We have seen this again during this test run: https://solutions.qa.canonical.com/testruns/testRun/d0e3e447-d9e5-4651-827c-593e433eae21

Crashdump here: https://oil-jenkins.canonical.com/artifacts/d0e3e447-d9e5-4651-827c-593e433eae21/generated/generated/openstack/juju-crashdump-openstack-2021-06-06-18.04.08.tar.gz

designate_1/var/log/designate/designate-mdns.log:

2021-06-06 15:11:18.613 56988 CRITICAL designate [-] Unhandled error: oslo_db.exception.CantStartEngineError: No sql_connection parameter is established
2021-06-06 15:11:18.613 56988 ERROR designate Traceback (most recent call last):
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/bin/designate-mdns", line 10, in <module>
2021-06-06 15:11:18.613 56988 ERROR designate     sys.exit(main())
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/cmd/mdns.py", line 41, in main
2021-06-06 15:11:18.613 56988 ERROR designate     server = mdns_service.Service()
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/mdns/service.py", line 47, in __init__
2021-06-06 15:11:18.613 56988 ERROR designate     self.dns_application, self.tg,
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/utils.py", line 256, in wrapper
2021-06-06 15:11:18.613 56988 ERROR designate     cache.append(function(cls_instance))
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/mdns/service.py", line 78, in dns_application
2021-06-06 15:11:18.613 56988 ERROR designate     application = handler.RequestHandler(self.storage, self.tg)
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/mdns/service.py", line 65, in storage
2021-06-06 15:11:18.613 56988 ERROR designate     CONF['service:mdns'].storage_driver
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/storage/__init__.py", line 36, in get_storage
2021-06-06 15:11:18.613 56988 ERROR designate     return cls()
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/storage/impl_sqlalchemy/__init__.py", line 40, in __init__
2021-06-06 15:11:18.613 56988 ERROR designate     super(SQLAlchemyStorage, self).__init__()
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/sqlalchemy/base.py", line 72, in __init__
2021-06-06 15:11:18.613 56988 ERROR designate     self.engine = session.get_engine(self.get_name())
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/sqlalchemy/session.py", line 47, in get_engine
2021-06-06 15:11:18.613 56988 ERROR designate     facade = _create_facade_lazily(cfg_group)
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/designate/sqlalchemy/session.py", line 40, in _create_facade_lazily
2021-06-06 15:11:18.613 56988 ERROR designate     **conf
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 1295, in __init__
2021-06-06 15:11:18.613 56988 ERROR designate     slave_connection=slave_connection)
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 510, in _start
2021-06-06 15:11:18.613 56988 ERROR designate     engine_args, maker_args)
2021-06-06 15:11:18.613 56988 ERROR designate   File "/usr/lib/python3/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 532, in _setup_for_connection
2021-06-06 15:11:18.613 56988 ERROR designate     "No sql_connection parameter is established")
2021-06-06 15:11:18.613 56988 ERROR designate oslo_db.exception.CantStartEngineError: No sql_connection parameter is established
2021-06-06 15:11:18.613 56988 ERROR designate