Allow passing feature flags to Prometheus receiver

[dnutels]

Is your feature request related to a problem? Please describe.

Ability to enable exemplars, currently an experimental feature, for the Prometheus receiver. For "vanilla" Prometheus
it is done via --enable-feature=exemplar-storage.

Describe the solution you'd like

Looking for a way to pass Prometheus flags to the ADOT collector.

Reason — exemplars are behind a feature flag, that for “regular” Prometheus would be passed (using docker compose as an example) like this:

services:
  ...
  prometheus:
    image: prom/prometheus:latest
    command: 
      - '--config.file=/etc/prometheus/prometheus.yml'
      - '--enable-feature=exemplar-storage'
    volumes:
      - ${PWD}/infra/prometheus/config.yml:/etc/prometheus/prometheus.yml
    ports:
      - '9090:9090'

Then prometheus would scrape OpenMetrics format with exemplars… equivalent to:

curl example.com:3000/metrics -H "Accept: application/openmetrics-text"

Describe alternatives you've considered

OTEL collector or N/A

Additional context

N/A

[Aneurysm9]

Support for exemplars in the upstream prometheus receiver is tracked with this issue. It should not be necessary to support the exemplar-storage feature flag as that controls whether exemplars are stored in the TSDB, which is not is use by the collector.

[dnutels]

Correct me here, but without this flag, these are currently not collected or shipped from the receiver forward.

My thinking was -- since, at this point, the receiver is a minimal implementation, perhaps enabling experimental flag in the upstream/adot would be a quicker/simpler stop-gap solution, which Prometheus already provides.

[github-actions]

This issue is stale because it has been open 60 days with no activity. Remove stale label or comment or this will be closed in 30 days.

[github-actions]

This issue was closed because it has been marked as stale for 30 days with no activity.

[ckt114]

Are there any plan to allow --enable-feature to be passed into prometheus receiver?