Sounds like an important discussion to have with the operators in Denver. Should put this on the schedule for the Ops meetup.
--Rocky > -----Original Message----- > From: Matt Riedemann [mailto:mriede...@gmail.com] > Sent: Thursday, September 06, 2018 1:59 PM > To: OpenStack Development Mailing List (not for usage questions) > <openstack-...@lists.openstack.org>; openstack- > operat...@lists.openstack.org > Subject: [openstack-dev] [nova][placement][upgrade][qa] Some upgrade- > specific news on extraction > > I wanted to recap some upgrade-specific stuff from today outside of the > other [1] technical extraction thread. > > Chris has a change up for review [2] which prompted the discussion. > > That change makes placement only work with placement.conf, not > nova.conf, but does get a passing tempest run in the devstack patch [3]. > > The main issue here is upgrades. If you think of this like deprecating config > options, the old config options continue to work for a release and then are > dropped after a full release (or 3 months across boundaries for CDers) [4]. > Given that, Chris's patch would break the standard deprecation policy. Clearly > one simple way outside of code to make that work is just copy and rename > nova.conf to placement.conf and voila. But that depends on *all* > deployment/config tooling to get that right out of the gate. > > The other obvious thing is the database. The placement repo code as-is > today still has the check for whether or not it should use the placement > database but falls back to using the nova_api database [5]. So technically you > could point the extracted placement at the same nova_api database and it > should work. However, at some point deployers will clearly need to copy the > placement-related tables out of the nova_api DB to a new placement DB and > make sure the 'migrate_version' table is dropped so that placement DB > schema versions can reset to 1. > > With respect to grenade and making this work in our own upgrade CI testing, > we have I think two options (which might not be mutually > exclusive): > > 1. Make placement support using nova.conf if placement.conf isn't found for > Stein with lots of big warnings that it's going away in T. Then Rocky > nova.conf > with the nova_api database configuration just continues to work for > placement in Stein. I don't think we then have any grenade changes to make, > at least in Stein for upgrading *from* Rocky. Assuming fresh devstack installs > in Stein use placement.conf and a placement-specific database, then > upgrades from Stein to T should also be OK with respect to grenade, but > likely punts the cut-over issue for all other deployment projects (because we > don't CI with grenade doing > Rocky->Stein->T, or FFU in other words). > > 2. If placement doesn't support nova.conf in Stein, then grenade will require > an (exceptional) [6] from-rocky upgrade script which will (a) write out > placement.conf fresh and (b) run a DB migration script, likely housed in the > placement repo, to create the placement database and copy the placement- > specific tables out of the nova_api database. Any script like this is likely > needed regardless of what we do in grenade because deployers will need to > eventually do this once placement would drop support for using nova.conf (if > we went with option 1). > > That's my attempt at a summary. It's going to be very important that > operators and deployment project contributors weigh in here if they have > strong preferences either way, and note that we can likely do both options > above - grenade could do the fresh cutover from rocky to stein but we allow > running with nova.conf and nova_api DB in placement in stein with plans to > drop that support in T. > > [1] > http://lists.openstack.org/pipermail/openstack-dev/2018- > September/subject.html#134184 > [2] https://review.openstack.org/#/c/600157/ > [3] https://review.openstack.org/#/c/600162/ > [4] > https://governance.openstack.org/tc/reference/tags/assert_follows- > standard-deprecation.html#requirements > [5] > https://github.com/openstack/placement/blob/fb7c1909/placement/db_api > .py#L27 > [6] https://docs.openstack.org/grenade/latest/readme.html#theory-of- > upgrade > > -- > > Thanks, > > Matt > > __________________________________________________________ > ________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: OpenStack-dev- > requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev _______________________________________________ OpenStack-operators mailing list OpenStack-operators@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
