Deprecate 'oslo_db.sqlalchemy.migration' module

This module hasn't been touched with years and 'sqlalchemy-migrate' is
effectively abandoned. It's time to drop support for this an encourage
the laggards to switch to alembic and use it directly.

Change-Id: I59335b4f318bae2e29ab139cdea089a4d6e14305
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

oslo_db/sqlalchemy/migration.py

@@ -41,6 +41,7 @@
 
 import os
 
+from debtcollector import removals
 from migrate import exceptions as versioning_exceptions
 from migrate.versioning import api as versioning_api
 from migrate.versioning.repository import Repository
@@ -50,6 +51,13 @@ from oslo_db._i18n import _
 from oslo_db import exception
 
 
+_removed_msg = (
+    'sqlalchemy-migrate support in oslo_db is deprecated; consider '
+    'migrating to alembic'
+)
+
+
+@removals.remove(message=_removed_msg, version='8.3.0')
 def db_sync(engine, abs_path, version=None, init_version=0, sanity_check=True):
     """Upgrade or downgrade a database.
 
@@ -116,6 +124,7 @@ def _db_schema_sanity_check(engine):
                                ) % ','.join(table_names))
 
 
+@removals.remove(message=_removed_msg, version='8.3.0')
 def db_version(engine, abs_path, init_version):
     """Show the current version of the repository.
 
@@ -141,6 +150,7 @@ def db_version(engine, abs_path, init_version):
                   "manually."))
 
 
+@removals.remove(message=_removed_msg, version='8.3.0')
 def db_version_control(engine, abs_path, version=None):
     """Mark a database as under this repository's version control.
 

releasenotes/notes/deprecate-sqlalchemy-migrate-6f899935615d6984.yaml

@@ -0,0 +1,8 @@
+---
+deprecations:
+  - |
+    The ``oslo_db.sqlalchemy.migration`` module is deprecated for removal.
+    It only supports ``sqlalchemy-migrate``, which is no longer under active
+    development and has been effectively replaced by ``alembic``. Users of
+    this module should consider switching to ``alembic`` or, if necessary,
+    using ``sqlalchemy-migrate`` directly.