No _writer_maker attribute on enginefacade.writer

[Julien Danjou]

I've tried using it but it fails with the following traceback. This is either a bug or a "documentation problem" that does not enable me to use it correctly. ;)

gnocchi.tests.test_indexer.TestIndexerDriver.test_update_resource_end_timestamp
-------------------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "gnocchi/tests/base.py", line 50, in skip_if_not_implemented
        return func(*args, **kwargs)
      File "gnocchi/tests/base.py", line 361, in setUp
        self.index.upgrade(nocreate=True)
      File "/Users/jd/Source/gnocchi/.tox/py27-postgresql-swift/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 664, in wrapper
        with self._transaction_scope(context):
      File "/usr/local/Cellar/python/2.7.10_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
        return self.gen.next()
      File "/Users/jd/Source/gnocchi/.tox/py27-postgresql-swift/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 714, in _transaction_scope
        savepoint=self._savepoint) as resource:
      File "/usr/local/Cellar/python/2.7.10_2/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
        return self.gen.next()
      File "/Users/jd/Source/gnocchi/.tox/py27-postgresql-swift/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 484, in _session
        bind=self.connection, mode=self.mode)
      File "/Users/jd/Source/gnocchi/.tox/py27-postgresql-swift/lib/python2.7/site-packages/oslo_db/sqlalchemy/enginefacade.py", line 279, in _create_session
        return self._writer_maker(**kw)
    AttributeError: '_TransactionFactory' object has no attribute '_writer_maker'

[Mike Bayer (zzzeek)]

hi julien -

can you show me the setup code for this? if you're on enginefacade then everything has to be within a context. this is definitely bad error reporting on its part but it seems maybe you aren't in a context block/decorator here?

[Julien Danjou (jdanjou)]

Hi Mike!

So I've just sent the patch at https://review.openstack.org/#/c/204669/1/gnocchi/indexer/sqlalchemy.py

I've copied what I saw in the example at http://docs.openstack.org/developer/oslo.db/usage.html#session-handling, I just skipped the custom MyContext class as I don't need anything fancy.

[Yongli He (yongli-he)]

Inel PCI CI also hit this bug:
here is a log link:
http://52.27.155.124/243557/2/screen-logs/n-api.log.gz

and major port of this log:

2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions return IMPL.network_get_all(context, project_only)
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions File "/opt/stack/nova/nova/db/sqlalchemy/api.py", line 204, in wrapper
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions return f(*args, **kwargs)
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions File "/opt/stack/nova/nova/db/sqlalchemy/api.py", line 2920, in network_get_all
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions project_only=project_only).all()
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions File "/opt/stack/nova/nova/db/sqlalchemy/api.py", line 266, in model_query
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions session = get_session(use_slave=use_slave)
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions File "/opt/stack/nova/nova/db/sqlalchemy/api.py", line 172, in get_session
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions use_slave=use_slave, **kwargs)
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 977, in get_session
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions return self._factory._writer_maker(**kwargs)
2015-11-11 20:49:17.715 106701 ERROR nova.api.openstack.extensions AttributeError: '_TransactionFactory' object has no attribute '_writer_maker'

[Mike Bayer (zzzeek)]

this issue has to do with using enginefacade in a non-initialized state. But the bug here is a gnochhi issue AFAICT and the patch I've put up to correct it can be seen at https://review.openstack.org/#/c/204669/. if we are just looking for a nicer error message in oslo, that's something else but it's misleading IMO for this bug to be assigned to oslo.db.

[Mike Bayer (zzzeek)]

please post the Nova stack trace here as a new issue on Nova, assuming this has to do with the patches for https://blueprints.launchpad.net/nova/+spec/new-oslodb-enginefacade the issue would exist within the realm of the enginefacade being used outside of the correct context.

[Davanum Srinivas (DIMS) (dims-v)]

Mike, please see https://bugs.launchpad.net/oslo.db/+bug/1515326

[Mike Bayer (zzzeek)]

this was fixed in https://review.openstack.org/#/c/205646/