
                    'protocol, or fake for testing.'),
    cfg.StrOpt('volumes_dir',
               default='$state_path/volumes',
               help='Volume configuration file storage '
               'directory'),
    cfg.StrOpt('iet_conf',
               default='/etc/iet/ietd.conf',
               help='IET configuration file'),
    cfg.StrOpt('lio_initiator_iqns',
               default='',
               help=('Comma-separated list of initiator IQNs '
                     'allowed to connect to the '
                     'iSCSI target. (From Nova compute nodes.)')),
    cfg.StrOpt('iscsi_iotype',
               default='fileio',
               help=('Sets the behavior of the iSCSI target '
                     'to either perform blockio or fileio '
                     'optionally, auto can be set and Cinder '
                     'will autodetect type of backing device')),
    cfg.StrOpt('volume_dd_blocksize',
               default='1M',
               help='The default block size used when copying/clearing '
                    'volumes'),
    cfg.StrOpt('volume_copy_blkio_cgroup_name',
               default='cinder-volume-copy',
               help='The blkio cgroup name to be used to limit bandwidth '
                    'of volume copy'),
    cfg.IntOpt('volume_copy_bps_limit',
               default=0,
               help='The upper limit of bandwidth of volume copy. '
                    '0 => unlimited'),
    cfg.StrOpt('iscsi_write_cache',
               default='on',
               help='Sets the behavior of the iSCSI target to either '
                    'perform write-back(on) or write-through(off). '
                    'This parameter is valid if iscsi_helper is set '
                    'to tgtadm or iseradm.'),
    cfg.StrOpt('driver_client_cert_key',
               default=None,
               help='The path to the client certificate key for verification, '
                    'if the driver supports it.'),
    cfg.StrOpt('driver_client_cert',
               default=None,
               help='The path to the client certificate for verification, '
                    'if the driver supports it.'),
]

# for backward compatibility
iser_opts = [
    cfg.IntOpt('num_iser_scan_tries',
               default=3,
               help='The maximum number of times to rescan iSER target'
                    'to find volume'),
    cfg.IntOpt('iser_num_targets',
               default=100,
               help='The maximum number of iSER target IDs per host'),
    cfg.StrOpt('iser_target_prefix',
               default='iqn.2010-10.org.iser.openstack:',
               help='Prefix for iSER volumes'),
    cfg.StrOpt('iser_ip_address',
               default='$my_ip',
               help='The IP address that the iSER daemon is listening on'),
    cfg.IntOpt('iser_port',
               default=3260,
               help='The port that the iSER daemon is listening on'),
    cfg.StrOpt('iser_helper',
               default='tgtadm',
               help='The name of the iSER target user-land tool to use'),
]


CONF = cfg.CONF
CONF.register_opts(volume_opts)
CONF.register_opts(iser_opts)


class VolumeDriver(object):
    """Executes commands relating to Volumes.

       Base Driver for Cinder Volume Control Path,
       This includes supported/required implementation
       for API calls.  Also provides *generic* implementation
       of core features like cloning, copy_image_to_volume etc,
       this way drivers that inherit from this base class and
       don't offer their own impl can fall back on a general
       solution here.

       Key thing to keep in mind with this driver is that it's
       intended that these drivers ONLY implement Control Path
       details (create, delete, extend...), while transport or
       data path related implementation should be a *member object*
       that we call a connector.  The point here is that for example
       don't allow the LVM driver to implement iSCSI methods, instead
       call whatever connector it has configured via conf file
       (iSCSI{LIO, TGT, IET}, FC, etc).

       In the base class and for example the LVM driver we do this via a has-a
       relationship and just provide an interface to the specific connector
       methods.  How you do this in your own driver is of course up to you.
    """

    VERSION = "N/A"

    def __init__(self, execute=utils.execute, *args, **kwargs):
        # NOTE(vish): db is set by Manager
        self.db = kwargs.get('db')
        self.host = kwargs.get('host')
        self.configuration = kwargs.get('configuration', None)

        if self.configuration:
            self.configuration.append_config_values(volume_opts)
            self.configuration.append_config_values(iser_opts)
        self.set_execute(execute)
        self._stats = {}

        self.pools = []

        # set True by manager after successful check_for_setup
        self._initialized = False

    def _is_non_recoverable(self, err, non_recoverable_list):
        for item in non_recoverable_list:
            if item in err:
                return True

        return False

    def _try_execute(self, *command, **kwargs):
        # NOTE(vish): Volume commands can partially fail due to timing, but
        #             running them a second time on failure will usually
        #             recover nicely.

        non_recoverable = kwargs.pop('no_retry_list', [])

        tries = 0
        while True:
            try:
                self._execute(*command, **kwargs)
                return True
            except processutils.ProcessExecutionError as ex:
                tries = tries + 1

                if tries >= self.configuration.num_shell_tries or\
                        self._is_non_recoverable(ex.stderr, non_recoverable):
                    raise

