✨ kcp: add preflight check for pending version upgrade from topology

[chrischdi]

What this PR does / why we need it:

High-level description:

• KCP: block scale-up/scale-down/rollout/remediation if we know there is an upcoming version upgrade pending from the topology
• Topology: Do not block propagating changes anymore when the ControlPlane is in scaling state

Note: This change only affects topology based Clusters.

More detailed description:

Changes to KCP:

• Adds a preflight check for KCP for topology based clusters to check if there is an upgrade pending to get propagated down (Cluster.spec.topology.version != KCP.spec.version)
• From the perspective of KCP it should be better to roll-forward with the new desired spec instead of first continuing with the old (propably broken) spec of KCP

Changes to the topology controller:

• Relax computeControlPlaneVersion to allow to propagate down changes when a Control Plane is in scaling.
  • Note: this was only used for ControlPlane providers which implement replicas.
  • The ControlPlane provider itself should know better if it should first finish scaling or rollout the new desired state instead.
  • If this check would have been kept, the above preflight check could have lead to deadlocks when e.g.:
    • a CP machine was marked for remediation while the Cluster's .spec.topology.version was set to a newer one
    • triggering a scale-up or scale-down and immediately after update the Cluster's .spec.topology.version
    • pretty sure others too

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

/area provider/control-plane-kubeadm

[sbueringer]

Just some nits

[fabriziopandini]

Overall sgtm only one small suggestion on top of @sbueringer comments

[sbueringer]

Last nit

[fabriziopandini]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 2cc20dafe39490dd8ec3481a4ec49b13ec6f4f71

[sbueringer]

Thx!

/lgtm
/approve

/hold
Similar to the MS PR, will think about the big picture and then merge in a bit

/test pull-cluster-api-e2e-main

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 2d5643c166c8a6e8167c4b91e31a772dcc980356

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

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[sbueringer]

@chrischdi Did you intentionally revert the last commit?

[chrischdi]

/test pull-cluster-api-e2e-main

[sbueringer]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 2d5643c166c8a6e8167c4b91e31a772dcc980356

[k8s-ci-robot]

@chrischdi: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-apidiff-main	505b552	link	false	/test pull-cluster-api-apidiff-main

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[sbueringer]

Thanks!

/lgtm
/hold cancel

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 53b9c80552cb18a26e808fb1ca620ed3e11571b5