Open Stack

Dear OpenStackers,

earlier this year Ubuntu released their current LTS version 18.04
codenamed "Bionic Beaver" and we are now facing the task to migrate
our devstack-based jobs to run on Bionic instead of the previous LTS
version 16.04 "Xenial Xerus".

The last time this has happened two years ago (migration from 14.04 to
16.04) and at that time it seems the migration was mostly driven by
the Infra team (see [1]), mostly because all of the job configuration
was still centrally hosted in a single repository
(openstack-infra/project-config). In the meantime, however, our CI
setup has been updated to use Zuul v3 and one of the new features that
come with this development is the introduction of per-project job
definitions.

So this new flexibility requires us to make a choice between the two
possible options we have for migrating jobs now:

    1) Change the "devstack" base job to run on Bionic instances
instead of Xenial instances
    2) Create new "devstack-bionic" and "tempest-full-bionic" base
jobs and migrate projects piecewise

Choosing option 1) would cause all projects that base their own jobs
on this job (possibly indirectly by e.g. being based on the
"tempest-full" job) switch automatically. So there would be the
possibility that some jobs would break and require to be fixed before
patches could be merged again in the affected project(s). To
accomodate those risks, QA team can give some time to projects to test
their jobs on Bionic with WIP patches (QA can provide Bionic base job
as WIP patch). This option does not require any pre/post migration
changes on project's jobs.

Choosing option 2) would avoid this by letting projects switch at
their own pace, but create the risk that some projects would never
migrate. It would also make further migrations, like the one expected
to happen when 20.04 is released, either having to follow the same
scheme or re-introduce the unversioned base job. Other point to note
down with this option is,
   - project job definitions need to change their parent job from
"devstack" -> "devstack-bionic" or "tempest-full" ->
"tempest-full-bionic"
 - QA needs to maintain existing jobs ("devstack", "tempest-full") and
bionic version jobs ("devstack-bionic", "tempest-full-bionic")

In order to prepare the decision, we have created a set of patches
that test the Bionic
jobs, you can find them under the common topic "devstack-bionic" [2].
There is also an
etherpad to give a summarized view of the results of these tests [3].

Please respond to this mail if you want to promote either of the above
options or
maybe want to propose an even better solution. You can also find us
for discussion
in the #openstack-qa IRC channel on freenode.

Infra team has tried both approaches during precise->trusty &
trusty->xenial migration[4].

Note that this mailing-list itself will soon be migrated, too, so if
you haven't subscribed
to the new list yet, this is a good time to act and avoid missing the
best parts [5].

Yours,
Jens (frickler at IRC)


[1] http://lists.openstack.org/pipermail/openstack-dev/2016-November/106906.html
[2] https://review.openstack.org/#/q/topic:devstack-bionic
[3] https://etherpad.openstack.org/p/devstack-bionic
[4] http://eavesdrop.openstack.org/irclogs/%23openstack-qa/%23openstack-qa.2018-11-01.log.html#t2018-11-01T12:40:22
[5] http://lists.openstack.org/pipermail/openstack-dev/2018-September/134911.html