                LOG.exception(_LE("Recovering from a failed execute.  "
                                  "Try number %s"), tries)
                time.sleep(tries ** 2)

    def _detach_volume(self, context, attach_info, volume, properties,
                       force=False, remote=False):
        """Disconnect the volume from the host."""
        # Use Brick's code to do attach/detach
        connector = attach_info['connector']
        connector.disconnect_volume(attach_info['conn']['data'],
                                    attach_info['device'])

        if remote:
            # Call remote manager's terminate_connection which includes
            # driver's terminate_connection and remove export
            rpcapi = volume_rpcapi.VolumeAPI()
            rpcapi.terminate_connection(context, volume, properties,
                                        force=force)
        else:
            # Call local driver's terminate_connection and remove export.
            # NOTE(avishay) This is copied from the manager's code - need to
            # clean this up in the future.
            try:
                self.terminate_connection(volume, properties, force=force)
            except Exception as err:
                err_msg = (_('Unable to terminate volume connection: %(err)s')
                           % {'err': err})
                LOG.error(err_msg)
                raise exception.VolumeBackendAPIException(data=err_msg)

            try:
                LOG.debug(("volume %s: removing export"), volume['id'])
                self.remove_export(context, volume)
            except Exception as ex:
                LOG.exception(_LE("Error detaching volume %(volume)s, "
                                  "due to remove export failure."),
                              {"volume": volume['id']})
                raise exception.RemoveExportException(volume=volume['id'],
                                                      reason=ex)

    def set_execute(self, execute):
        self._execute = execute

    def set_initialized(self):
        self._initialized = True

    @property
    def initialized(self):
        return self._initialized

    def get_version(self):
        """Get the current version of this driver."""
        return self.VERSION

    def check_for_setup_error(self):
        raise NotImplementedError()

    def create_volume(self, volume):
        """Creates a volume. Can optionally return a Dictionary of
        changes to the volume object to be persisted.

        If volume_type extra specs includes
        'capabilities:replication <is> True' the driver
        needs to create a volume replica (secondary), and setup replication
        between the newly created volume and the secondary volume.
        Returned dictionary should include:
            volume['replication_status'] = 'copying'
            volume['replication_extended_status'] = driver specific value
            volume['driver_data'] = driver specific value

        """
        raise NotImplementedError()

    def create_volume_from_snapshot(self, volume, snapshot):
        """Creates a volume from a snapshot.

        If volume_type extra specs includes 'replication: <is> True'
        the driver needs to create a volume replica (secondary),
        and setup replication between the newly created volume and
        the secondary volume.
        """

        raise NotImplementedError()

    def create_cloned_volume(self, volume, src_vref):
        """Creates a clone of the specified volume.

        If volume_type extra specs includes 'replication: <is> True' the
        driver needs to create a volume replica (secondary)
        and setup replication between the newly created volume
        and the secondary volume.

        """

        raise NotImplementedError()

    def create_replica_test_volume(self, volume, src_vref):
        """Creates a test replica clone of the specified replicated volume.

        Create a clone of the replicated (secondary) volume.

        """
        raise NotImplementedError()

    def delete_volume(self, volume):
        """Deletes a volume.

        If volume_type extra specs includes 'replication: <is> True'
        then the driver needs to delete the volume replica too.

        """
        raise NotImplementedError()

    def create_snapshot(self, snapshot):
        """Creates a snapshot."""
        raise NotImplementedError()

    def delete_snapshot(self, snapshot):
        """Deletes a snapshot."""
        raise NotImplementedError()

    def local_path(self, volume):
        raise NotImplementedError()

    def get_volume_stats(self, refresh=False):
        """Return the current state of the volume service. If 'refresh' is
           True, run the update first.

           For replication the following state should be reported:
           replication_support = True (None or false disables replication)

        """
        return None

    def copy_volume_data(self, context, src_vol, dest_vol, remote=None):
        """Copy data from src_vol to dest_vol."""
        LOG.debug(('copy_data_between_volumes %(src)s -> %(dest)s.')
                  % {'src': src_vol['name'], 'dest': dest_vol['name']})

        properties = utils.brick_get_connector_properties()
        dest_remote = True if remote in ['dest', 'both'] else False
        dest_orig_status = dest_vol['status']
        try:
            dest_attach_info = self._attach_volume(context,
                                                   dest_vol,
                                                   properties,
                                                   remote=dest_remote)
        except Exception:
            with excutils.save_and_reraise_exception():
                msg = _("Failed to attach volume %(vol)s")
                LOG.error(msg % {'vol': dest_vol['id']})
                self.db.volume_update(context, dest_vol['id'],
                                      {'status': dest_orig_status})

        src_remote = True if remote in ['src', 'both'] else False
        src_orig_status = src_vol['status']
        try:
            src_attach_info = self._attach_volume(context,
                                                  src_vol,
                                                  properties,
                                                  remote=src_remote)
        except Exception:
            with excutils.save_and_reraise_exception():
                msg = _("Failed to attach volume %(vol)s")
                LOG.error(msg % {'vol': src_vol['id']})
                self.db.volume_update(context, src_vol['id'],
                                      {'status': src_orig_status})
                self._detach_volume(context, dest_attach_info, dest_vol,
                                    properties, force=True, remote=dest_remote)

