db migration (agents constraint) fails when using ryu plugin

[Yoshihiro Kaneko]

Ryu plugin does not support agent extension yet.
Therefore, 511471cc46b_agent_ext_model_supp.py does not contain ryu plugin, and agents table is not created.
However, 1fcfc149aca4_agents_unique_by_type_and_host.py does not consider this case.
I think that migration_for_plugins of 1fcfc149aca4 should be the same as 511471cc46b's.

2013-12-12 01:08:44 INFO [alembic.migration] Running upgrade e197124d4b9 -> 1fcfc149aca4, Add a unique constraint on (agent_type, host) columns to prevent a race
2013-12-12 01:08:44 condition when an agent entry is 'upserted'.
2013-12-12 01:08:44 Traceback (most recent call last):
2013-12-12 01:08:44 File "/usr/local/bin/neutron-db-manage", line 10, in <module>
2013-12-12 01:08:44 sys.exit(main())
2013-12-12 01:08:44 File "/opt/stack/neutron/neutron/db/migration/cli.py", line 143, in main
2013-12-12 01:08:44 CONF.command.func(config, CONF.command.name)
2013-12-12 01:08:44 File "/opt/stack/neutron/neutron/db/migration/cli.py", line 80, in do_upgrade_downgrade
2013-12-12 01:08:44 do_alembic_command(config, cmd, revision, sql=CONF.command.sql)
2013-12-12 01:08:44 File "/opt/stack/neutron/neutron/db/migration/cli.py", line 59, in do_alembic_command
2013-12-12 01:08:44 getattr(alembic_command, cmd)(config, *args, **kwargs)
2013-12-12 01:08:44 File "/usr/local/lib/python2.7/dist-packages/alembic/command.py", line 124, in upgrade
2013-12-12 01:08:44 script.run_env()
2013-12-12 01:08:44 File "/usr/local/lib/python2.7/dist-packages/alembic/script.py", line 193, in run_env
2013-12-12 01:08:44 util.load_python_file(self.dir, 'env.py')
2013-12-12 01:08:44 File "/usr/local/lib/python2.7/dist-packages/alembic/util.py", line 177, in load_python_file
2013-12-12 01:08:44 module = load_module(module_id, path)
2013-12-12 01:08:44 File "/usr/local/lib/python2.7/dist-packages/alembic/compat.py", line 39, in load_module
2013-12-12 01:08:44 return imp.load_source(module_id, path, fp)
2013-12-12 01:08:44 File "/opt/stack/neutron/neutron/db/migration/alembic_migrations/env.py", line 105, in <module>
2013-12-12 01:08:44 run_migrations_online()
2013-12-12 01:08:44 File "/opt/stack/neutron/neutron/db/migration/alembic_migrations/env.py", line 89, in run_migrations_online
2013-12-12 01:08:44 options=build_options())
2013-12-12 01:08:44 File "<string>", line 7, in run_migrations
2013-12-12 01:08:44 File "/usr/local/lib/python2.7/dist-packages/alembic/environment.py", line 652, in run_migrations
2013-12-12 01:08:45 self.get_context().run_migrations(**kw)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/alembic/migration.py", line 224, in run_migrations
2013-12-12 01:08:45 change(**kw)
2013-12-12 01:08:45 File "/opt/stack/neutron/neutron/db/migration/alembic_migrations/versions/1fcfc149aca4_agents_unique_by_type_and_host.py", line 50, in upgrade
2013-12-12 01:08:45 local_cols=['agent_type', 'host']
2013-12-12 01:08:45 File "<string>", line 7, in create_unique_constraint
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/alembic/operations.py", line 539, in create_unique_constraint
2013-12-12 01:08:45 schema=schema, **kw)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/alembic/ddl/impl.py", line 135, in add_constraint
2013-12-12 01:08:45 self._exec(schema.AddConstraint(const))
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/alembic/ddl/impl.py", line 76, in _exec
2013-12-12 01:08:45 conn.execute(construct, *multiparams, **params)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1449, in execute
2013-12-12 01:08:45 params)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1542, in _execute_ddl
2013-12-12 01:08:45 compiled
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1698, in _execute_context
2013-12-12 01:08:45 context)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1691, in _execute_context
2013-12-12 01:08:45 context)
2013-12-12 01:08:45 File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 331, in do_execute
2013-12-12 01:08:45 cursor.execute(statement, parameters)
2013-12-12 01:08:45 File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 174, in execute
2013-12-12 01:08:45 self.errorhandler(self, exc, value)
2013-12-12 01:08:45 File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 36, in defaulterrorhandler
2013-12-12 01:08:45 raise errorclass, errorvalue
2013-12-12 01:08:45 sqlalchemy.exc.ProgrammingError: (ProgrammingError) (1146, "Table 'ovs_neutron.agents' doesn't exist") 'ALTER TABLE agents ADD CONSTRAINT uniq_agents0agent_type0host UNIQUE (agent_type, host)' ()

[Edgar Magana (emagana)]

This is the same bug that the one above but for a different plugin:
https://bugs.launchpad.net/neutron/+bug/1260232

Let's fix this in only one commit. I can take it or you can, just let me know.

[Yoshihiro Kaneko (ykaneko0929)]

Change I7915ef8d seems to fix these problems.
  https://review.openstack.org/#/c/61663/

[Akihiro Motoki (amotoki)]

This is the same issue as bug 1254246.