[Question] How to get hold of service, env, trace id, span id from span

[NicklasWallgren]

How do one get hold of service, env, trace id and span id from the current span?

tracer.span implements fmt.Formatter which builds a string of the mentioned fields, but I need to get hold of a map, or struct containing the fields.

The end goal is to pass the fields to our (zap or logrus) logger, i.e

import (
  log "github.com/Sirupsen/logrus"
)
...
`log.WithFields(log.Fields{"dd.service": "<service>", "dd.env": "<env>", "dd.trace_id": <trace id>, "dd.span_id": "<span id>"})`

[NicklasWallgren]

So the following should work for TraceId and SpanId.

span, _ := tracer.SpanFromContext(c.Request.Context())
span.Context().TraceID()
span.Context().SpanID()

Do we need to pass dd.env, dd.service and dd.version as well, as mentioned in https://docs.datadoghq.com/tracing/other_telemetry/connect_logs_and_traces/go/#:~:text=dd.trace_id%2C%20dd.span_id%2C%20dd.service%2C%20dd.env?

[ajgajg1134]

I see your overall intent seems to be to connect spans to logs, we do have an integration for logrus already that may simplify that case here: https://github.com/DataDog/dd-trace-go/tree/main/contrib/sirupsen/logrus (or you can look at the source code for some inspiration on how to do something similar for zap. (And if you do and are interested in contributing it to this repository we're open to contributions! 😄 )

As for connecting the log entry to a span you should only need the trace_id and span_id.

[NicklasWallgren]

@ajgajg1134 Thanks for the reply.

Zap dosen't support logging contextual metadata yet uber-go/zap#654, but I guess I can add my own implementation.