        copy_error = True
        try:
            size_in_mb = int(src_vol['size']) * 1024    # vol size is in GB
            volume_utils.copy_volume(
                src_attach_info['device']['path'],
                dest_attach_info['device']['path'],
                size_in_mb,
                self.configuration.volume_dd_blocksize)
            copy_error = False
        except Exception:
            with excutils.save_and_reraise_exception():
                msg = _("Failed to copy volume %(src)s to %(dest)s.")
                LOG.error(msg % {'src': src_vol['id'], 'dest': dest_vol['id']})
        finally:
            self._detach_volume(context, dest_attach_info, dest_vol,
                                properties, force=copy_error,
                                remote=dest_remote)
            self._detach_volume(context, src_attach_info, src_vol,
                                properties, force=copy_error,
                                remote=src_remote)

    def copy_image_to_volume(self, context, volume, image_service, image_id):
        """Fetch the image from image_service and write it to the volume."""
        LOG.debug(('copy_image_to_volume %s.') % volume['name'])

        properties = utils.brick_get_connector_properties()
        attach_info = self._attach_volume(context, volume, properties)

        try:
            image_utils.fetch_to_raw(context,
                                     image_service,
                                     image_id,
                                     attach_info['device']['path'],
                                     self.configuration.volume_dd_blocksize,
                                     size=volume['size'])
        finally:
            self._detach_volume(context, attach_info, volume, properties)

    def copy_volume_to_image(self, context, volume, image_service, image_meta):
        """Copy the volume to the specified image."""
        LOG.debug(('copy_volume_to_image %s.') % volume['name'])

        properties = utils.brick_get_connector_properties()
        attach_info = self._attach_volume(context, volume, properties)

        try:
            image_utils.upload_volume(context,
                                      image_service,
                                      image_meta,
                                      attach_info['device']['path'])
        finally:
            self._detach_volume(context, attach_info, volume, properties)

    def _attach_volume(self, context, volume, properties, remote=False):
        """Attach the volume."""
        if remote:
            # Call remote manager's initialize_connection which includes
            # driver's create_export and initialize_connection
            rpcapi = volume_rpcapi.VolumeAPI()
            conn = rpcapi.initialize_connection(context, volume, properties)
        else:
            # Call local driver's create_export and initialize_connection.
            # NOTE(avishay) This is copied from the manager's code - need to
            # clean this up in the future.
            model_update = None
            try:
                LOG.debug(("Volume %s: creating export"), volume['id'])
                model_update = self.create_export(context, volume)
                if model_update:
                    volume = self.db.volume_update(context, volume['id'],
                                                   model_update)
            except exception.CinderException as ex:
                if model_update:
                    LOG.exception(_LE("Failed updating model of volume "
                                      "%(volume_id)s with driver provided "
                                      "model %(model)s") %
                                  {'volume_id': volume['id'],
                                   'model': model_update})
                    raise exception.ExportFailure(reason=ex)

            try:
                conn = self.initialize_connection(volume, properties)
            except Exception as err:
                try:
                    err_msg = (_('Unable to fetch connection information from '
                                 'backend: %(err)s') % {'err': err})
                    LOG.error(err_msg)
                    LOG.debug("Cleaning up failed connect initialization.")
                    self.remove_export(context, volume)
                except Exception as ex:
                    ex_msg = (_('Error encountered during cleanup '
                                'of a failed attach: %(ex)s') % {'ex': ex})
                    LOG.error(err_msg)
                    raise exception.VolumeBackendAPIException(data=ex_msg)
                raise exception.VolumeBackendAPIException(data=err_msg)

        # Use Brick's code to do attach/detach
        use_multipath = self.configuration.use_multipath_for_image_xfer
        device_scan_attempts = self.configuration.num_volume_device_scan_tries
        protocol = conn['driver_volume_type']
        connector = utils.brick_get_connector(
            protocol,
            use_multipath=use_multipath,
            device_scan_attempts=device_scan_attempts,
            conn=conn)
        device = connector.connect_volume(conn['data'])
        host_device = device['path']

        # Secure network file systems will NOT run as root.
        root_access = not self.secure_file_operations_enabled()

        if not connector.check_valid_device(host_device, root_access):
            raise exception.DeviceUnavailable(path=host_device,
                                              reason=(_("Unable to access "
                                                        "the backend storage "
                                                        "via the path "
                                                        "%(path)s.") %
                                                      {'path': host_device}))
        return {'conn': conn, 'device': device, 'connector': connector}

    def clone_image(self, volume, image_location, image_id, image_meta):
        """Create a volume efficiently from an existing image.

        image_location is a string whose format depends on the
        image service backend in use. The driver should use it
        to determine whether cloning is possible.

        image_id is a string which represents id of the image.
        It can be used by the driver to introspect internal
        stores or registry to do an efficient image clone.

        image_meta is a dictionary that includes 'disk_format' (e.g.
        raw, qcow2) and other image attributes that allow drivers to
        decide whether they can clone the image without first requiring
        conversion.

