Query-frontend doesn't log request details when request is cancelled

[yvrhdn]

Describe the bug

The query-frontend logs some details about the query when it completes, for example:

level=info ts=2021-11-25T11:32:38.59660534Z caller=handler.go:96 tenant=1 method=GET traceID=57060d6b589d1903 url="/tempo/api/search?x-dbg-exhaustive=true&limit=20" duration=7.079269575s response_size=96 status=200

If you cancel the request before it completes, this log does not appear.

To Reproduce

Steps to reproduce the behavior:

1. Run Tempo (single binary or distributed, shouldn't matter)
2. Monitor logs from the query-frontend
3. Perform a query that is slow (so you have enough time to cancel it)
4. Cancel the request
5. Nothing is logged by the query-frontend

Note: it's surprisingly difficult to get a slow query in a normal sized Tempo. To makes this easier to test you might want to introduce a time.Sleep(5 * time.Second) somewhere in the query path.

Expected behavior

I'd expect to see the usual logline, but with status=499.

Additional Context

The log line is printed here:

tempo/modules/frontend/handler.go

Lines 96 to 104 in ba93a40

	level.Info(f.logger).Log(
	"tenant", orgID,
	"method", r.Method,
	"traceID", traceID,
	"url", r.URL.RequestURI(),
	"duration", time.Since(start).String(),
	"response_size", contentLength,
	"status", statusCode,
	)

I believe we should not return early when the request fails:

tempo/modules/frontend/handler.go

Lines 67 to 76 in ba93a40

	resp, err := f.roundTripper.RoundTrip(r)
	if err != nil {
	writeError(w, err)
	return
	}
	if resp == nil {
	writeError(w, errors.New("nil resp in ServeHTTP"))
	return
	}

[wperron]

Hi 👋 I'll take a look

[josephwoodward]

@wperron Are you still working on this? I'm looking for an issue to pick up so happy to take a look if you've been unable to find the time?

[wperron]

@wperron Are you still working on this? I'm looking for an issue to pick up so happy to take a look if you've been unable to find the time?

I was planning and getting to it this week but feel free to take a look if you want!