[openstack-dev] [Cinder] [stable] [all] Changing stable policy for drivers

Ben Swartzlander ben at swartzlander.org
Sat Aug 6 21:51:02 UTC 2016

On 08/06/2016 11:31 AM, Sean McGinnis wrote:
> This may mostly be a Cinder concern, but putting it out there to get
> wider input.
> For some time now there has been some debate about moving third party
> drivers in Cinder to be out of tree. I won't go into that too much,
> other than to point out one of the major drivers for this desire that
> was brought up at our recent Cinder midcycle.
> It turned out at least part of the desire to move drivers out of tree
> came down to the difficulty in getting bug fixes out to end users that
> were on older stable versions, whether because that's what their distro
> was still using, or because of some other internal constraint that
> prevented them from upgrading.
> A lot of times what several vendors ended up doing is forking Cinder to
> their own github repo and keeping that in sync with backports, plus
> including driver fixes they needed to get out to their end users. This
> has a few drawbacks:
> 1- this is more work for the vendor to keep this fork up to date
> 2- end users don't necessarily know where to go to find these without
>    calling in to a support desk (that then troubleshoots a known issue
>    and hopefully eventually ends up contacting the folks internally that
>    actually work on Cinder that know it's been fixed and where to get
>    the updates). Generally a bad taste for someone using Cinder and
>    OpenStack.
> 3- Distros that package stable branches aren't able to pick up these
>    changes, even if they are picking up stable branch updates for
>    security fixes
> 4- We end up with a lot of patches proposed against security only stable
>    branches that we need to either leave or abandon, just so a vendor
>    can point end users to the patch to be able to grab the code changes
> Proposed Solution
> -----------------
> So part of our discussion at the midcycle was a desire to open up stable
> restrictions for getting these driver bugfixes backported. At the time,
> we had discussed having new branches created off of the stable branches
> specifically for driver bugfixes. Something like:
> stable/mitaka > stable/mitaka-drivers
> After talking to the infra team, this really did sound like overkill.
> The suggestion was to just change our stable policy in regards to driver
> bugfix backports. No need to create and maintain more branches. No need
> to set up gate jobs and things like that.
> So this is a divergence from our official policy. I want to propose
> we officially make a change to our stable policy to call out that
> drivers bugfixes (NOT new driver features) be allowed at any time.
> If that's not OK with other project teams that support any kind of third
> party drivers, I will just implement this policy specific to Cinder
> unless there is a very strong objection, with good logic behind it, why
> this should not be allowed.
> This would address a lot of the concerns at least within Cinder and
> allow us to better support users stuck on older releases.
> I'm open and welcome to any feedback on this. Unless there are any major
> concerns raised, I will at least instruct any Cinder stable cores to
> start allowing these bugfix patches through past the security only
> phase.

The only issue I see with this modified proposal is that it doesn't 
address the lifetime of the stable branches. If the plan is to use the 
normal stable branch instead of making a special branch, then we also 
need to find a way to keep stable branches around for practically 
forever (way longer than the typical 12 months).

Those of us dealing with bugfix backports for customers inevitably are 
looking at going 3, 4, or 5 releases back with the backports. Therefore 
I'd suggest modifying the policy to keep the stable branches around more 
or less forever, and when it's no longer to run dsvm jobs on them 
(because those jobs WILL eventually break as infra stops maintaining 
support for very old releases) then we simply remove those jobs and rely 
on vendor CI + minimal upstream tests (pep8, unit tests).


> Thanks!
> Sean McGinnis (smcginnis)
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