        Returns a dict of volume properties eg. provider_location,
        boolean indicating whether cloning occurred
        """
        return None, False

    def backup_volume(self, context, backup, backup_service):
        """Create a new backup from an existing volume."""
        volume = self.db.volume_get(context, backup['volume_id'])

        LOG.debug(('Creating a new backup for volume %s.') %
                  volume['name'])

        properties = utils.brick_get_connector_properties()
        attach_info = self._attach_volume(context, volume, properties)

        try:
            volume_path = attach_info['device']['path']

            # Secure network file systems will not chown files.
            if self.secure_file_operations_enabled():
                with fileutils.file_open(volume_path) as volume_file:
                    backup_service.backup(backup, volume_file)
            else:
                with utils.temporary_chown(volume_path):
                    with fileutils.file_open(volume_path) as volume_file:
                        backup_service.backup(backup, volume_file)

        finally:
            self._detach_volume(context, attach_info, volume, properties)

    def restore_backup(self, context, backup, volume, backup_service):
        """Restore an existing backup to a new or existing volume."""
        LOG.debug(('Restoring backup %(backup)s to '
                   'volume %(volume)s.') %
                  {'backup': backup['id'],
                   'volume': volume['name']})

        properties = utils.brick_get_connector_properties()
        attach_info = self._attach_volume(context, volume, properties)

        try:
            volume_path = attach_info['device']['path']

            # Secure network file systems will not chown files.
            if self.secure_file_operations_enabled():
                with fileutils.file_open(volume_path, 'wb') as volume_file:
                    backup_service.restore(backup, volume['id'], volume_file)
            else:
                with utils.temporary_chown(volume_path):
                    with fileutils.file_open(volume_path, 'wb') as volume_file:
                        backup_service.restore(backup, volume['id'],
                                               volume_file)

        finally:
            self._detach_volume(context, attach_info, volume, properties)

    def clear_download(self, context, volume):
        """Clean up after an interrupted image copy."""
        pass

    def extend_volume(self, volume, new_size):
        msg = _("Extend volume not implemented")
        raise NotImplementedError(msg)

    def migrate_volume(self, context, volume, host):
        """Migrate the volume to the specified host.

        Returns a boolean indicating whether the migration occurred, as well as
        model_update.

        :param ctxt: Context
        :param volume: A dictionary describing the volume to migrate
        :param host: A dictionary describing the host to migrate to, where
                     host['host'] is its name, and host['capabilities'] is a
                     dictionary of its reported capabilities.
        """
        return (False, None)

    def retype(self, context, volume, new_type, diff, host):
        """Convert the volume to be of the new type.

        Returns either:
        A boolean indicating whether the retype occurred, or
        A tuple (retyped, model_update) where retyped is a boolean
        indicating if the retype occurred, and the model_update includes
        changes for the volume db.
        if diff['extra_specs'] includes 'replication' then:
            if  ('True', _ ) then replication should be disabled:
                Volume replica should be deleted
                volume['replication_status'] should be changed to 'disabled'
                volume['replication_extended_status'] = None
                volume['replication_driver_data'] = None
            if  (_, 'True') then replication should be enabled:
                Volume replica (secondary) should be created, and replication
                should be setup between the volume and the newly created
                replica
                volume['replication_status'] = 'copying'
                volume['replication_extended_status'] = driver specific value
                volume['replication_driver_data'] = driver specific value

        :param ctxt: Context
        :param volume: A dictionary describing the volume to migrate
        :param new_type: A dictionary describing the volume type to convert to
        :param diff: A dictionary with the difference between the two types
        :param host: A dictionary describing the host to migrate to, where
                     host['host'] is its name, and host['capabilities'] is a
                     dictionary of its reported capabilities.
        """
        return False, None

    def accept_transfer(self, context, volume, new_user, new_project):
        """Accept the transfer of a volume for a new user/project."""
        pass

    def manage_existing(self, volume, existing_ref):
        """Brings an existing backend storage object under Cinder management.

        existing_ref is passed straight through from the API request's
        manage_existing_ref value, and it is up to the driver how this should
        be interpreted.  It should be sufficient to identify a storage object
        that the driver should somehow associate with the newly-created cinder
        volume structure.

        There are two ways to do this:

        1. Rename the backend storage object so that it matches the,
           volume['name'] which is how drivers traditionally map between a
           cinder volume and the associated backend storage object.

        2. Place some metadata on the volume, or somewhere in the backend, that
           allows other driver requests (e.g. delete, clone, attach, detach...)
           to locate the backend storage object when required.

        If the existing_ref doesn't make sense, or doesn't refer to an existing
        backend storage object, raise a ManageExistingInvalidReference
        exception.

        The volume may have a volume_type, and the driver can inspect that and
        compare against the properties of the referenced backend storage
        object.  If they are incompatible, raise a
        ManageExistingVolumeTypeMismatch, specifying a reason for the failure.
        """
        msg = _("Manage existing volume not implemented.")
        raise NotImplementedError(msg)

    def manage_existing_get_size(self, volume, existing_ref):
        """Return size of volume to be managed by manage_existing.

        When calculating the size, round up to the next GB.
        """
        msg = _("Manage existing volume not implemented.")
        raise NotImplementedError(msg)

    def unmanage(self, volume):
        """Removes the specified volume from Cinder management.

        Does not delete the underlying backend storage object.

