[BUG] Issues correlating logs with traces with Google Cloud Run Serverless Env

[Vlaquit]

Hello, I'm trying to instrument my Cloud Run (google serverless) but I can't get the logs to correlate with the traces.

Describe what happened:
I have tried several options such as using this small library in contrib with logrus.
https://github.com/DataDog/dd-trace-go/blob/main/contrib/sirupsen/logrus/logrus.go
And the log does not show the same dd.trace_id than the traces UI.
Like on this picture:

What I find suspicious is that the trace_id seems very similar, so it can't come from a completely different trace in the code because if I've understood correctly it's randomly generated in the dd-trace lib.
In addition, I have the feeling that this ID is rounded off to end with ...00

Steps to reproduce the issue:
As I said, I've tried using bot DDContextLogHook library from contrib and the manual method of inserting the trace ID into the logs but I get the same result.
Here's my code snippet which I assume should work:

func (f *CloudRunFunction) SyncTransferJobs(w http.ResponseWriter, r *http.Request) {
	// ...
	span, ctx := tracer.StartSpanFromContext(
		r.Context(),
		OperationType,
		tracer.ResourceName(funcName),
		tracer.Tag("fileName", fileName),
	)
	defer func() { span.Finish(tracer.WithError(err)) }()
	logEntry := f.logEntry.WithFields(logrus.Fields{
		"function":    "sync_transfer_jobs",
		"dd.trace_id": span.Context().TraceID(),
		"dd.span_id":  span.Context().SpanID(),
	})

	logEntry.Info("Initializing cloud run function")

	// ...
}

I have logrus configured with the json formatter with this logger.SetFormatter(&logrus.JSONFormatter{})

Additional environment details (Version of Go, Operating System, etc.):
I am using go 1.19
The golang:1.19-buster Docker image

[Vlaquit]

Here's the result of another test I did:

The code:

func (f *CloudRunFunction) SyncTransferJobs(w http.ResponseWriter, r *http.Request) {
	// ...
	logEntry := f.logEntry.WithFields(logrus.Fields{
		"function":    "sync_transfer_jobs",
		"dd.trace_id": span.Context().TraceID(),
		"dd.span_id":  span.Context().SpanID(),
	})

	myLog := "Span context trace id: " + strconv.FormatUint(span.Context().TraceID(), 10)
	logEntry.Info(myLog)
	// ...
}

Can this be related to an issue with logrus or the datadog remapper ?

[gondyb]

Hello @Vlaquit, I'm not sure how logrus works internally, but make sure that your trace_id is sent as a string. Json encoding in go using encoding/json may lose precision on big integers, since the conversion is internally using float64. Let me know if that fixes the issue!

[Vlaquit]

Thank you, it seems to work when I cast the TraceID to string! (BTW I forgot to check that the remapping was fine. The trace id reserved attribute remapper was not parsing the data.jsonPayload.dd.trace_id properly) 🙏🏻

However I had the same problem with the contrib/logrus lib, I think the bug could still occur when you want to use it.