feat(examples,metrics,kube-state-metrics): add configmap and promethe…

[sebastiangaiser]

…us-rules

In order to implement https://github.com/strimzi/proposals/blob/main/087-monitoring-of-custom-resources.md an initial version of the configmap and prometheus-rules are added for 'KafkaUser' and 'KafkaTopic' resources.

Part of #10276

Type of change

• Enhancement / new feature

Description

See commit message

Checklist

Please go through this checklist and make sure all applicable tasks have been done

• Write tests
• Make sure all tests pass
• Update documentation
• Check RBAC rights for Kubernetes / OpenShift roles
• Try your changes from Pod inside your Kubernetes and OpenShift cluster, not just locally
• Reference relevant issue(s) and close them after merging
• Update CHANGELOG.md
• Supply screenshots for visual changes, such as Grafana dashboards

[sebastiangaiser]

I'm unsure wehter KafkaTopic could also have a DeprecatedFields status field or not.
In addition a Deployment and PodMonitor should be added.

[scholzj]

I'm unsure wheter KafkaTopic could also have a DeprecatedFields status field or not.

At least in theory, all resources might have those. But I think for example KafkaTopic does not have anything deprecated right now. But I would have it covered for all resources and in the worst case, the alert will never be raised. If you don't add it now, we will likely forget to add it if we one day deprecate something there.

[sebastiangaiser]

But I would have it covered for all resources

@scholzj I added the deprecated field assuming it follows the same structure in the status object.

[scholzj]

I think this looks good. But it would be great to probably:

• Have some README.md file here explaining what this is and how to use it?
• Maybe we can add some simple chapter to the end of this section in the docs (https://strimzi.io/docs/operators/latest/full/deploying.html#assembly-metrics-str) that would at least mention this as well?

[ppatierno]

I had a first pass and agree with Jakub on what's missing. I will have another pass when the upgrades are committed.

[sebastiangaiser]

I've tried to address your points:

• added a README in the example directory
• added a section to the documentation. Tbh I've never worked with AsciiDoc before, so please guide me a bit here ;)

In addition I added a KSM deployment (similar as it already exists for Grafana) for clarifying how a Kubernetes deployment could look like. I've decided against the PodMonitor and for the Service + ServiceMonitor for simpler docs. Hope this is fine for you, too.

[scholzj]

LGTM. Thanks.