        For most drivers, this will not need to do anything.  However, some
        drivers might use this call as an opportunity to clean up any
        Cinder-specific configuration that they have associated with the
        backend storage object.
        """
        pass

    def attach_volume(self, context, volume, instance_uuid, host_name,
                      mountpoint):
        """Callback for volume attached to instance or host."""
        pass

    def detach_volume(self, context, volume):
        """Callback for volume detached."""
        pass

    def do_setup(self, context):
        """Any initialization the volume driver does while starting."""
        pass

    def validate_connector(self, connector):
        """Fail if connector doesn't contain all the data needed by driver."""
        pass

    @staticmethod
    def validate_connector_has_setting(connector, setting):
        pass

    def reenable_replication(self, context, volume):
        """Re-enable replication between the replica and primary volume.

        This is used to re-enable/fix the replication between primary
        and secondary. One use is as part of the fail-back process, when
        you re-synchorize your old primary with the promoted volume
        (the old replica).
        Returns model_update for the volume to reflect the actions of the
        driver.
        The driver is expected to update the following entries:
            'replication_status'
            'replication_extended_status'
            'replication_driver_data'
        Possible 'replication_status' values (in model_update) are:
        'error' - replication in error state
        'copying' - replication copying data to secondary (inconsistent)
        'active' - replication copying data to secondary (consistent)
        'active-stopped' - replication data copy on hold (consistent)
        'inactive' - replication data copy on hold (inconsistent)
        Values in 'replication_extended_status' and 'replication_driver_data'
        are managed by the driver.

        :param context: Context
        :param volume: A dictionary describing the volume

        """
        msg = _("sync_replica not implemented.")
        raise NotImplementedError(msg)

    def get_replication_status(self, context, volume):
        """Query the actual volume replication status from the driver.

        Returns model_update for the volume.
        The driver is expected to update the following entries:
            'replication_status'
            'replication_extended_status'
            'replication_driver_data'
        Possible 'replication_status' values (in model_update) are:
        'error' - replication in error state
        'copying' - replication copying data to secondary (inconsistent)
        'active' - replication copying data to secondary (consistent)
        'active-stopped' - replication data copy on hold (consistent)
        'inactive' - replication data copy on hold (inconsistent)
        Values in 'replication_extended_status' and 'replication_driver_data'
        are managed by the driver.

        :param context: Context
        :param volume: A dictionary describing the volume
        """
        return None

    def promote_replica(self, context, volume):
        """Promote the replica to be the primary volume.

        Following this command, replication between the volumes at
        the storage level should be stopped, the replica should be
        available to be attached, and the replication status should
        be in status 'inactive'.

        Returns model_update for the volume.
        The driver is expected to update the following entries:
            'replication_status'
            'replication_extended_status'
            'replication_driver_data'
        Possible 'replication_status' values (in model_update) are:
        'error' - replication in error state
        'inactive' - replication data copy on hold (inconsistent)
        Values in 'replication_extended_status' and 'replication_driver_data'
        are managed by the driver.

        :param context: Context
        :param volume: A dictionary describing the volume
        """
        msg = _("promote_replica not implemented.")
        raise NotImplementedError(msg)

    # #######  Interface methods for DataPath (Connector) ########
    def ensure_export(self, context, volume):
        """Synchronously recreates an export for a volume."""
        raise NotImplementedError()

    def create_export(self, context, volume):
        """Exports the volume.

        Can optionally return a Dictionary of changes
        to the volume object to be persisted.
        """
        raise NotImplementedError()

    def remove_export(self, context, volume):
        """Removes an export for a volume."""
        raise NotImplementedError()

    def initialize_connection(self, volume, connector):
        """Allow connection to connector and return connection info."""
        raise NotImplementedError()

    def terminate_connection(self, volume, connector, **kwargs):
        """Disallow connection from connector"""

    def create_consistencygroup(self, context, group):
        """Creates a consistencygroup."""
        raise NotImplementedError()

    def delete_consistencygroup(self, context, group):
        """Deletes a consistency group."""
        raise NotImplementedError()

    def create_cgsnapshot(self, context, cgsnapshot):
        """Creates a cgsnapshot."""
        raise NotImplementedError()

    def delete_cgsnapshot(self, context, cgsnapshot):
        """Deletes a cgsnapshot."""
        raise NotImplementedError()

    def get_pool(self, volume):
        """Return pool name where volume reside on.

        :param volume: The volume hosted by the the driver.
        :return: name of the pool where given volume is in.
        """
        return None

    def secure_file_operations_enabled(self):
        """Determine if driver is running in Secure File Operations mode.

        The Cinder Volume driver needs to query if this driver is running
        in a secure file operations mode. By default, it is False: any driver
        that does support secure file operations should override this method.
        """
        return False

    def update_migrated_volume(self, ctxt, volume, new_volume):
        """Return model update for migrated volume.

        :param volume: The original volume that was migrated to this backend
        :param new_volume: The migration volume object that was created on
                           this backend as part of the migration process
        :return model_update to update DB with any needed changes
        """
        return None


class ISCSIDriver(VolumeDriver):
    """Executes commands relating to ISCSI volumes.

