[prometheus-kube-stack] Fix relabeling and metricRelabeling for additional serviceMonitor

[mehr74]

What this PR does / why we need it

The current kube-prometheus-stack does not allow relabeling and metricRelabeling for additional service monitors. The issue is that, these values are not placed under endpoint and we get the following error.

Error: INSTALLATION FAILED: unable to build kubernetes objects from release manifest: error validating "": error validating data: ValidationError(ServiceMonitor.spec): unknown field "relabelings" in com.coreos.monitoring.v1.ServiceMonitor.spec

The MR moves metricRelabeling and relabeling under endpoint. To test the helm chart one can use the following values.

prometheus:
  additionalServiceMonitors:
    - name: test                          
      selector:
        matchLabels:
          app.kubernetes.io/name: test 
      namespaceSelector:
        matchNames:
          - test
      endpoints:
        - path: /metrics
          port: http
      relabelings:
      - sourceLabels: [__meta_kubernetes_pod_node_name]
        separator: ;
        regex: ^(.*)$
        targetLabel: nodename
        replacement: $1
        action: replace

Which issue this PR fixes

• fixes #
  [prometheus-kube-stack] Unable to add metricRelabeling to additionalServiceMonitor #5120
  [prometheus-kube-stack] Fix relabeling and metricRelabeling for additional serviceMonitor #5125

Special notes for your reviewer

Checklist

• DCO signed
• Chart Version bumped
• Title of the PR starts with chart name (e.g. [prometheus-couchdb-exporter])

[mehr74]

Hi @jkroepke,

Thanks a lot for your feedback on the code here. I forgot to sign-off last commit in my last branch. Could you please review once again?

[jkroepke]

Sorry for another review here. But I take note here this result into a invalid YAML, if jobLabel is defined above.

Also it may leads into unexpected results, if endpoints contains multiple endpoint items.

Since the relabelings config can be part of the endpoints config as well. I think removing the 2 options would be the best possible option here.