It seems that it does not work currently:
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy [-] Failed to record event: When initializing mapper Mapper|Meter|meter, expression 'Sample' failed to locate a name ("name 'Sample' is not defined"). If this is a class name, consider adding this relationship() to the <class 'ceilometer.storage.sqlalchemy.models.Meter'> class after both dependent classes have been defined.
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy Traceback (most recent call last):
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/opt/stack/new/panko/panko/event/storage/impl_sqlalchemy.py", line 178, in record_events
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy event_model.event_type, session=session)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/opt/stack/new/panko/panko/event/storage/impl_sqlalchemy.py", line 156, in _get_or_create_event_type
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy et = session.query(models.EventType).filter(
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1260, in query
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy return self._query_cls(entities, self, **kwargs)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 110, in __init__
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self._set_entities(entities)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 120, in _set_entities
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self._set_entity_selectables(self._entities)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 150, in _set_entity_selectables
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy ent.setup_entity(*d[entity])
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line 3446, in setup_entity
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self._with_polymorphic = ext_info.with_polymorphic_mappers
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 754, in __get__
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy obj.__dict__[self.__name__] = result = self.fget(obj)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1893, in _with_polymorphic_mappers
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy configure_mappers()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2770, in configure_mappers
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy mapper._post_configure_properties()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 1710, in _post_configure_properties
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy prop.init()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/interfaces.py", line 183, in init
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self.do_init()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/relationships.py", line 1628, in do_init
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self._process_dependent_arguments()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/relationships.py", line 1685, in _process_dependent_arguments
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy self.target = self.mapper.mapped_table
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 754, in __get__
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy obj.__dict__[self.__name__] = result = self.fget(obj)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/orm/relationships.py", line 1601, in mapper
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy argument = self.argument()
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/ext/declarative/clsregistry.py", line 293, in __call__
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy (self.prop.parent, self.arg, n.args[0], self.cls)
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy InvalidRequestError: When initializing mapper Mapper|Meter|meter, expression 'Sample' failed to locate a name ("name 'Sample' is not defined"). If this is a class name, consider adding this relationship() to the <class 'ceilometer.storage.sqlalchemy.models.Meter'> class after both dependent classes have been defined.
2016-09-08 18:07:14.043 29687 ERROR panko.event.storage.impl_sqlalchemy
Since we don't have much functional test in the gate, we missed it probably.
I wonder if it's not only a problem when using the same database than Ceilometer?