    We make use of model provider properties as follows:

    ``provider_location``
      if present, contains the iSCSI target information in the same
      format as an ietadm discovery
      i.e. '<ip>:<port>,<portal> <target IQN>'

    ``provider_auth``
      if present, contains a space-separated triple:
      '<auth method> <auth username> <auth password>'.
      `CHAP` is the only auth_method in use at the moment.
    """

    def __init__(self, *args, **kwargs):
        super(ISCSIDriver, self).__init__(*args, **kwargs)

    def _do_iscsi_discovery(self, volume):
        # TODO(justinsb): Deprecate discovery and use stored info
        # NOTE(justinsb): Discovery won't work with CHAP-secured targets (?)
        LOG.warn(_("ISCSI provider_location not stored, using discovery"))

        volume_name = volume['name']

        try:
            # NOTE(griff) We're doing the split straight away which should be
            # safe since using '@' in hostname is considered invalid

            (out, _err) = self._execute('iscsiadm', '-m', 'discovery',
                                        '-t', 'sendtargets', '-p',
                                        volume['host'].split('@')[0],
                                        run_as_root=True)
        except processutils.ProcessExecutionError as ex:
            LOG.error(_("ISCSI discovery attempt failed for:%s") %
                      volume['host'].split('@')[0])
            LOG.debug("Error from iscsiadm -m discovery: %s" % ex.stderr)
            return None

        for target in out.splitlines():
            if (self.configuration.iscsi_ip_address in target
                    and volume_name in target):
                return target
        return None

    def _get_iscsi_properties(self, volume):
        """Gets iscsi configuration

        We ideally get saved information in the volume entity, but fall back
        to discovery if need be. Discovery may be completely removed in future
        The properties are:

        :target_discovered:    boolean indicating whether discovery was used

        :target_iqn:    the IQN of the iSCSI target

        :target_portal:    the portal of the iSCSI target

        :target_lun:    the lun of the iSCSI target

        :volume_id:    the id of the volume (currently used by xen)

        :auth_method:, :auth_username:, :auth_password:

            the authentication details. Right now, either auth_method is not
            present meaning no authentication, or auth_method == `CHAP`
            meaning use CHAP with the specified credentials.

        :access_mode:    the volume access mode allow client used
                         ('rw' or 'ro' currently supported)
        """

        properties = {}

        location = volume['provider_location']

        if location:
            # provider_location is the same format as iSCSI discovery output
            properties['target_discovered'] = False
        else:
            location = self._do_iscsi_discovery(volume)

            if not location:
                msg = (_("Could not find iSCSI export for volume %s") %
                        (volume['name']))
                raise exception.InvalidVolume(reason=msg)

            LOG.debug("ISCSI Discovery: Found %s" % (location))
            properties['target_discovered'] = True

        results = location.split(" ")
        properties['target_portal'] = results[0].split(",")[0]
        properties['target_iqn'] = results[1]
        try:
            properties['target_lun'] = int(results[2])
        except (IndexError, ValueError):
            if (self.configuration.volume_driver in
                    ['cinder.volume.drivers.lvm.LVMISCSIDriver',
                     'cinder.volume.drivers.lvm.LVMISERDriver',
                     'cinder.volume.drivers.lvm.ThinLVMVolumeDriver'] and
                    self.configuration.iscsi_helper in ('tgtadm', 'iseradm')):
                properties['target_lun'] = 1
            else:
                properties['target_lun'] = 0

        properties['volume_id'] = volume['id']

        auth = volume['provider_auth']
        if auth:
            (auth_method, auth_username, auth_secret) = auth.split()

            properties['auth_method'] = auth_method
            properties['auth_username'] = auth_username
            properties['auth_password'] = auth_secret

        geometry = volume.get('provider_geometry', None)
        if geometry:
            (physical_block_size, logical_block_size) = geometry.split()
            properties['physical_block_size'] = physical_block_size
            properties['logical_block_size'] = logical_block_size

        encryption_key_id = volume.get('encryption_key_id', None)
        properties['encrypted'] = encryption_key_id is not None

        return properties

    def _run_iscsiadm(self, iscsi_properties, iscsi_command, **kwargs):
        check_exit_code = kwargs.pop('check_exit_code', 0)
        (out, err) = self._execute('iscsiadm', '-m', 'node', '-T',
                                   iscsi_properties['target_iqn'],
                                   '-p', iscsi_properties['target_portal'],
                                   *iscsi_command, run_as_root=True,
                                   check_exit_code=check_exit_code)
        LOG.debug("iscsiadm %s: stdout=%s stderr=%s" %
                  (iscsi_command, out, err))
        return (out, err)

    def _run_iscsiadm_bare(self, iscsi_command, **kwargs):
        check_exit_code = kwargs.pop('check_exit_code', 0)
        (out, err) = self._execute('iscsiadm',
                                   *iscsi_command,
                                   run_as_root=True,
                                   check_exit_code=check_exit_code)
        LOG.debug("iscsiadm %s: stdout=%s stderr=%s" %
                  (iscsi_command, out, err))
        return (out, err)

    def _iscsiadm_update(self, iscsi_properties, property_key, property_value,
                         **kwargs):
        iscsi_command = ('--op', 'update', '-n', property_key,
                         '-v', property_value)
        return self._run_iscsiadm(iscsi_properties, iscsi_command, **kwargs)

    def initialize_connection(self, volume, connector):
        """Initializes the connection and returns connection info.

