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> Grenade uses devstack so once we have devstack on master installing
> (and configuring) placement from the new repo and disable installing
> and configuring it from the nova repo, that's the majority of the
> change I'd think.
>
> Grenade will likely need a from-rocky script to move any config that
> is necessary, but as you already noted below, if the new repo can live
> with an existing nova.conf, then we might not need to do anything in
> grenade since placement from the new repo (in stein) could then run
> with nova.conf created for placement from the nova repo (in rocky).

The from-rocky will also need to extract data from the nova-api database
for the placement tables and put it into the new placement database (as
real operators will have to do). It'll need to do this after the split
code has been installed and the schema has been sync'd. Without this,
the pre-upgrade resources won't have allocations known by the split
placement service. I do not think we should cheat by just pointing the
split placement at nova's database.

Also, ISTR you added some allocation/inventory checking to devstack via
hook, maybe after the tempest job ran? We might want to add some stuff
to grenade to verify the pre/post resource allocations before we start
this move so we can make sure they're still good after we roll. I'll see
if I can hack something up to that effect.

--Dan