When running unit tests in nova, we see the following error message quite regularly:
2021-08-17 11:54:58.368 27961 ERROR stevedore.extension [req-ac3ac729-e3f6-4977-95ac-f3a2b8bb7457 fake_user 6a6a9c9eee154e9cb8cec487b98d36ab - - -] Could not load 'oslo_cache.memcache_pool': No module named 'memcache': ModuleNotFoundError: No module named 'memcache'
2021-08-17 11:54:58.375 27959 ERROR stevedore.extension [req-3c345bf7-7af2-43b7-aa63-fe6274991b2e fake_user 6a6a9c9eee154e9cb8cec487b98d36ab - - -] Could not load 'oslo_cache.memcache_pool': No module named 'memcache': ModuleNotFoundError: No module named 'memcache'
2021-08-17 11:54:58.393 27962 ERROR stevedore.extension [req-8f167a6a-ca66-4386-9dad-78ae4e63173a fake_user 6a6a9c9eee154e9cb8cec487b98d36ab - - -] Could not load 'oslo_cache.memcache_pool': No module named 'memcache': ModuleNotFoundError: No module named 'memcache'
2021-08-17 11:54:58.545 27960 ERROR stevedore.extension [req-64210d11-2585-477c-8dac-07bd12ba72c2 fake_user 6a6a9c9eee154e9cb8cec487b98d36ab - - -] Could not load 'oslo_cache.memcache_pool': No module named 'memcache': ModuleNotFoundError: No module named 'memcache'
By stopping the process at the right time, we see the following exception:
File "/opt/stack/nova/tests/unit/test_availability_zones.py", line 34, in <module>
class AvailabilityZoneTestCases(test.TestCase):
File "/opt/stack/nova/tests/unit/test_availability_zones.py", line 254, in AvailabilityZoneTestCases
@mock.patch.object(az._get_cache(), 'get')
File "/opt/stack/nova/availability_zones.py", line 36, in _get_cache
MC = cache_utils.get_client(expiration_time=AZ_CACHE_SECONDS)
File "/opt/stack/nova/cache_utils.py", line 58, in get_client
backend='oslo_cache.dict'))
File "/opt/stack/nova/cache_utils.py", line 96, in _get_custom_cache_region
region.configure(backend, **region_params)
File "/opt/stack/.tox/py36/lib/python3.6/site-packages/dogpile/cache/region.py", line 480, in configure
backend_cls = _backend_loader.load(backend)
File "/opt/stack/.tox/py36/lib/python3.6/site-packages/dogpile/util/langhelpers.py", line 47, in load
self._mgr = stevedore.ExtensionManager(self.group)
File "/opt/stack/.tox/py36/lib/python3.6/site-packages/stevedore/extension.py", line 136, in __init__
verify_requirements)
File "/opt/stack/.tox/py36/lib/python3.6/site-packages/stevedore/extension.py", line 243, in _load_plugins
exc_info=LOG.isEnabledFor(logging.DEBUG))
Message: 'Could not load %r: %s'
Arguments: ('oslo_cache.memcache_pool', ModuleNotFoundError("No module named 'memcache'",))
I've yet to figure out how to silence these errors or whether it's actually nova that needs to change something, but I suspect we might need configure stevedore slightly differently.
Leaving this here so I remember to investigate in the future.