        The iscsi driver returns a driver_volume_type of 'iscsi'.
        The format of the driver data is defined in _get_iscsi_properties.
        Example return value::

            {
                'driver_volume_type': 'iscsi'
                'data': {
                    'target_discovered': True,
                    'target_iqn': 'iqn.2010-10.org.openstack:volume-00000001',
                    'target_portal': '127.0.0.0.1:3260',
                    'volume_id': 1,
                    'access_mode': 'rw'
                }
            }

        """

        if CONF.iscsi_helper == 'lioadm':
            self.target_helper.initialize_connection(volume, connector)

        iscsi_properties = self._get_iscsi_properties(volume)
        return {
            'driver_volume_type': 'iscsi',
            'data': iscsi_properties
        }

    def validate_connector(self, connector):
        # iSCSI drivers require the initiator information
        if 'initiator' not in connector:
            err_msg = (_('The volume driver requires the iSCSI initiator '
                         'name in the connector.'))
            LOG.error(err_msg)
            raise exception.VolumeBackendAPIException(data=err_msg)

    def terminate_connection(self, volume, connector, **kwargs):
        if CONF.iscsi_helper == 'lioadm':
            self.target_helper.terminate_connection(volume, connector)

    def get_volume_stats(self, refresh=False):
        """Get volume stats.

        If 'refresh' is True, run update the stats first.
        """
        if refresh:
            self._update_volume_stats()

        return self._stats

    def _update_volume_stats(self):
        """Retrieve stats info from volume group."""

        LOG.debug("Updating volume stats")
        data = {}
        backend_name = self.configuration.safe_get('volume_backend_name')
        data["volume_backend_name"] = backend_name or 'Generic_iSCSI'
        data["vendor_name"] = 'Open Source'
        data["driver_version"] = '1.0'
        data["storage_protocol"] = 'iSCSI'
        data["pools"] = []

        if self.pools:
            for pool in self.pools:
                new_pool = {}
                new_pool.update(dict(
                    pool_name=pool,
                    total_capacity_gb=0,
                    free_capacity_gb=0,
                    reserved_percentage=100,
                    QoS_support=False
                ))
                data["pools"].append(new_pool)
        else:
            # No pool configured, the whole backend will be treated as a pool
            single_pool = {}
            single_pool.update(dict(
                pool_name=data["volume_backend_name"],
                total_capacity_gb=0,
                free_capacity_gb=0,
                reserved_percentage=100,
                QoS_support=False
            ))
            data["pools"].append(single_pool)
        self._stats = data

    def get_target_helper(self, db):
        root_helper = utils.get_root_helper()
        if CONF.iscsi_helper == 'iseradm':
            return iscsi.ISERTgtAdm(root_helper, CONF.volumes_dir,
                                    CONF.iscsi_target_prefix, db=db)
        elif CONF.iscsi_helper == 'tgtadm':
            return iscsi.TgtAdm(root_helper,
                                CONF.volumes_dir,
                                CONF.iscsi_target_prefix,
                                db=db)
        elif CONF.iscsi_helper == 'fake':
            return iscsi.FakeIscsiHelper()
        elif CONF.iscsi_helper == 'lioadm':
            return iscsi.LioAdm(root_helper,
                                CONF.lio_initiator_iqns,
                                CONF.iscsi_target_prefix, db=db)
        else:
            return iscsi.IetAdm(root_helper, CONF.iet_conf, CONF.iscsi_iotype,
                                db=db)


class FakeISCSIDriver(ISCSIDriver):
    """Logs calls instead of executing."""
    def __init__(self, *args, **kwargs):
        super(FakeISCSIDriver, self).__init__(execute=self.fake_execute,
                                              *args, **kwargs)

    def create_volume(self, volume):
        pass

    def check_for_setup_error(self):
        """No setup necessary in fake mode."""
        pass

    def initialize_connection(self, volume, connector):
        return {
            'driver_volume_type': 'iscsi',
            'data': {'access_mode': 'rw'}
        }

    def terminate_connection(self, volume, connector, **kwargs):
        pass

    @staticmethod
    def fake_execute(cmd, *_args, **_kwargs):
        """Execute that simply logs the command."""
        LOG.debug("FAKE ISCSI: %s", cmd)
        return (None, None)

    def create_volume_from_snapshot(self, volume, snapshot):
        """Creates a volume from a snapshot."""
        pass

    def create_cloned_volume(self, volume, src_vref):
        """Creates a clone of the specified volume."""
        pass

    def delete_volume(self, volume):
        """Deletes a volume."""
        pass

    def create_snapshot(self, snapshot):
        """Creates a snapshot."""
        pass

    def delete_snapshot(self, snapshot):
        """Deletes a snapshot."""
        pass

    def local_path(self, volume):
        return '/tmp/volume-%s' % volume.id

    def ensure_export(self, context, volume):
        """Synchronously recreates an export for a volume."""
        pass

    def create_export(self, context, volume):
        """Exports the volume. Can optionally return a Dictionary of changes
        to the volume object to be persisted.
        """
        pass

    def remove_export(self, context, volume):
        """Removes an export for a volume."""
        pass


class ISERDriver(ISCSIDriver):
    """Executes commands relating to ISER volumes.

