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 sqlalchemy import Column, ForeignKey, MetaData, Table
  from sqlalchemy import Boolean, DateTime, Integer, String
  
  from cinder.i18n import _
  from cinder.openstack.common import log as logging
  
  
  LOG = logging.getLogger(__name__)
  
  
  def upgrade(migrate_engine):
      meta = MetaData(bind=migrate_engine)
  
      # encryption key UUID -- must be stored per volume
      volumes = Table('volumes', meta, autoload=True)
      encryption_key = Column('encryption_key_id', String(36))
      try:
          volumes.create_column(encryption_key)
      except Exception:
          LOG.error(_("Column |%s| not created!"), repr(encryption_key))
          raise
  
      # encryption key UUID and volume type id -- must be stored per snapshot
      snapshots = Table('snapshots', meta, autoload=True)
      encryption_key = Column('encryption_key_id', String(36))
      try:
          snapshots.create_column(encryption_key)
      except Exception:
          LOG.error(_("Column |%s| not created!"), repr(encryption_key))
          raise
      volume_type = Column('volume_type_id', String(36))
      try:
          snapshots.create_column(volume_type)
      except Exception:
          LOG.error(_("Column |%s| not created!"), repr(volume_type))
          raise
  
      volume_types = Table('volume_types', meta, autoload=True)
  
      # encryption types associated with particular volume type
      encryption = Table(
          'encryption', meta,
          Column('created_at', DateTime(timezone=False)),
          Column('updated_at', DateTime(timezone=False)),
          Column('deleted_at', DateTime(timezone=False)),
          Column('deleted', Boolean(create_constraint=True, name=None)),
          Column('cipher', String(length=255)),
          Column('control_location', String(length=255), nullable=False),
          Column('key_size', Integer),
          Column('provider', String(length=255), nullable=False),
          # NOTE(joel-coffman): The volume_type_id must be unique or else the
          # referenced volume type becomes ambiguous. That is, specifying the
          # volume type is not sufficient to identify a particular encryption
          # scheme unless each volume type is associated with at most one
          # encryption scheme.
          Column('volume_type_id', String(length=36),
                 ForeignKey(volume_types.c.id),
                 primary_key=True, nullable=False),
          mysql_engine='InnoDB',
          mysql_charset='utf8'
      )
  
      try:
          encryption.create()
      except Exception:
          LOG.error(_("Table |%s| not created!"), repr(encryption))
          raise
  
  
  def downgrade(migrate_engine):
      meta = MetaData(bind=migrate_engine)
  
      # drop encryption key UUID for volumes
      volumes = Table('volumes', meta, autoload=True)
      try:
          volumes.c.encryption_key_id.drop()
      except Exception:
          LOG.error(_("encryption_key_id column not dropped from volumes"))
          raise
  
      # drop encryption key UUID and volume type id for snapshots
      snapshots = Table('snapshots', meta, autoload=True)
      try:
          snapshots.c.encryption_key_id.drop()
      except Exception:
          LOG.error(_("encryption_key_id column not dropped from snapshots"))
          raise
      try:
          snapshots.c.volume_type_id.drop()
      except Exception:
          LOG.error(_("volume_type_id column not dropped from snapshots"))
          raise
  
      # drop encryption types table
      encryption = Table('encryption', meta, autoload=True)
      try:
          encryption.drop()
      except Exception:
          LOG.error(_("encryption table not dropped"))
          raise
  