Re: [PATCH] ci: bump debian-11 job to debian-12

[Jeff King <peff@peff.net>]

On Mon, Sep 07, 2026 at 08:03:34AM +0200, Patrick Steinhardt wrote:

> > +      # Supported until 2028-06-30.
> > +      - jobname: debian-12
> > +        image: debian:12
> >    artifacts:
> >      paths:
> >        - t/failed-test-artifacts
> 
> The changes look good, but I wonder whether we want to swap to the
> "oldstable" tag instead. That points to debian-12, too, and might result
> in less churn going forward.

I was all ready to agree and propose a patch, but I think it might be
more complicated. The "old" flags flip when a new stable version is
released, but what we really care about is things leaving LTS. And the
two are not really aligned.

So if we wanted the oldest supported Debian release, that would have
been "oldoldstable" (debian-11) until August 31st of this year. But
after that, we want "oldstable" (debian-12), which is now the oldest
thing under LTS. And that will be true until probably next summer, when
debian-14 is released, at which point we'd want to stay on it by
switching to "oldoldstable" again for another year.

The offset comes from the fact that Debian releases approximately every
2 years, but with a 5-year LTS, and they never align.

If we track oldstable, then every other year we're not using the oldest
supported release (because the prior release is still in LTS). Or we
track oldoldstable, which means every other year we're using a release
that's no longer supported. Or we flip-flop between them once a year,
when oldoldstable goes out of support.

Which makes me inclined to just keep the current scheme: use the numeric
codes and just bump them every 2 years or so when they go out of
support. And we can even put it off until the out-of-support release
starts causing problems like it did here.

-Peff