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

From: Daniel Kral <d.kral@proxmox.com>
To: "Fiona Ebner" <f.ebner@proxmox.com>,
	"Proxmox VE development discussion" <pve-devel@lists.proxmox.com>,
	"Fabian Grünbichler" <f.gruenbichler@proxmox.com>
Subject: Re: [pve-devel] [PATCH ha-manager 09/15] manager: apply colocation rules when selecting service nodes
Date: Tue, 29 Apr 2025 11:07:14 +0200	[thread overview]
Message-ID: <ce9a801d-c28b-4480-a402-488448836a1f@proxmox.com> (raw)
In-Reply-To: <5f66e849-66b7-4ba4-a8d4-e4172a4f5055@proxmox.com>

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?

> 
> 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.

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