Open Stack

On 2013-12-03 15:56, Sean Dague wrote:
> This cinder patch - https://review.openstack.org/#/c/48935/
> 
> Is blocked on failing upgrade because the updated oslo lockutils won't
> function until there is a specific configuration variable added to the
> cinder.conf.
> 
> That work around is proposed here -
> https://review.openstack.org/#/c/52070/3
> 
> However I think this is exactly the kind of forward breaks that we want
> to prevent with grenade, as cinder failing to function after a rolling
> upgrade because a config item wasn't added is exactly the kind of pain
> we are trying to prevent happening to ops.
> 
> So the question is, how is this done correctly so that a default can be
> set in the cinder code for this value, and it not require a config
> change to work?

I don't know that I have a good answer on how to handle this, but for 
context this change is the result of a nasty bug in lockutils that meant 
external locks were doing nothing if lock_path wasn't set.  Basically 
it's something we should never have allowed in the first place.

As far as setting this in code, it's important that all of the processes 
for a service are using the same value to avoid the same bad situation 
we were in before.  For tests, we have a lockutils wrapper 
(https://github.com/openstack/oslo-incubator/blob/master/openstack/common/lockutils.py#L282) that sets an environment variable to address this, but that only works if all of the processes are going to be spawned from within the same wrapper, and I'm not sure how secure that is for production deployments since it puts all of the lock files in a temporary directory.

-Ben