make datastore_version_id required

The datastore addition didn't migrate existing instances,
which causes existing installations to blow up after upgrading.
This commit addresses that by inserting best-guess dummy data
into the db.  Operators will need to clean up the values to match
their actual usage.

Change-Id: I7ae064cea9b654a4501b91877b779fb4073623af
Closes-Bug: #1259642

trove/db/sqlalchemy/migrate_repo/versions/019_datastore_fix.py

@@ -0,0 +1,72 @@
+# Copyright 2012 OpenStack Foundation
+#
+#    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.schema import MetaData
+from sqlalchemy.sql.expression import select
+from trove.common import cfg
+from trove.datastore.models import DBDatastore
+from trove.datastore.models import DBDatastoreVersion
+from trove.db.sqlalchemy import session
+from trove.db.sqlalchemy.migrate_repo.schema import Table
+from trove.instance.models import DBInstance
+
+CONF = cfg.CONF
+meta = MetaData()
+
+
+def upgrade(migrate_engine):
+    meta.bind = migrate_engine
+
+    instance_table = Table('instances', meta, autoload=True)
+
+    session.configure_db(CONF)
+
+    instances = DBInstance.find_all(datastore_version_id=None)
+    if instances.count() > 0:
+        datastore = DBDatastore.get_by(manager="mysql")
+        datastore = datastore or DBDatastore.create(
+            name="Legacy MySQL",
+            manager="mysql",
+        )
+
+        image_table = Table('service_images', meta, autoload=True)
+        image = select(
+            columns=["id", "image_id", "service_name"],
+            from_obj=image_table,
+            whereclause="service_name='mysql'",
+            limit=1
+        ).execute().fetchone()
+
+        image_id = "00000000-0000-0000-0000-000000000000"
+        if image:
+            image_id = image.image_id
+
+        version = DBDatastoreVersion.create(
+            datastore_id=datastore.id,
+            name="Unknown Legacy Version",
+            image_id=image_id,
+            active=False,
+        )
+
+        for instance in instances:
+            instance.update_db(datastore_version_id=version.id)
+
+    instance_table.c.datastore_version_id.alter(nullable=False)
+
+
+def downgrade(migrate_engine):
+    meta.bind = migrate_engine
+
+    instance_table = Table('instances', meta, autoload=True)
+    instance_table.c.datastore_version_id.alter(nullable=True)