broken upgrade path q->r requirement for oslo.db

[Tobias Urdin]

Nova is using async_ introduced in oslo.db 4.40.0 but requirements.txt says oslo.db>=4.27.0
https://github.com/openstack/oslo.db/commit/df6bf3401266f42271627c1e408f87c71a06cef7

So if you still have an old oslo.db version from queens that satisfies that requirement services will fail with below:

2018-09-19 16:56:35.965 136178 ERROR oslo_service.service Traceback (most recent call last):
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_service/service.py", line 729, in run_service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service service.start()
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/service.py", line 180, in start
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service self.manager.pre_start_hook()
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 1249, in pre_start_hook
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service startup=True)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 7757, in update_available_resource
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service startup=startup)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 7788, in _get_compute_nodes_in_db
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service use_slave=use_slave)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_versionedobjects/base.py", line 177, in wrapper
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service args, kwargs)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/conductor/rpcapi.py", line 241, in object_class_action_versions
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service args=args, kwargs=kwargs)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/client.py", line 179, in call
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service retry=self.retry)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_messaging/transport.py", line 133, in _send
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service retry=retry)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 584, in send
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service call_monitor_timeout, retry=retry)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_messaging/_drivers/amqpdriver.py", line 575, in _send
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service raise result
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service AttributeError: '_TransactionContextManager' object has no attribute 'async_'
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service Traceback (most recent call last):
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/conductor/manager.py", line 126, in _object_dispatch
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service return getattr(target, method)(*args, **kwargs)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/oslo_versionedobjects/base.py", line 184, in wrapper
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service result = fn(cls, context, *args, **kwargs)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/objects/compute_node.py", line 437, in get_all_by_host
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service use_slave=use_slave)
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service File "/usr/lib/python2.7/site-packages/nova/db/sqlalchemy/api.py", line 205, in wrapper
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service reader_mode = get_context_manager(context).async_
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service
2018-09-19 16:56:35.965 136178 ERROR oslo_service.service AttributeError: '_TransactionContextManager' object has no attribute 'async_'

[Corey Bryant (corey.bryant)]

Thanks very much for reporting this Tobias. I will have a fix coming for the Ubuntu package. We use apt dist-upgrade in our upgrade tests which won't uncover this.

[Launchpad Janitor (janitor)]

This bug was fixed in the package nova - 2:18.0.0-0ubuntu5

---------------
nova (2:18.0.0-0ubuntu5) cosmic; urgency=medium

  * d/control: Set min python-oslo.db to rocky version (4.40.0) as
    requirements.txt min version is too low (LP: #1793353).

 -- Corey Bryant <email address hidden> Thu, 20 Sep 2018 11:26:53 +0200

[Matt Riedemann (mriedem)]

This was already fixed in nova, I need to duplicate the bug for that.

[Matt Riedemann (mriedem)]

This was the nova fix: https://review.openstack.org/#/c/597421/

[Corey Bryant (corey.bryant)]

This bug was fixed in the package nova - 2:18.0.0-0ubuntu5~cloud0
---------------

 nova (2:18.0.0-0ubuntu5~cloud0) bionic-rocky; urgency=medium
 .
   * New update for the Ubuntu Cloud Archive.
 .
 nova (2:18.0.0-0ubuntu5) cosmic; urgency=medium
 .
   * d/control: Set min python-oslo.db to rocky version (4.40.0) as
     requirements.txt min version is too low (LP: #1793353).