OpenStack Common DB Code
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# 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.
import os
import alembic
from alembic import config as alembic_config
import alembic.migration as alembic_migration
from alembic import script as alembic_script
from oslo_db.sqlalchemy.migration_cli import ext_base
class AlembicExtension(ext_base.MigrationExtensionBase):
"""Extension to provide alembic features.
:param engine: SQLAlchemy engine instance for a given database
:type engine: sqlalchemy.engine.Engine
:param migration_config: Stores specific configuration for migrations
:type migration_config: dict
"""
order = 2
@property
def enabled(self):
return os.path.exists(self.alembic_ini_path)
def __init__(self, engine, migration_config):
self.alembic_ini_path = migration_config.get('alembic_ini_path', '')
self.config = alembic_config.Config(self.alembic_ini_path)
# option should be used if script is not in default directory
repo_path = migration_config.get('alembic_repo_path')
if repo_path:
self.config.set_main_option('script_location', repo_path)
self.engine = engine
def upgrade(self, version):
with self.engine.begin() as connection:
self.config.attributes['connection'] = connection
return alembic.command.upgrade(self.config, version or 'head')
def downgrade(self, version):
if isinstance(version, int) or version is None or version.isdigit():
version = 'base'
with self.engine.begin() as connection:
self.config.attributes['connection'] = connection
return alembic.command.downgrade(self.config, version)
def version(self):
with self.engine.connect() as conn:
context = alembic_migration.MigrationContext.configure(conn)
return context.get_current_revision()
def revision(self, message='', autogenerate=False):
"""Creates template for migration.
:param message: Text that will be used for migration title
:type message: string
:param autogenerate: If True - generates diff based on current database
state
:type autogenerate: bool
"""
with self.engine.begin() as connection:
self.config.attributes['connection'] = connection
return alembic.command.revision(self.config, message=message,
autogenerate=autogenerate)
def stamp(self, revision):
"""Stamps database with provided revision.
:param revision: Should match one from repository or head - to stamp
database with most recent revision
:type revision: string
"""
with self.engine.begin() as connection:
self.config.attributes['connection'] = connection
return alembic.command.stamp(self.config, revision=revision)
def has_revision(self, rev_id):
if rev_id in ['base', 'head']:
return True
# Although alembic supports relative upgrades and downgrades,
# get_revision always returns False for relative revisions.
# Since only alembic supports relative revisions, assume the
# revision belongs to this plugin.
if rev_id: # rev_id can be None, so the check is required
if '-' in rev_id or '+' in rev_id:
return True
script = alembic_script.ScriptDirectory(
self.config.get_main_option('script_location'))
try:
script.get_revision(rev_id)
return True
except alembic.util.CommandError:
return False