features: add ContextualLogging

[pohly]

This is a new feature in 1.24. Only the infrastructure is going in at this
point with no changes in Kubernetes components, so the user-visible effect is
minimal.

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[pohly]

/hold

Code PRs needs to be merged first.

[sftim]

Is there any documentation on https://k8s.dev/ about contextual logging? Ideally, we'd make sure that there was.

[pohly]

Not yet, because it currently doesn't make a difference for end-users.

[pohly]

See content/en/docs/concepts/cluster-administration/system-logs.md for an explanation based on the example command.

[pohly]

Oh, wrong site. For developers I have kubernetes/community#6560 pending. Should that document be moved to k8s.dev?

[sftim]

@pohly maybe what we should try to document is the format of logs when you select --logging-format=json as a cluster operator.

This feature gate is something we could mention on the page that describes that format, I think?

[sftim]

/sig instrumentation

[mehabhalodiya]

/assign @chrisnegus

[pohly]

maybe what we should try to document is the format of logs when you select --logging-format=json as a cluster operator.

This feature gate is something we could mention on the page that describes that format, I think?

The feature is independent of the output format.

[sftim]

Imagine a new reference page titled “Logging Output” or “Logging Formats”. Could we mention in that page the effect that this feature gate has on what output you get?

[pohly]

Imagine a new reference page titled “Logging Output” or “Logging Formats”. Could we mention in that page the effect that this feature gate has on what output you get?

Right now: none 😅 I could make something up, but that doesn't seem useful.

First some Kubernetes components must use the new infrastructure to extend their log output. kube-scheduler is likely to be the first candidate, but given that the infrastructure is going in late in the 1.24 cycle, those changes are probably not going to make the cut.

[pohly]

I remembered that I had extended the logging example so that it does contextual logging and has the --feature-gates parameter. I can use that as example in an overview section for the feature.

[pohly]

/hold cancel

Code PRs were merged, this can get included in the 1.24 documentation now. I've also extended system-logs.md with information about the feature.

[mehabhalodiya]

enhancement ref: kubernetes/enhancements#3077

[chrisnegus]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: d241ecaf57cefcc9e6b6786b3ead4a25c002d72d

[tengqm]

/approve
Kicking this in since the mechanism is in place anyway.
Would like to see how structured/contextual logging behaves in each component.

[k8s-ci-robot]

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