text: #    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.
  """Libvirt volume driver for iSCSI"""
  
  from os_brick import exception as os_brick_exception
  from os_brick import initiator
  from os_brick.initiator import connector
  from oslo_log import log as logging
  
  import nova.conf
  from nova import utils
  from nova.virt.libvirt.volume import volume as libvirt_volume
  
  LOG = logging.getLogger(__name__)
  
  CONF = nova.conf.CONF
  
  
  class LibvirtISCSIVolumeDriver(libvirt_volume.LibvirtBaseVolumeDriver):
      """Driver to attach Network volumes to libvirt."""
  
      def __init__(self, host):
          super(LibvirtISCSIVolumeDriver, self).__init__(host,
                                                         is_block_dev=True)
  
          # Call the factory here so we can support
          # more than x86 architectures.
          self.connector = connector.InitiatorConnector.factory(
              initiator.ISCSI, utils.get_root_helper(),
              use_multipath=CONF.libvirt.volume_use_multipath,
              device_scan_attempts=CONF.libvirt.num_volume_scan_tries,
              transport=self._get_transport())
  
      def _get_transport(self):
          if CONF.libvirt.iscsi_iface:
              transport = CONF.libvirt.iscsi_iface
          else:
              transport = 'default'
  
          return transport
  
      def get_config(self, connection_info, disk_info):
          """Returns xml for libvirt."""
          conf = super(LibvirtISCSIVolumeDriver,
                       self).get_config(connection_info, disk_info)
          conf.source_type = "block"
          conf.source_path = connection_info['data']['device_path']
          conf.driver_io = "native"
          return conf
  
      def connect_volume(self, connection_info, instance):
          """Attach the volume to instance_name."""
  
          LOG.debug("Calling os-brick to attach iSCSI Volume", instance=instance)
          device_info = self.connector.connect_volume(connection_info['data'])
          LOG.debug("Attached iSCSI volume %s", device_info, instance=instance)
  
          connection_info['data']['device_path'] = device_info['path']
  
      def disconnect_volume(self, connection_info, instance):
          """Detach the volume from instance_name."""
  
          LOG.debug("calling os-brick to detach iSCSI Volume", instance=instance)
          try:
              self.connector.disconnect_volume(connection_info['data'], None)
          except os_brick_exception.VolumeDeviceNotFound as exc:
              LOG.warning('Ignoring VolumeDeviceNotFound: %s', exc)
              return
          LOG.debug("Disconnected iSCSI Volume", instance=instance)
  
          super(LibvirtISCSIVolumeDriver,
                self).disconnect_volume(connection_info, instance)
  
      def extend_volume(self, connection_info, instance, requested_size):
          """Extend the volume."""
          LOG.debug("calling os-brick to extend iSCSI Volume", instance=instance)
          new_size = self.connector.extend_volume(connection_info['data'])
          LOG.debug("Extend iSCSI Volume: new_size=%s",
                    new_size, instance=instance)
          return new_size
  