Add flag "--skip-addons" to kubeadm upgrade

[chenk008]

What would you like to be added?

Add flag "--skip-addons" to kubeadm upgrade, these addons upgrades will be skipped

Why is this needed?

In some certain scenarios, cluster administrators want to skip addons(i.e. coredns,kube-proxy) upgrades. The addons upgrades may affect the data plane, so administrators must be more careful to upgrade these addons.

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[neolit123]

/transfer kubeadm

[neolit123]

kubeadm upgrade checks if the addon config maps are missing and then does not perform upgrade of the addons. but the FR here is different, perhaps in such a case admins should skip the addons on init and deploy them with custom names, so that they are not managed by kubeadm upgrade too.

i think ideally this skip should be possible with upgrade phases. we have a plan to add them but it's a bit complicated.

#1318

i am generally -1 to add this new flag, but let's see what others think.

[neolit123]

Add flag "--skip-addons" to kubeadm upgrade

the flag should be for 'upgrade apply'

[chenk008]

@neolit123 kubeadm upgrade apply support --skip-phases option, it looks good to me.

[neolit123]

ok, let's keep this planned for:
#1318

[W1zzardTPU]

kubeadm upgrade checks if the addon config maps are missing and then does not perform upgrade of the addons

Great tip! I ran into the same issue with coredns (which we manage separately through ArgoCD). During upgrade kubeadm insisted that it really wanted to change some immutable values in the coredns deployment, so it kept failing.

My workaround was to change the coredns configmap name to something other than "coredns", so kubeadm couldn't find it and skipped that phase.