    We make use of model provider properties as follows:

    ``provider_location``
      if present, contains the iSER target information in the same
      format as an ietadm discovery
      i.e. '<ip>:<port>,<portal> <target IQN>'

    ``provider_auth``
      if present, contains a space-separated triple:
      '<auth method> <auth username> <auth password>'.
      `CHAP` is the only auth_method in use at the moment.
    """
    def __init__(self, *args, **kwargs):
        super(ISERDriver, self).__init__(*args, **kwargs)
        # for backward compatibility
        self.configuration.num_volume_device_scan_tries = \
            self.configuration.num_iser_scan_tries
        self.configuration.iscsi_num_targets = \
            self.configuration.iser_num_targets
        self.configuration.iscsi_target_prefix = \
            self.configuration.iser_target_prefix
        self.configuration.iscsi_ip_address = \
            self.configuration.iser_ip_address
        self.configuration.iscsi_port = self.configuration.iser_port

    def initialize_connection(self, volume, connector):
        """Initializes the connection and returns connection info.

        The iser driver returns a driver_volume_type of 'iser'.
        The format of the driver data is defined in _get_iser_properties.
        Example return value::

            {
                'driver_volume_type': 'iser'
                'data': {
                    'target_discovered': True,
                    'target_iqn':
                    'iqn.2010-10.org.iser.openstack:volume-00000001',
                    'target_portal': '127.0.0.0.1:3260',
                    'volume_id': 1,
                }
            }

        """

        iser_properties = self._get_iscsi_properties(volume)
        return {
            'driver_volume_type': 'iser',
            'data': iser_properties
        }

    def _update_volume_stats(self):
        """Retrieve stats info from volume group."""

        LOG.debug("Updating volume stats")
        data = {}
        backend_name = self.configuration.safe_get('volume_backend_name')
        data["volume_backend_name"] = backend_name or 'Generic_iSER'
        data["vendor_name"] = 'Open Source'
        data["driver_version"] = '1.0'
        data["storage_protocol"] = 'iSER'
        data["pools"] = []

        if self.pools:
            for pool in self.pools:
                new_pool = {}
                new_pool.update(dict(
                    pool_name=pool,
                    total_capacity_gb=0,
                    free_capacity_gb=0,
                    reserved_percentage=100,
                    QoS_support=False
                ))
                data["pools"].append(new_pool)
        else:
            # No pool configured, the whole backend will be treated as a pool
            single_pool = {}
            single_pool.update(dict(
                pool_name=data["volume_backend_name"],
                total_capacity_gb=0,
                free_capacity_gb=0,
                reserved_percentage=100,
                QoS_support=False
            ))
            data["pools"].append(single_pool)
        self._stats = data

    def get_target_helper(self, db):
        root_helper = utils.get_root_helper()

        if CONF.iser_helper == 'fake':
            return iscsi.FakeIscsiHelper()
        else:
            return iscsi.ISERTgtAdm(root_helper,
                                    CONF.volumes_dir, db=db)


class FakeISERDriver(FakeISCSIDriver):
    """Logs calls instead of executing."""
    def __init__(self, *args, **kwargs):
        super(FakeISERDriver, self).__init__(execute=self.fake_execute,
                                             *args, **kwargs)

    def initialize_connection(self, volume, connector):
        return {
            'driver_volume_type': 'iser',
            'data': {}
        }

    @staticmethod
    def fake_execute(cmd, *_args, **_kwargs):
        """Execute that simply logs the command."""
        LOG.debug("FAKE ISER: %s", cmd)
        return (None, None)


class FibreChannelDriver(VolumeDriver):
    """Executes commands relating to Fibre Channel volumes."""
    def __init__(self, *args, **kwargs):
        super(FibreChannelDriver, self).__init__(*args, **kwargs)

    def initialize_connection(self, volume, connector):
        """Initializes the connection and returns connection info.

        The  driver returns a driver_volume_type of 'fibre_channel'.
        The target_wwn can be a single entry or a list of wwns that
        correspond to the list of remote wwn(s) that will export the volume.
        Example return values:

            {
                'driver_volume_type': 'fibre_channel'
                'data': {
                    'target_discovered': True,
                    'target_lun': 1,
                    'target_wwn': '1234567890123',
                    'access_mode': 'rw'
                }
            }

            or

             {
                'driver_volume_type': 'fibre_channel'
                'data': {
                    'target_discovered': True,
                    'target_lun': 1,
                    'target_wwn': ['1234567890123', '0987654321321'],
                    'access_mode': 'rw'
                }
            }

        """
        msg = _("Driver must implement initialize_connection")
        raise NotImplementedError(msg)

    def validate_connector(self, connector):
        """Fail if connector doesn't contain all the data needed by driver.

        Do a check on the connector and ensure that it has wwnns, wwpns.
        """
        self.validate_connector_has_setting(connector, 'wwpns')
        self.validate_connector_has_setting(connector, 'wwnns')

    @staticmethod
    def validate_connector_has_setting(connector, setting):
        """Test for non-empty setting in connector."""
        if setting not in connector or not connector[setting]:
            msg = (_(
                "FibreChannelDriver validate_connector failed. "
                "No '%s'. Make sure HBA state is Online.") % setting)
            LOG.error(msg)
            raise exception.VolumeDriverException(message=msg)
