Cleanup DB schema after Mitaka

This commit removes tables and columns that we've stopped referencing in
Mitaka. Due to rolling upgrades guidelines we were unable to remove them
immediately, so let's do that in early Newton.

Change-Id: Iacd950d335e1142585c9c51f185fc12e7e0fd911

cinder/db/sqlalchemy/migrate_repo/versions/073_drop_available_versions_and_iscsi_targets.py

@@ -0,0 +1,25 @@
+#    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 import MetaData, Table
+
+
+def upgrade(migrate_engine):
+    meta = MetaData()
+    meta.bind = migrate_engine
+
+    services = Table('services', meta, autoload=True)
+    services.c.rpc_available_version.drop()
+    services.c.object_available_version.drop()
+
+    iscsi_targets = Table('iscsi_targets', meta, autoload=True)
+    iscsi_targets.drop()

cinder/db/sqlalchemy/models.py

@@ -75,10 +75,6 @@ class Service(BASE, CinderBase):
     rpc_current_version = Column(String(36))
     object_current_version = Column(String(36))
 
-    # FIXME(dulek): In M we've removed rpc_available_version and
-    # object_available_version from the model. We need to merge a DB migration
-    # that actually drops these columns from the DB in early Newton.
-
     # replication_status can be: enabled, disabled, not-capable, error,
     # failed-over or not-configured
     replication_status = Column(String(255), default="not-capable")

cinder/tests/unit/test_migrations.py

@@ -110,6 +110,9 @@ class MigrationsMixin(test_migrations.WalkVersionsMixin):
             # is performed with the same restrictions as column addition, which
             # we of course allow.
             66,
+            # NOTE(dulek): 73 drops tables and columns we've stopped using a
+            # release ago.
+            73,
         ]
 
         # NOTE(dulek): We only started requiring things be additive in