GA Metrics Cardinality Enforcement

[rexagod]

• One-line PR description: Mark the feature as stable, since we've been on beta for a while now.

• Issue link: Metric cardinality enforcement #2305

[dgrisonnet]

/assign

[dgrisonnet]

/assign @dashpole

[sftim]

Do we still support disabling it?

[johnbelamaric]

I don't think we have historically flipped that after reaching GA. For the next year at least, people will be using older versions so it's still relevant for those. Not very consistent though. FYI, looks like 94 of "stable" KEPs still say "true", 25 say "false" (not sure if they were always false though):

[hi on] jbelamaric@jbelamaric:~/proj/gh/kubernetes/enhancements$ grep ^disable-supported $(grep -l '^stage: stable' $(find . -name kep.yaml)) | cut -d : -f 3 | sort | uniq -c
     25  false
     94  true
[hi on] jbelamaric@jbelamaric:~/proj/gh/kubernetes/enhancements$ 

[sftim]

Generally available means you can't disable the feature gate, according to https://kubernetes.io/docs/reference/command-line-tools-reference/feature-gates/#feature-stages

[johnbelamaric]

PRR looks good, we need SIG approval though.

Do we have any tooling/plan to identify potential run-away metrics cardinality so we can preemptively deal with this, rather than making the admin do it ad hoc?

[dgrisonnet]

/lgtm
/approve

[dgrisonnet]

@johnbelamaric we thought about that in the past not only in Kubernetes but also with the Prometheus community but we haven't been able to find any solution that would allow us to do it preemptively without too much overhead. Here is a thread I started at some point, but we didn't pursue it prometheus/client_golang#970.

Since this cardinality enforcement method has been in place and metrics are more actively reviewed and developers are generally more aware of cardinality issues, cardinality explosions have been extremely rare and so we haven't discuss adding a preemptive mechanism since.

[johnbelamaric]

/approve

[k8s-ci-robot]

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