On Wed, Jun 24, 2015 at 11:44 AM, Joe Gordon <joe.gord...@gmail.com> wrote:
> > > On Wed, Jun 24, 2015 at 11:03 AM, Sean Dague <s...@dague.net> wrote: > >> On 06/24/2015 01:41 PM, Russell Bryant wrote: >> > On 06/24/2015 01:31 PM, Joe Gordon wrote: >> >> >> >> >> >> On Tue, Jun 16, 2015 at 9:58 AM, Sean Dague <s...@dague.net >> >> <mailto:s...@dague.net>> wrote: >> >> >> >> Back when Nova first wanted to test partial upgrade, we did a >> bunch of >> >> slightly odd conditionals inside of grenade and devstack to make >> it so >> >> that if you were very careful, you could just not stop some of the >> old >> >> services on a single node, upgrade everything else, and as long as >> the >> >> old services didn't stop, they'd be running cached code in memory, >> and >> >> it would look a bit like a 2 node worker not upgraded model. It >> worked, >> >> but it was weird. >> >> >> >> There has been some interest by the Nova team to expand what's not >> being >> >> touched, as well as the Neutron team to add partial upgrade testing >> >> support. Both are great initiatives, but I think going about it >> the old >> >> way is going to add a lot of complexity in weird places, and not >> be as >> >> good of a test as we really want. >> >> >> >> Nodepool now supports allocating multiple nodes. We have a >> multinode job >> >> in Nova regularly testing live migration using this. >> >> >> >> If we slice this problem differently, I think we get a better >> >> architecture, a much easier way to add new configs, and a much more >> >> realistic end test. >> >> >> >> Conceptually, use devstack-gate multinode support to set up 2 >> nodes, an >> >> all in one, and a worker. Let grenade upgrade the all in one, >> leave the >> >> worker alone. >> >> >> >> I think the only complexity here is the fact that grenade.sh >> implicitly >> >> drives stack.sh. Which means one of: >> >> >> >> 1) devstack-gate could build the worker first, then run grenade.sh >> >> >> >> 2) we make it so grenade.sh can execute in parts more easily, so >> it can >> >> hand something else running stack.sh for it.' >> >> >> >> 3) we make grenade understand the subnode for partial upgrade, so >> it >> >> will run the stack phase on the subnode itself (given credentials). >> >> >> >> This kind of approach means deciding which services you don't want >> to >> >> upgrade doesn't require devstack changes, it's just a change of the >> >> services on the worker. >> >> >> >> We need a volunteer for taking this on, but I think all the follow >> on >> >> partial upgrade support will be much much easier to do after we >> have >> >> this kind of mechanism in place. >> >> >> >> >> >> I think this is a great approach for the future of partial upgrade >> >> support in grenade. I would like to point out step 0 here, is to get >> >> tempest passing consistently in multinode. >> >> >> >> Currently the neutron job is failing consistently, and nova-network >> >> fails roughly 10% of the time due >> >> to https://bugs.launchpad.net/nova/+bug/1462305 >> >> and https://bugs.launchpad.net/nova/+bug/1445569 >> > >> > If multi-node isn't reliable more generally yet, do you think the >> > simpler implementation of partial-upgrade testing could proceed? I've >> > already done all of the patches to do it for Neutron. That way we could >> > quickly get something in place to help block regressions and work on the >> > longer-term multinode refactoring without as much time pressure. >> >> The thing is, these partial service bits are sneaker than one realizes >> over time. There have been all kinds of edge conditions that crept up on >> the n-cpu one that are really subtle because code is running in memory >> on stale versions of dependencies which are no longer on disk. And the >> number of people that have this model in their head is basically down to >> a SPOF. >> > > I agree, As the author of the current multinode job it is definitely a > ugly hack (but one that has worked surprisingly well until now). > > >> >> The fact that neutron-grenade is at a 40% fail rate right now (and has >> been for over a week) is not preventing anyone from just rechecking to >> get past it. So I think assuming additional failing grenade tests are >> going to keep folks from landing bugs is probably not a good assumption. >> Making the whole path more complicated for other people to debug is an >> explosion waiting to happen. >> >> So I do want to take a hard line on doing this right, because the debt >> here is higher than you might think. The partial code was always very >> conceptually fragile, and fails in really funny ways some times, because >> of the fact that old is not isolated from new in a way that would be >> expected. >> > > Assuming the smoke jobs work, I don't think making grenade do mulitnode > should take very long. In which case we get a much more realistic upgrade > situation. > > Good news, it looks like both smoke jobs are working (ignoring failures from https://review.openstack.org/#/c/195748/). > >> I -1ed the n-net partial upgrade changes for the same reason. >> >> -Sean >> >> -- >> Sean Dague >> http://dague.net >> >> __________________________________________________________________________ >> 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 >> > >
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