Prometheus target dropped when using k8c.spec.cassandra.datacenters.datacenterName

[Arun-Trichy]

What happened?
When we override the k8c.spec.cassandra.datacenters.datacenterName also enabling telemetry for monitoring, Prometheus is dropping the target due to selector label mismatch.

Did you expect to see something different?
Prometheus should be able to monitor the cassandra instance even with datacenterName override.

How to reproduce it (as minimally and precisely as possible):
Enable telemetry & override the datacenterName

Environment

• K8ssandra Operator version: v1.15.0
• Kubernetes version information:
  Client Version: v1.28.3
  Kustomize Version: v5.0.4-0.20230601165947-6ce0bf390ce3
  Server Version: v1.29.1
• Kubernetes cluster kind:
  kind cluster v1.29.1
• Manifests:

apiVersion: k8ssandra.io/v1alpha1
kind: K8ssandraCluster
metadata:
  name: axone-dsecluster
spec:
  cassandra:
    config:
      cassandraYaml:
        ...
      dseYaml:
        ...
      jvmOptions:
        ...
    datacenters:
    - datacenterName: Cassandra
      metadata:
        name: dc1
      racks:
      - name: rack1
      resources:
        limits:
          memory: 40Gi
        requests:
          cpu: 3
          memory: 17.5Gi
      size: 1
      storageConfig:
        cassandraDataVolumeClaimSpec:
          accessModes:
          - ReadWriteOnce
          resources:
            requests:
              storage: 300Gi
    serverType: dse
    serverVersion: 6.8.47
    telemetry:
      cassandra:
        endpoint:
          address: 0.0.0.0
          port: "9000"
      mcac:
        enabled: false
      prometheus:
        enabled: true

Anything else we need to know?:
Selector used in SVC vs ServiceMonitor


Prometheus Target Empty

┆Issue is synchronized with this Jira Story by Unito
┆Issue Number: K8OP-252