[pve-devel] [PATCH ha-manager 09/15] manager: apply colocation rules when selecting service nodes

[Fiona Ebner]

Am 29.04.25 um 11:07 schrieb Daniel Kral:
> On 4/28/25 14:46, Fiona Ebner wrote:
>> I feel like we should trigger auto-migration for strict colocation
>> rules. I.e. apply the rules earlier in select_service_node(), before the
>> "keep current node" early return.
>>
>> With nofailback=0, we do not keep the current node when node priorities
>> change for HA groups or the service's group changes, so it feels
>> consistent to do the same for colocation rules. We'll need to be careful
>> not to get a "both services now migrate towards each other" switch-up
>> scenario of course.
> 
> What scenario would that be? Or do you mean just disallowing migrating
> services contradicting the HA (colocation) rules?

I just meant we need to be careful when implementing if we want to apply
new rules directly/honor them while services are running. E.g. say a new
rule vm:101<->vm:102 is introduced, with 101 on node A and 102 on node
B. Then the HA manager should only issue a migration command 101 to B or
102 to A, but not both of course.

>> We also don't hinder migrating against group priorities, where, with
>> nofailback=0, it will migrate straight back again. This can be improved
>> of course, but nothing new, so I'd consider it orthogonal to the
>> colocation implementation here.
> 
> Yes, it would improve UX to add migration blockers for these in the
> future as the info could be exposed there without putting too much
> dependency between pve-manager and pve-ha-manager.
> 
> I'll try to add the blockers for colocation rules for v1 or a follow-up.

Might be better as a follow-up/separate series, to not blow up the
series here too much.