consider add more verbosity to error for http span sender

[Dentrax]

Requirement - what kind of business use case are you trying to solve?

It's a bit hard to distinguish why collector return non-200 errors, like as following:

prometheus-prometheus-operator-kube-p-prometheus-0 thanos-sidecar {"caller":"logger.go:22","level":"error","msg":"error reporting span \"/thanos.Store/Info\": error from collector: 404","ts":"2021-09-10T18:02:45.713894993Z"}

We could not figure it out which endpoint it tries to send for, with what method and maybe body?

It had better to error out: with this request: [POST] http://foo/bar:8080 i got 404 instead of i got 404.

Problem - what in Jaeger blocks you from solving the requirement?

This line throws the error from collector: %d errors.

This function actually.

Proposal - what do you suggest to solve the problem or improve the existing situation?

• We can add a debug log here before sending the request: req.String() maybe?

• We can enrich the verbosity of this error:

  if resp.StatusCode >= http.StatusBadRequest {
  return fmt.Errorf("error from collector: request: %s, got status: %d", req.String(), resp.StatusCode)
  }

Wdyt?