[SRU] OpenStack Stable Snapshots

[Corey Bryant]

On Tue, Mar 9, 2021 at 3:06 PM Brian Murray <brian at ubuntu.com> wrote:

> On Mon, Mar 08, 2021 at 11:58:18AM -0500, Corey Bryant wrote:
> > On Mon, Feb 22, 2021 at 5:16 PM Corey Bryant <corey.bryant at canonical.com
> >
> > wrote:
> >
> > > Hello SRU Team,
> > >
> > > I'm writing to discuss delivery of patches from extended maintenance
> > > stable branches as snapshots.
> > >
> > > This would occur during the extended maintenance phase of an upstream
> > > stable branch, which falls between the maintained phase and EOL phase.
> > > I would see this process being similar to the current process that is
> used
> > > to deliver stable point releases, described at:
> > > https://wiki.ubuntu.com/OpenStack/StableReleaseUpdates.
> > >
> > > Snapshots refers to the process by which we currently deliver package
> > > updates during a development release and prior to the final release.
> For
> > > example, nova 3:22.0.1+git2021012713.d92c0740c6-0ubuntu1 in hirsute
> > > contains everything in the upstream master git branch up to commit hash
> > > d92c0740c6.
> > >
> > > == What is Extended Maintenance? ==
> > > First, it's worth understanding what the upstream "Maintained" phase
> is.
> > > During this phase, upstream regularly releases stable point releases
> that
> > > are based on a specific commit (e.g. the latest HEAD commit for the
> > > stable/queens branch at a point in time), and we then package those
> point
> > > releases up in distro.
> > >
> > > Following the "Maintained" phases is the "Extended Maintenance" phase.
> > > During this phase, upstream no longer cuts any stable point releases
> for
> > > that stable branch, however patches continue to be backported to the
> > > branch. This is the phase where we would like to have the ability to
> > > deliver snapshots of stable branches. This would allow us to pick up
> all
> > > stable branch patches since, say, the final point release for
> stable/queens
> > > (bionic). For example, the current version of nova in bionic is
> > > 2:17.0.13-0ubuntu1, and that is based on the final point release for
> > > upstream stable/queens. If we were to do a snapshot today for nova in
> > > bionic, it would be versioned along the lines of
> > > 2:17.0.13+git2021022200.944443a7b0-0ubuntu1.
> > >
> > > More details on upstream maintenance phases can be reviewed at:
> > >
> https://docs.openstack.org/project-team-guide/stable-branches.html#maintenance-phases
> > >
> > > == Advantages of Stable Snapshots ==
> > > * Less overhead for the OpenStack engineering and SRU teams. Currently
> we
> > > have various cherry-picked patches that are dealt with via separate SRU
> > > bugs requiring individual testing.
> > > * As the cherry-pick process is reactive, many of these SRUs tend to be
> > > high impact or critical for users, requiring immediate action from
> these
> > > teams.
> > > * We have a lot of users that are now on, and moving to, bionic
> (queens)
> > > and we would like to be more proactive in fixing bugs for them.
> > > * This would naturally result in a regular cadence along the lines of
> the
> > > monthly stable point release cadence that we currently follow.
> > > * Cherry-picking individual patches can increase regression potential
> for
> > > frequently modified code when they don't apply cleanly.
> > > * All patches that have landed in an extended maintenance branch have
> > > already landed in all ensuing stable branches and master, therefore
> > > negating much of the regression potential mentioned in "Disadvantages"
> > > below.
> > >
> > > == Disadvantages ==
> > > * Upstream stable branches that are in extended maintenance do not
> > > guarantee the same upstream test coverage that supported branches do.
> The
> > > maintenance-phases documentation states "There is no statement about
> the
> > > level of testing and upgrades from Extended Maintenance are not
> supported
> > > within the Community."
> > >
> > > == What Ubuntu Releases would this affect? ==
> > > Stable snapshots would only be needed for Ubuntu LTS releases (Upstream
> > > "Maintained" period is 18 months for stable branches). Currently this
> would
> > > only be applicable to Ubuntu 18.04 as bionic is the only LTS with a
> > > corresponding upstream stable branch that's in extended maintenance.
> > >
> > > == How many patches are we talking about? ==
> > > For a sampling of stable/queens, new snapshots would pick up this many
> > > patches:
> > >
> > > nova: 337
> > > neutron: 106
> > > heat: 47
> > > cinder: 21
> > > glance: 11
> > > designate: 11
> > > swift: 10
> > > horizon: 8
> > > keystone: 7
> > >
> > > A few of those look daunting, yes, but perhaps that depends on how you
> > > look at it. Also please keep in mind, queens has been in extended
> > > maintenance since October of 2019 so this would be quite the one-time
> > > waterfall for bionic. In the future we'd pick up fewer patches at a
> time at
> > > a regular cadence.
> > >
> > > Thanks for taking the time to read this. Please let me know if you have
> > > any opinions or questions about this approach.
> > >
> > > Corey
> > >
> >
> > Hello SRU Team,
> >
> > I wanted to see if I could revive this topic and discuss the possibility
> of
> > moving forward with stable snapshots as described in this thread.
> >
> > Would it make sense to add this to a meeting agenda or is the mailing
> list
> > a good place to discuss?
>
> The Ubuntu SRU team does have a monthly meeting (conducted via Google
> Meet or whatever it is called now) and the next one is scheduled for
> Thursday, March 18th. Unfortunately I won't be able to attend that
> meeting but perhaps the other SRU team members can invite you so it can
> be discussed.
>
>
Thanks, that would be great.

Corey
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