Make KubeadmConfig and the KubeadmConfigTemplate immutable

[fabriziopandini]

KubeadmConfigTemplate are currently mutable but nor MachinePool nor MachineDeployments trigger rollout in case of changes assuming templates immutable. I suggest we make it immutable like all the other templates

Alsi KubeadmConfig is currently mutable, which does not make much sense given that it will processed only once right at the beginning of the machine lifecycle. Let's make this immutable as well.

Note: this is a breaking change, most probably it should wait for the next API version (unless we consider it a bug). opinions?

/kind api-change

[sbueringer]

We had a short discussion about this in Slack: https://kubernetes.slack.com/archives/C8TSNPY4T/p1627022324424100

Based on the discussion I would assume we could go ahead and consider this fixing a UX bug.

/cc @enxebre @CecileRobertMichon @vincepri @fabriziopandini (to be sure)

P.S. We could also mention this in the CAPI meeting tomorrow?

[fabriziopandini]

+1 for me, let put this in agenda for tomorrow

[randomvariable]

Can't remember if it was something the New Relic folk we're doing, though I thought that was mostly KCP no kubeadmconfigtemplates. cc @dthorsen

Not sure how relevant it is for them given they're using EKS and AWSManagedMachinePool now.

[vincepri]

/milestone Next

[sbueringer]

As discussed in the meeting today, we're considering this a breaking (behavioral) change.

We also identified a gap in the documentation on how to properly "update" KubeadmConfigTemplates (I'll open a PR for it)

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/lifecycle stale

[fabriziopandini]

/lifecycle frozen

[randomvariable]

/area control-plane

[sbueringer]

If we ever want to do this for KubeadmConfigTemplate, we have to make sure it does't break SSA dry-run (just like we did for DockerMachineTemplate)

[chrischdi]

I think this should be good to implement after #6710 got merged :-)

/assign

[sbueringer]

Please note:

As discussed in the meeting today, we're considering this a breaking (behavioral) change.

[chrischdi]

/unassign

Due to:

Note: this is a breaking change, most probably it should wait for the next API version (unless we consider it a bug). opinions?

[fabriziopandini]

/triage accepted

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/remove-triage accepted

[fabriziopandini]

/priority important-longterm

[fabriziopandini]

Note.
There are slightly related discussion about how to use KubeadmConfig for MachinePoois, but otherwise still worth to do it as soon as we bump a new API version
/help
/triage accepted

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In response to this:

Note.
There are slightly related discussion about how to use KubeadmConfig for MachinePoois, but otherwise still worth to do it as soon as we bump a new API version
/help
/triage accepted

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