Unable to start Prometheus when Knative enabled.

[weimeilin79]

Try enable prometheus for a knative service, but had error..

kamel run API.java --open-api openapi.yaml --trait prometheus.enabled=true

Cannot reconcile Integration api: error executing post actions: error during replace resource: could not create or replace resource api: admission webhook "validation.webhook.serving.knative.dev" denied the request: validation failed: Port name prometheus is not allowed: spec.template.spec.containers[0].ports
Name must be empty, or one of: 'h2c', 'http1'

[davsclaus]

@nicolaferraro I think this would be good to get done before GA

[nicolaferraro]

This is for sure a cool feature, but we need to investigate if it's currently technically possible without changes in Knative, because afaik Knative itself publishes a prometheus endpoint and exposes metrics for their internal prometheus and for the pod autoscaler.

[astefanutti]

It should be fixed with #1478. I've tested it with Knative auto-scaling:

It shows discontinuities when the integration scales to zero. The metrics are reset per pods, which I think is acceptable.