portNumber field in Prometheus Operator PodMonitor CRD is ignored

[benediktwerner]

What's wrong?

The Prometheus Operator PodMonitor CRD (or rather the PodMetricsEndpoint CRD therein) has a portNumber field to allow setting the port number of the metrics endpoint to scrape: https://prometheus-operator.dev/docs/api-reference/api/#monitoring.coreos.com/v1.PodMetricsEndpoint

Alloy seems to ignore this configuration and only recognizes port (which can only reference named ports) and the deprecated targetPort (which can be used instead of portNumber but is deprecated):

alloy/internal/component/prometheus/operator/configgen/config_gen_podmonitor.go

Line 172 in b09bc31

if ep.Port != nil && *ep.Port != "" {

Probably because portNumber is somewhat new.

Steps to reproduce

Have a pod with two ports, e.g. 8080 and 9091, where 9091 should be used for metrics.

Create a PodMonitor resource something like this:

apiVersion: monitoring.coreos.com/v1
kind: PodMonitor
metadata:
  name: my-metrics
  namespace: default
spec:
  podMetricsEndpoints:
  - path: /metrics
    portNumber: 9091

Observe that Alloy tries to scrape metrics via port 8080.

System information

No response

Software version

Grafana Alloy 1.7.4

Configuration

Logs