[openstack-dev] [goals][python3] mixed versions?

Doug Hellmann doug at doughellmann.com
Fri Sep 14 02:14:49 UTC 2018

Excerpts from Mathieu Gagné's message of 2018-09-13 20:09:12 -0400:
> On Thu, Sep 13, 2018 at 7:41 PM, Doug Hellmann <doug at doughellmann.com> wrote:
> > Excerpts from Mathieu Gagné's message of 2018-09-13 14:12:56 -0400:
> >> On Wed, Sep 12, 2018 at 2:04 PM, Doug Hellmann <doug at doughellmann.com> wrote:
> >> >
> >> > IIRC, we also talked about not supporting multiple versions of
> >> > python on a given node, so all of the services on a node would need
> >> > to be upgraded together.
> >> >
> >>
> >> Will services support both versions at some point for the same
> >> OpenStack release? Or is it already the case?
> >>
> >> I would like to avoid having to upgrade Nova, Neutron and Ceilometer
> >> at the same time since all end up running on a compute node and
> >> sharing the same python version.
> >
> > We need to differentiate between what the upstream community supports
> > and what distros support. In the meeting in Vancouver, we said that
> > the community would support upgrading all of the services on a
> > single node together. Distros may choose to support more complex
> > configurations if they choose, and I'm sure patches related to any
> > bugs would be welcome.
> We maintain and build our own packages with virtualenv. We aren't
> bound to distribution packages.

OK, I should rephrase then. I'm talking about the limits on the
tests that I think are useful and reasonable to run upstream and
for the community to support.

> > But I don't think we can ask the community
> > to support the infinite number of variations that would occur if
> > we said we would test upgrading some services independently of
> > others (unless I'm mistaken, we don't even do that for services
> > all using the same version of python 2, today).
> This contradicts what I heard in fishbowl sessions from core reviewers
> and read on IRC.
> People were under the false impression that you need to upgrade
> OpenStack in lock steps when in fact, it has never been the case.
> You should be able to upgrade services individually.
> Has it changed since?

I know that some deployments do upgrade components separately, and
it works in some configurations.  All we talked about in Vancouver
was how we would test upgrading python 2 to python 3, and given
that the community has never, as far as I know, run upgrade tests
in CI that staggered the upgrades of components on a given node,
there seemed no reason to add those tests just for the python 2 to
3 case.

Perhaps someone on the QA team can correct me if I'm wrong about the
history there.


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