[kube-prometheus-stack] add serviceName option to prometheus CR

[trouaux]

What this PR does / why we need it

Adding serviceName option to Prometheus CR. This allows prometheus-operator reconciler to associate templated Service to Prometheus StatefulSet instead of creating an operated service.

see https://prometheus-operator.dev/docs/api-reference/api/#monitoring.coreos.com/v1.PrometheusSpec

Which issue this PR fixes

• fixes [kube-prometheus-stack] Missing spec prometheus.spec.serviceName #5272

Special notes for your reviewer

Checklist

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

[jkroepke]

In general, I like this change. Currently, the service is just prometheus-operated or alertmanager-operated and the are different from all other names.

However, this is a breaking changes. A lot of people may depend against the operated service names (including the helm chart itself + private deployments)

In order to approve this PR, my requirements are:

• fix all references to the hardcoded service names within the helm chart, e.g.

  helm-charts/charts/kube-prometheus-stack/templates/grafana/configmaps-datasources.yaml

  Line 54 in f4f38ef

  url: http://prometheus-{{ template "kube-prometheus-stack.prometheus.crname" $ }}-{{ . }}.prometheus-operated:9090/{{ trimPrefix "/" $.Values.prometheus.prometheusSpec.routePrefix }}

• Ensure, that the service generated by helm differs from the service name generated by the operator (https://github.com/prometheus-community/helm-charts/blob/f4f38ef92e6cb01433ac0e2546bed0774e3b9d7a/charts/kube-prometheus-stack/templates/prometheus/service.yaml)

• Add a toggle to disable the service generated by helm

• Bump the major version

• Add a note into the README and add a snippet how to restore the orginal behavior

And what about Alertmanager?

[trouaux]

• fix all references to the hardcoded service names within the helm chart, e.g.

  helm-charts/charts/kube-prometheus-stack/templates/grafana/configmaps-datasources.yaml

  Line 54 in f4f38ef

  url: http://prometheus-{{ template "kube-prometheus-stack.prometheus.crname" $ }}-{{ . }}.prometheus-operated:9090/{{ trimPrefix "/" $.Values.prometheus.prometheusSpec.routePrefix }}

• Ensure, that the service generated by helm differs from the service name generated by the operator (https://github.com/prometheus-community/helm-charts/blob/f4f38ef92e6cb01433ac0e2546bed0774e3b9d7a/charts/kube-prometheus-stack/templates/prometheus/service.yaml)
• Add a toggle to disable the service generated by helm
• Bump the major version
• Add a note into the README and add a snippet how to restore the orginal behavior

agree! I will work on those changes, thanks for the feedback

And what about Alertmanager?

Currently alertmanager spec does not support serviceName option, but there is open issue for it and ThanosRuler.
thanos-ruler-operated would be a third service

[jkroepke]

but there is open issue for it and ThanosRuler

good catch, but it seems implemented.

prometheus-operator/prometheus-operator#5632

---

I will contribute that feature to AM resource. Once implemented, they in this PR, all three components can be adjusted.

[trouaux]

but there is open issue for it and ThanosRuler

good catch, but it seems implemented.

prometheus-operator/prometheus-operator#5632

this should be just passing the name of the operated service which is created by default right now governingServiceName

definitely a place to think about when actually implementing the serviceName option

[jkroepke]

Maybe keep this on hold until upstream changes are done.

I would like to avoid 2 breaking changes.

[jkroepke]

Implementing PR Prometheus:

• Feat: Add servicename field to the Prometheus server and agent CRDs prometheus-operator/prometheus-operator#6687

Thanos

• monitoring.coreos.com/v1.ThanosRulerSpec to support labels on Service resource prometheus-operator/prometheus-operator#7317
• feat: add serviceName option to ThanosRuler and AlertManager CRD prometheus-operator/prometheus-operator#7325

Alertmanager

• Feat: Add serviceName field to the Alertmanager CRD prometheus-operator/prometheus-operator#7329