[ClusterLabs] colocation constraint - do I get it all wrong?

[lejeczek]

On 01/01/2024 18:28, Ken Gaillot wrote:
> On Fri, 2023-12-22 at 17:02 +0100, lejeczek via Users wrote:
>> hi guys.
>>
>> I have a colocation constraint:
>>
>> -> $ pcs constraint ref DHCPD
>> Resource: DHCPD
>>    colocation-DHCPD-GATEWAY-NM-link-INFINITY
>>
>> and the trouble is... I thought DHCPD is to follow GATEWAY-NM-link,
>> always!
>> If that is true that I see very strange behavior, namely.
>> When there is an issue with DHCPD resource, cannot be started, then
>> GATEWAY-NM-link gets tossed around by the cluster.
>>
>> Is that normal & expected - is my understanding of _colocation_
>> completely wrong - or my cluster is indeed "broken"?
>> many thanks, L.
>>
> Pacemaker considers the preferences of colocated resources when
> assigning a resource to a node, to ensure that as many resources as
> possible can run. So if a colocated resource becomes unable to run on a
> node, the primary resource might move to allow the colocated resource
> to run.
So what is the way to "fix" this - is it simply low/er score 
for such constraint?
In my case _dhcpd_ is important but if fails sometimes as 
it's often tampered with, so... make _dhcpd_ flow 
gateway_link but just fail _dhcp_ (it it keeps failing) and 
leave _gateway_link_ alone if/where it's good.
Or perhaps there a global config/param for whole cluster 
behaviour?