node-role.kubernetes.io/* docs are wrong

[sftim]

This is a Bug Report

Problem: Well-Known Labels, Annotations and Taints states that the only registered node role label is
node-role.kubernetes.io/control-plane.

Whilst that's true right now, we should have registered it as node-role.kubernetes.io/* where the * can be any node role.

Proposed Solution:
Update the docs:

• mention that nodes have an optional node role, where the allowed characters are limited by the syntax rules for labels
• update the list of well-known labels, annotations and taints

Pages to Update:

• https://kubernetes.io/docs/reference/labels-annotations-taints/
• https://kubernetes.io/docs/concepts/architecture/nodes/

See kubernetes/kubernetes#127507

/sig architecture
/sig node
/priority backlog

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[sftim]

Also relevant to aws/karpenter-provider-aws#1941 and the Karpenter-core equivalent issue (if there is one).

[sftim]

Just to make things a bit harder, there is also a taint node-role.kubernetes.io/control-plane. I don't know if that should also be node-role.kubernetes.io/*.

[utkarsh-singh1]

Just to make things a bit harder, there is also a taint node-role.kubernetes.io/control-plane. I don't know if that should also be node-role.kubernetes.io/*.

I think that taint is for pods to make them not to schedule on control-plane.

[Aaina26]

According to this comment kubernetes/kubernetes#127507 (comment), Node role node-role.kubernetes.io/master is no longer used by default by kubeadm. It is now replaced by node-role.kubernetes.io/control-plane. Maybe this section needs to be removed as well?

[sftim]

According to this comment kubernetes/kubernetes#127507 (comment), Node role node-role.kubernetes.io/master is no longer used by default by kubeadm. It is now replaced by node-role.kubernetes.io/control-plane. Maybe this section needs to be removed as well?

We need to redo the docs. We won't change them to not mention node-role.kubernetes.io/master at all; that would be unhelpful to readers.

[Aaina26]

Okay. Got it! Just to confirm:

1. We will add that the nodes have an optional node role to this page: https://kubernetes.io/docs/concepts/architecture/nodes/
2. And for this page: https://kubernetes.io/docs/reference/labels-annotations-taints/ ,I suggest that we only change the examples to reflect node-role.kubernetes.io/*. The title can help readers identify that the Taint is for control-plane or master.

If this sounds good, I would like to work on this. Any additional suggestions are most welcome.