Add Prometheus annotations when smallrye metrics in enabled

[geoand]

Fixes: #10301

[geoand]

@maxandersen I wasn't able to find any information for the Prometheus specific application annotations on Openshift. Who is the best person to ask for this?

[gsmet]

This looks like a new feature, I'm not sure it's a good backport candidate.

[geoand]

OK, no problem.

[iocanel]

LGTM, I am wondering if in the future we also need to support the ServiceMonitor custom resource which is an operator based alternative to those annotations!

[geoand]

@brancz Hey! @maxandersen mentioned that you are the right person to help us figure out what the proper way of monitoring applications (via Prometheus) that are running on Openshift is.

To give you some context, in Quarkus we generate the Kubernetes / Openshift manifests based on the various capabilities the application has and we are wondering what Kubernetes manifests we should be generating in order to properly monitor a user application on Openshift.

Thanks!

[brancz]

Yes as @iocanel mentioned ServiceMonitors are the mechanism to use in OpenShift (and the larger Kubernetes ecosystem for anyone using the prometheus-operator, which is a very popular project and many people use it). In OpenShift everything will work out of the box with the new "user workload monitoring" feature when you create a ServiceMonitor.

[geoand]

Thanks @brancz, I'll check it out

[maxandersen]

thanks @brancz - just want to grok when the prometheus annotations are relevant and when they aren't - are you saying ServiceMonitor are the key and then prometheus annotations are irrelevant or should both be applied ?

[geoand]

Looks like we should start supporting the Prometheus CRD. @iocanel does dekorate have the ability to generate that?