Simple test with curl

Hi,

is it possible to do end to end testing purely with curl? (Similar to this setup https://github.com/prometheus-community/PushProx/blob/master/end-to-end-test.sh)

For testing I run node-exporter, proxy and client on the same machine:

pushprox-proxy --web.listen-address=":8080" --log.level=debug

pushprox-client --fqdn test.local --proxy-url "http://192.168.1.10:8080/"

prometheus node exporter running on 192.168.1.10:9100

I assume that if this is supposed to work I need to use proxy parameter in some way.
I tried to run it like this:

curl --proxy http://test.local:8080 http://test.local:9100/metrics

Not sure what am I doing wrong, but all I get is errors so far (strconv.ParseFloat: parsing "": invalid syntax).

Proxy log:

ts=2024-04-17T15:06:15.895Z caller=coordinator.go:115 level=info msg=DoScrape scrape_id=cefb3ed1-3d68-4f78-9ab8-084c469c56a8 url=http://test.local:9100/metrics
ts=2024-04-17T15:06:15.895Z caller=main.go:154 level=info msg="Responded to /poll" url=http://test.local:9100/metrics scrape_id=cefb3ed1-3d68-4f78-9ab8-084c469c56a8
ts=2024-04-17T15:06:15.897Z caller=coordinator.go:136 level=info msg=WaitForScrapeInstruction fqdn=test.local
ts=2024-04-17T15:06:15.898Z caller=main.go:135 level=info msg="Got /push" scrape_id=cefb3ed1-3d68-4f78-9ab8-084c469c56a8
ts=2024-04-17T15:06:15.898Z caller=coordinator.go:168 level=info msg=ScrapeResult scrape_id=cefb3ed1-3d68-4f78-9ab8-084c469c56a8

Client log:

ts=2024-04-17T15:07:43.770Z caller=main.go:206 level=info msg="Got scrape request" scrape_id=ab8c0768-2d88-47e0-a7a6-7fc7d5a43529 url=http://test.local:9100/metrics
ts=2024-04-17T15:07:43.770Z caller=main.go:96 level=error err="strconv.ParseFloat: parsing \"\": invalid syntax"
ts=2024-04-17T15:07:43.772Z caller=main.go:108 level=info msg="Pushed failed scrape response"

Is this something that should work? Or is Prometheus proxy request impossible to simulate with curl?

Use the linked end-to-end-test.sh as the starting reference and trace the proxy/client request flow represented by the logged /poll and /push entries. Reproduce the provided node-exporter, proxy, client, and curl commands, then compare the response and failure path. Done means a curl-only test has a clear, reproducible pass/fail result.