Expose prometheusexporter port in collector pod

[pavolloffay]

Use case: I want to use https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter/prometheusexporter to export pipeline's metrics to prometheus by using the podmonitor.
The podmonitor has config to set the port as string https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/api.md#endpoint.

When prometheusexporter is enabled the port is not exposed as container port on the collector

    exporters:
      prometheus:
        endpoint: 0.0.0.0:8889

    name: otc-container
    ports:
    - containerPort: 8888
      name: metrics
      protocol: TCP
    - containerPort: 4317
      name: otlp-grpc
      protocol: TCP
    - containerPort: 4318
      name: otlp-http
      protocol: TCP
    - containerPort: 55681
      name: otlp-http-legac
      protocol: TCP

[pavolloffay]

Basically the prometheus exporter cannot be used with the operator because the exporter port is not exposed in the collector container and the pod monitor requires it.

The workaround is to expose port directly in the CR

apiVersion: monitoring.coreos.com/v1
kind: PodMonitor
metadata:
  name: otel-collector
spec:
  namespaceSelector:
    matchNames:
    - observability
  selector:
    matchLabels:
      app.kubernetes.io/name: otel-collector
  podMetricsEndpoints:
  - port: metrics
  - port: promexporter


  mode: deployment
  ports:
    - name: promexporter
      port: 8889
      protocol: TCP

[yuriolisa]

Can I work on this one?

[iblancasa]

@yuriolisa go ahead :)