Support InPlace upgrade for worker machines

[eromanova]

Currently, according to k0smotron docs, the InPlace upgrade (using autopilot) is supported for control plane machines only: https://docs.k0smotron.io/stable/update/update-capi-cluster/. It'll be good to support the same approach for worker machines as well if possible.

[github-actions]

The issue is marked as stale since no activity has been recorded in 30 days

[DinaBelova]

Dear k0smotron team, can you please share the plan on getting this fixed? This issue was opened some time ago and in general it's important for the k0rdent project experience. (cc @mestadler @p5ntangle fyi folks)

[jnummelin]

can you please share the plan on getting this fixed?

First of all, fix is the wrong word as this is a new feature, not a bug.

I'm not entirely sure if k0smotron can even "fix" this. The worker MachineDeployment object is fully controlled by CAPI core controllers and thus very hard to hook into via k0smotron.

From CAPI/k0rdent point of view, how would you want this to work? I.e. what are the expected steps to trigger worker InPlace update?

[eromanova]

From CAPI/k0rdent point of view, how would you want this to work?

From the k0rdent perspective, it would be great to have the same approach we currently use for the InPlace upgrade of ControlPlanes. The upgrade strategy (InPlace or Replace) could be configured within one of k0smotron’s public API objects, such as K0sWorkerConfigTemplate.

With the InPlace upgrade strategy, the node would not be recreated and all updated k0s settings (ex. k0s version) would be applied to the existing node.

I understand that implementing this in k0smotron may be difficult or even impossible, but I wanted to bring it up for discussion (just in case).

[jnummelin]

The main challenge is that K0sWorkerConfigTemplate , as all other CAPI XYZTemplate types, are not something that are really reconciled by any controller. They are merely "placeholders" when the actual types are created.

We can keep this still around if we come up with any idea how this could be done, but currently it seems pretty impossible to implement.

I wanted to bring it up for discussion (just in case)
Always good to have discussions around these kinda ideas. 😄