[QG] Simulate Cluster upgrade sceanrio in KIM with SREs (upgrade of K8s version and VM image version)

[tobiscr]

Description

As pre-requisite for a Go-Live, we have to ensure that KIM is properly dealing with an upgrade of

• Kubernetes vesion
• VM image version

as we have to perform regularly updates on our SKR fleet.

AC:

• Get in touch with SRE to align how their upgrade process for Kubernetes version and VM image version looks like
• Simulate a upgrade-scenario by upgrading an Shoot-Cluster via KIM
• Prevent downgrades of machine image and kubernetes versions

Reasons

We have for beginning of Dec 2024 another SKR fleet upgrade scheduled and KIM has to be able to perform this upgrade properly

Attachments

[akgalwas]

Consider the following:

• When autoupdates are enabled we can be out of sync with Runtime CR (KEB is passing version)
• We need to implement a check that prevents from updating Kubernetes version when the version on Runtime CR is older. We should log some warning to the log, but still Runtime CR could be out of sync.

[akgalwas]

For now we need to prevent downgrades of kubernetes and image (we can use the version from the Runtime CR only if the version in the Runtime CR if greater than version on shoot)

[koala7659]

Related PR : #483

[tobiscr]

Covered by https://github.tools.sap/kyma/backlog/issues/6177

@vvxxvvxx - can you please confirm that you verified the successful upgrade of a K8s-version or VM-image-version of an Gardener cluster via KIM ?

We just need to know if KIM is able to upgrade an existing Gardener-Cluster correctly.

[vvxxvvxx]

Hi @tobiscr , performed a k8s version upgrade for a dev runtime. Please find the test result here. thanks.

[tobiscr]

Tested today the upgrade of image-version successfully. Findings are:

• No information logged if VM image or K8s version-downgrade was detected #537
• Log message of state includes the FROM-state but TO-state is sometimes empty #536