This change proposes the use of Alembic to manage Glance migrations.
* Introduce new directory ``alembic_migrations`` under
``glance/db/sqlalchemy``. This directory is the home for all glance
migrations henceforth. All the migration scripts reside under
``versions`` directory.
* All the migrations up to Liberty are consolidated into one migration
called ``liberty_initial`` as those migrations are not supported
any more. Mitaka migrations are retained but under a different naming
convention.
* All the glance manage db commands are changed appropriately. They now
use alembic to perform operations such as ``version``, ``upgrade``,
``sync`` and ``version_control``.
* The database versions are not numerical any more. They are the revision
ID of the last migration applied on the database. Since we don't
support migrations before Mitaka, the Liberty version ``42`` will now
appear as ``liberty``. Migration ``43`` and ``44`` in Mitaka appear as
``mitaka01`` and ``mitaka02`` respectively.
* When one performs a ``sync`` or ``upgrade`` command, the database is
first stamped with an equivalent alembic version before upgrading.
* The older migration scripts are retained so that users can correlate
with the new migrations. Also, it is probably safe to retain them until
the alembic migrations become stable. Similarly, the ``migrate_version``
table is not removed yet.
Partially-Implements: blueprint alembic-migrations
Change-Id: Ie8594ff339a13bf190aefa308f54e97ee20ecfa2
Co-Authored-By: Alexander Bashmakov <alexander.bashmakov@intel.com>
Depends-On: I1596499529af249bc48dfe859bbd31e90c48a5e0
21d431013f