fix: update node annotation used to limit log spam with valid key

[brydoncheyney]

What type of PR is this?

/kind bug

What this PR does / why we need it:

#6265 introduced the ability for users to apply an annotation to cluster Nodes that are not managed by the autoscaler, reducing the amount of "spam" messages logged by the controller.

However, the chosen annotation key k8s.io/cluster-autoscaler/enabled is not a valid identifier - https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set - which expects only a single DNS prefix.

Attempting to manually add this annotation to an existing node will fail -

# nodes "ip-XXX-XXX-XXX-XXX.ec2.internal" was not valid:
# * metadata.annotations: Invalid value: "k8s.io/cluster-autoscaler/enabled": a qualified name must consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyName',  or 'my.name',  or '123-abc', regex used for validation is '([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]') with an optional DNS subdomain prefix and '/' (e.g. 'example.com/MyName')

Note that the use of the k8s.io/cluster-autoscaler/enabled tag is valid within AWS.

This PR uses a valid identifier k8s.io/cluster-autoscaler-enabled

Which issue(s) this PR fixes: 6300

Fixes #6300

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: brydoncheyney / name: Brydon Cheyney (7de0d94)

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[drmorr0]

OH, grumble.

I was thinking the tags got translated into annotations on the node but clearly not.

@gjtempleton can I can a second opinion on this? I feel less confident in my decision-making abilities now, lol

[vadasambar]

DNS regex validation check in kubernetes allows only a single /: https://github.com/kubernetes/kubernetes/blob/ec5096fa869b801d6eb1bf019819287ca61edc4d/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L45-L61

Seems like an easy to trip on thing.

[brydoncheyney]

DNS regex validation check in kubernetes allows only a single /: kubernetes/kubernetes@ec5096f/staging/src/k8s.io/apimachinery/pkg/util/validation/validation.go#L45-L61

Seems like an easy to trip on thing.

The annotation key/value format is well documented - https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/#syntax-and-character-set - but I think the confusion here is easy to understand when you consider the AWS tags used by the cluster autoscaler, which do not follow the same conventions and can contain arbitrary characters not support by k8s annotations/labels.

tldr: easy mistake to make

[vadasambar]

I will take a look if you don't mind @drmorr0 (we can get Guy to do the final review).

/assign @vadasambar

[vadasambar]

LGTM overall. Thank you for the PR. I will do one more pass tomorrow.

[vadasambar]

/lgtm

[vadasambar]

@gjtempleton need your approval 🙏

[gjtempleton]

Thanks for picking this up, agreed, on first pass my AWS tags brain couldn't see the problem.

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brydoncheyney, gjtempleton, vadasambar

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• cluster-autoscaler/cloudprovider/aws/OWNERS [gjtempleton]

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