[openstack-dev] [cinder] [nova] locking concern with os-brick

Joshua Harlow harlowja at fastmail.com
Sun Aug 14 16:40:41 UTC 2016


Clint Byrum wrote:
> Excerpts from Joshua Harlow's message of 2016-08-13 20:04:13 -0700:
>> The larger issue here IMHO is that there is now a<between-project>  API
>> around locking that might be better suited targeting an actual lock
>> management system (say redis or zookeeper or etcd or ...).
>
> The more I look at this, the more I think this is just evidence that
> the compute node itself needs to be an API unto itself. Whether it's
> Neutron agents, cinder volumes, or what, nova-compute has a bunch of
> under-the-covers interactions with things like this. It would make more
> sense to put that into its own implementation behind a real public API
> than what we have now: processes that just magically expect to be run
> together with shared filesystems, lock dirs, network interfaces, etc.
>
> That would also go a long way to being able to treat the other components
> more like microservices.
>

I very much agree, the amount of interactions 'under-the-covers' makes 
it really hard to do many things (including understanding what those 
interactions even are). For example, how does someone even install 
'os-brick' at this point, if it requires as a prerequisite that cinder 
and nova-compute be pre-setup with the <same lock dir>? Sucks I guess 
for people/operators/anyone using both components, that are already 
running those with different lock directories...

IMHO the amount of time done 'hacking in solutions' like a shared lock 
directory (or moving both projects to share the same configuration 
somehow) would be better spent on an actual locking solution/service and 
thinking about microservices and ... but meh, what can u do...

-Josh



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