Upgrading kubeadm clusters - version notes out of date

[kfox1111]

Now that this has merged:
kubernetes/kubernetes#120825

The documentation needs to be upgraded to let folks know node versions can be behind more then 1.

[thisisharrsh]

/language en
/sig docs

[thisisharrsh]

Page related to the issue: https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/

[neolit123]

Now that this has merged: kubernetes/kubernetes#120825

The documentation needs to be upgraded to let folks know node versions can be behind more then 1.

it's kubelet versions to be precise, but kubeadm has no way to catch and verify what version of the kubelet the user deployed today. as can be seen in the doc here:
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/
kubelet upgrade happens out-of-band (after kubeadm upgrade has finished).

that's a bit of a design problem...

there were some AIs and some discussion here:
kubernetes/kubeadm#2924
kubernetes/kubeadm#2626

we currently have e2e tests that verify the kubeadm vs kubelet skew, but there are some gotchas around kubelet flags.
i'd claim the whole kubernetes/kubernetes#120825 change as supported, but i'm tentative around calcimining announcing it more widely in the docs.

perhaps we can say something like this in a small note near the top:

• it's recommended to match your kubelet and kubeadm versions, but you can also use an older kubelet version
• and link to https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#kubeadm-s-skew-against-the-kubelet

[neolit123]

/sig cluster-lifecycle
PRs welcome.

[neolit123]

/triage accepted

[pegasas]

/assign @pegasas
I will raise an PR for fixing this.

[pegasas]

PR merge.
Request to close this issue.
/close

[k8s-ci-robot]

@pegasas: Closing this issue.

In response to this:

PR merge.
Request to close this issue.
/close

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