[openstack-dev] [requirements] History lesson please

Doug Hellmann doug at doughellmann.com
Tue Aug 9 19:09:39 UTC 2016

Excerpts from Hayes, Graham's message of 2016-08-09 18:54:57 +0000:
> On 09/08/2016 19:41, John Dickinson wrote:
> >
> >
> > On 9 Aug 2016, at 11:33, Ian Cordasco wrote:
> >
> >>
> >>
> >> -----Original Message-----
> >> From: John Dickinson <me at not.mn>
> >> Reply: OpenStack Development Mailing List (not for usage questions) <openstack-dev at lists.openstack.org>
> >> Date: August 9, 2016 at 13:17:08
> >> To: OpenStack Development Mailing List <openstack-dev at lists.openstack.org>
> >> Subject:  Re: [openstack-dev] [requirements] History lesson please
> >>
> >>> I'd like to advocate for *not* raising minimum versions very often. Every time some OpenStack
> >>> project raises minimum versions, this change is propagated to all projects, and that
> >>> puts extra burden on anyone who is maintaining packages and dependencies in their own
> >>> deployment. If one project needs a new feature introduced in version 32, but another
> >>> project claims compatibility with >=28, that's ok. There's no need for the second project
> >>> to raise the minimum version when there isn't a conflict. (This is the position I advocated
> >>> for at the Austin summit.)
> >>>
> >>> Yes, I know that currently we don't test every possible version permutation. Yes, I know
> >>> that doing that is hard. I'm not ignoring that.
> >>
> >> Right. So with the current set-up, where these requirements are propogated to every project, how do projects express their own minimum version requirement?
> >>
> >> Let's assume someone is maintaining their own packages and dependencies. If (for example) Glance requires a minimum version of Routes and Nova has a minimum requirement newer than Glance's, they're not coinstallable (which was the original goal of the requirements team). What you're asking for ends up being "Don't rely on new features in a dependency". If OpenStack drops the illusion of coinstallability that ends up being fine. I don't think anyone wants to drop that though.
> >
> > In that case, they are still co-installable, because the nova minimum satisfies both.
> But then packagers are going to have to do the work anyway, as it will
> have in effect raised the minimum version of routes for Glance, and thus
> need a new package.
> It might not make a difference to deployers / packagers who only deploy
> one project from OpenStack, but they are in the minority - having a
> known good minimum for requirements helps deployers who have multiple
> services to deploy.

We've tried to be consistent in telling packagers to use the
versions listed in upper-constraints.txt unless there is an absolute
need to use something else. Those are the versions we test, and
therefore the versions we claim to support right now.


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