[Feature Request] Prometheus widget should filter for active targets in API call

[davepgreene]

Description

Currently the prometheus widget calls {URL}/api/v1/targets which includes droppedTargets as well even though the actual widget component doesn't use them at all. This has the effect that response handling can be slow in a situation where there are a number of targets. For example, this is what the widget shows:

In my homepage container logs:

Listening on port 3000
[2025-02-03T16:27:05.098Z] warn: API response for /api/services/proxy?group=Monitoring%2FNetworking&service=Prometheus&index=0&endpoint=targets exceeds 4MB. API Routes are meant to respond quickly. https://nextjs.org/docs/messages/api-routes-response-size-limit

I did some quick calculations (from inside the homepage pod in k8s):

# curl -so /dev/null 'http://prometheus-internal.observability:9090/api/v1/targets' -w 'Unfiltered: %{size_download}\n
Unfiltered: 6589879
# curl -so /dev/null 'http://prometheus-internal.observability:9090/api/v1/targets?state=active' -w 'Filtered: %{size_download}\n'
Filtered: 197891

That's a reduction of 6391988 bytes. Granted my use case is probably a little extreme but if you note in the component code (https://github.com/gethomepage/homepage/blob/dev/src/widgets/prometheus/component.jsx#L27-L29) it's only using activeTargets anyway so grabbing all the data (which includes labels and discoveredLabels for each target, even if they're dropped) can really add up in terms of bytes over the wire.

I'm happy to contribute here, just let me know if you're interested.

Other

No response

[shamoon]

Sure thanks

See #4701

[davepgreene]

Incredible! Thanks so much 😄