1 files changed, 117 insertions, 0 deletions
diff --git a/heat/db/migration.py b/heat/db/migration.py
new file mode 100644
index 000000000..910656ca1
--- /dev/null
+++ b/heat/db/migration.py
@@ -0,0 +1,117 @@
+#    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
+
+from alembic import command as alembic_api
+from alembic import config as alembic_config
+from alembic import migration as alembic_migration
+from oslo_log import log as logging
+import sqlalchemy as sa
+
+from heat.db import api as db_api
+
+LOG = logging.getLogger(__name__)
+
+ALEMBIC_INIT_VERSION = 'c6214ca60943'
+
+
+def _migrate_legacy_database(engine, connection, config):
+    """Check if database is a legacy sqlalchemy-migrate-managed database.
+
+    If it is, migrate it by "stamping" the initial alembic schema.
+    """
+    # If the database doesn't have the sqlalchemy-migrate legacy migration
+    # table, we don't have anything to do
+    if not sa.inspect(engine).has_table('migrate_version'):
+        return
+
+    # Likewise, if we've already migrated to alembic, we don't have anything to
+    # do
+    context = alembic_migration.MigrationContext.configure(connection)
+    if context.get_current_revision():
+        return
+
+    # We have legacy migrations but no alembic migration. Stamp (dummy apply)
+    # the initial alembic migration.
+
+    LOG.info(
+        'The database is still under sqlalchemy-migrate control; '
+        'fake applying the initial alembic migration'
+    )
+    alembic_api.stamp(config, ALEMBIC_INIT_VERSION)
+
+
+def _find_alembic_conf():
+    """Get the project's alembic configuration
+
+    :returns: An instance of ``alembic.config.Config``
+    """
+    path = os.path.join(
+        os.path.abspath(os.path.dirname(__file__)),
+        'alembic.ini',
+    )
+    config = alembic_config.Config(os.path.abspath(path))
+    # we don't want to use the logger configuration from the file, which is
+    # only really intended for the CLI
+    # https://stackoverflow.com/a/42691781/613428
+    config.attributes['configure_logger'] = False
+    return config
+
+
+def _upgrade_alembic(engine, config, version):
+    # re-use the connection rather than creating a new one
+    with engine.begin() as connection:
+        config.attributes['connection'] = connection
+        _migrate_legacy_database(engine, connection, config)
+        alembic_api.upgrade(config, version or 'head')
+
+
+def db_sync(version=None, engine=None):
+    """Migrate the database to `version` or the most recent version."""
+    # if the user requested a specific version, check if it's an integer: if
+    # so, we're almost certainly in sqlalchemy-migrate land and won't support
+    # that
+    if version is not None and version.isdigit():
+        raise ValueError(
+            'You requested an sqlalchemy-migrate database version; this is '
+            'no longer supported'
+        )
+
+    if engine is None:
+        engine = db_api.get_engine()
+
+    config = _find_alembic_conf()
+
+    # discard the URL encoded in alembic.ini in favour of the URL configured
+    # for the engine by the database fixtures, casting from
+    # 'sqlalchemy.engine.url.URL' to str in the process. This returns a
+    # RFC-1738 quoted URL, which means that a password like "foo@" will be
+    # turned into "foo%40". This in turns causes a problem for
+    # set_main_option() because that uses ConfigParser.set, which (by design)
+    # uses *python* interpolation to write the string out ... where "%" is the
+    # special python interpolation character! Avoid this mismatch by quoting
+    # all %'s for the set below.
+    engine_url = str(engine.url).replace('%', '%%')
+    config.set_main_option('sqlalchemy.url', str(engine_url))
+
+    LOG.info('Applying migration(s)')
+    _upgrade_alembic(engine, config, version)
+    LOG.info('Migration(s) applied')
+
+
+def db_version():
+    """Get database version."""
+    engine = db_api.get_engine()
+    with engine.connect() as connection:
+        m_context = alembic_migration.MigrationContext.configure(connection)
+        return m_context.get_current_revision()