Comment 4 for bug 1775553

One possibly related observation:

tempest.api.object_storage.test_account_services.AccountTest uses two accounts, but with the default settings "tempest account-generator" only generates one account, causing the tempest run to fail:

setUpClass (tempest.api.object_storage.test_account_services.AccountTest)
-------------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "tempest/test.py", line 172, in setUpClass
        six.reraise(etype, value, trace)
      File "tempest/test.py", line 157, in setUpClass
        cls.setup_credentials()
      File "tempest/api/object_storage/test_account_services.py", line 38, in setup_credentials
        super(AccountTest, cls).setup_credentials()
      File "tempest/api/object_storage/base.py", line 77, in setup_credentials
        super(BaseObjectTest, cls).setup_credentials()
      File "tempest/test.py", line 401, in setup_credentials
        force_new=True)
      File "tempest/test.py", line 670, in get_client_manager
        creds = cred_provider.get_creds_by_roles(**params)
      File "tempest/lib/common/preprov_creds.py", line 315, in get_creds_by_roles
        net_creds = self._get_creds(roles=roles)
      File "tempest/lib/common/preprov_creds.py", line 248, in _get_creds
        free_hash = self._get_free_hash(useable_hashes)
      File "/opt/stack/tempest/.tox/tempest/local/lib/python2.7/site-packages/oslo_concurrency/lockutils.py", line 274, in inner
        return f(*args, **kwargs)
      File "tempest/lib/common/preprov_creds.py", line 203, in _get_free_hash
        raise lib_exc.InvalidCredentials(msg)
    tempest.lib.exceptions.InvalidCredentials: Invalid Credentials
    Details: Insufficient number of users provided. AccountTest have allocated all the credentials for this allocation request

When running the account-generator with "-r 2", a serial tempest run succeeds, while setting "--concurrency 2" again leads to failures. This doesn't seem to be visible in gate where we run with "-r 8" and don't have enough different object_storage test classes to exhaust those eight accounts.