text: # Copyright (c) 2013 The Johns Hopkins University/Applied Physics Laboratory
  # 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.
  
  
  from oslo_log import log as logging
  from oslo_utils import importutils
  
  from patron.i18n import _LE
  from patron.volume.encryptors import nop
  
  
  LOG = logging.getLogger(__name__)
  
  
  def get_volume_encryptor(connection_info, **kwargs):
      """Creates a VolumeEncryptor used to encrypt the specified volume.
  
      :param: the connection information used to attach the volume
      :returns VolumeEncryptor: the VolumeEncryptor for the volume
      """
      encryptor = nop.NoOpEncryptor(connection_info, **kwargs)
  
      location = kwargs.get('control_location', None)
      if location and location.lower() == 'front-end':  # case insensitive
          provider = kwargs.get('provider')
  
          if provider == 'LuksEncryptor':
              provider = 'patron.volume.encryptors.luks.' + provider
          elif provider == 'CryptsetupEncryptor':
              provider = 'patron.volume.encryptors.cryptsetup.' + provider
          elif provider == 'NoOpEncryptor':
              provider = 'patron.volume.encryptors.nop.' + provider
          try:
              encryptor = importutils.import_object(provider, connection_info,
                                                    **kwargs)
          except Exception as e:
              LOG.error(_LE("Error instantiating %(provider)s: %(exception)s"),
                        {'provider': provider, 'exception': e})
              raise
  
      return encryptor
  
  
  def get_encryption_metadata(context, volume_api, volume_id, connection_info):
      metadata = {}
      if ('data' in connection_info and
              connection_info['data'].get('encrypted', False)):
          try:
              metadata = volume_api.get_volume_encryption_metadata(context,
                                                                   volume_id)
          except Exception as e:
              LOG.error(_LE("Failed to retrieve encryption metadata for "
                            "volume %(volume_id)s: %(exception)s"),
                        {'volume_id': volume_id, 'exception': e})
              raise
  
      return metadata
  