[kube-prometheus-stack] Enable otlp receiver

[truongnht]

Is your feature request related to a problem ?

For new Prometheus 3.0 to receive OTLP metrics, OTLP receiver feature needs to be enabled via cli arg web.enable-otlp-receiver. This option is not available at this moment in helmchart.

Describe the solution you'd like.

Add option to enable otlp-receiver

Describe alternatives you've considered.

n/a

Additional context.

No response

[bartvanackooij]

You could use the additonalArgs on the prometheus.prometheusSpec to enable it:

prometheus:
  prometheusSpec:
    additionalArgs:
      - name: web.enable-otlp-receiver
        value: ""

[truongnht]

@bartvanackooij let me try out, thanks

[kitforbes]

Edit: I misunderstood how Prometheus was using OTLP. The OpenTelemetry Demo was a good reference for configuring this correctly.

What would be required to also open port 4317 and/or 4318 (the typical OTLP ports) on the Prometheus service/pod? I've tried the following with no luck so far.

prometheus:
  prometheusSpec:
    additionalArgs:
    - name: web.enable-otlp-receiver
      value: ""
    additionalConfig:
      otlp:
        promoteResourceAttributes:
        - service.instance.id
        - service.name
        - service.namespace
        - cloud.availability_zone
        - cloud.region
        - container.name
        - deployment.environment.name
        - k8s.cluster.name
        - k8s.container.name
        - k8s.cronjob.name
        - k8s.daemonset.name
        - k8s.deployment.name
        - k8s.job.name
        - k8s.namespace.name
        - k8s.pod.name
        - k8s.replicaset.name
        - k8s.statefulset.name
        translationStrategy: NoUTF8EscapingWithSuffixes
    tsdb:
      outOfOrderTimeWindow: 30m
  service:
    additionalPorts:
    - name: otlp
      port: 4317
      targetPort: 4317

[pieterv-icloud-com]

If followed the instructions here: https://prometheus.io/docs/guides/opentelemetry/#send-opentelemetry-metrics-to-the-prometheus-server

I then configured an opentelemetry otel exporter with a similar url: https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/otlphttpexporter/README.md

The otel exporter complained about an invalid port because it is not expecting the path in the url.