CAPVCD failure zones / node placement

[gawertm]

We might have to look into this at some point.

Context: https://gigantic.slack.com/archives/CE92C4BST/p1727765125494859

[gawertm]

placement policy exists in VCD machine template.
also the maintainers starting to work on zones, but not sure where they left off when leaving the project.
We should evaluate if we can use some feature like that or how much effort it would be to finish this feature

[anvddriesch]

placementPolicy: We can define this for vcd machine templates. It refers to a vm placement policy that needs to exist in the organisation already.
It appears that these placement policies work by being linked to vm groups that have specific affinites defined and therefore will place the vms according to these affinities.

failureDomain we can define this for vcd machine templates as well. However, the value needs to match to an entry in the map failureDomains in the vcd cluster status which in turn comes from the zones field in the multiZoneSpec of the vcd cluster.
it looks as though multiZoneSpec is implemented since it's present in the CRD and throughout the code as well. However, there are still some TODOs referring to the topology part like this one
making it look like it's not finished. I could not see any open issues (or closed issues for that matter actually) given more insight on the status.
I think we can just test these fields ourselves.

[gawertm]

xavier's comments https://gigantic.slack.com/archives/CE92C4BST/p1727770415141169?thread_ts=1727765125.494859&cid=CE92C4BST

[anvddriesch]

placementPolicy is supported in the chart and can be used.
Xavier will ask neoedge to create a placement policy for us that we can reference for testing.

[vxav]

Loris got back to me and said they can't really do it because it would mess a bit with the sheduling of the workloads since the environment is shared.

I'll ask the customer tomorrow during the sync if they can create the DRS groups, rules and placement policy to test it with Glasgow or Tamarin.

[vxav]

I created an issue in the customer board with details on how this works
https://github.com/giantswarm/telekom-panamax/issues/337

[vxav]

The feature is there. We can close in favor of ☝