Injecting span context using SpanContext instead of Context

[Deeds67]

Hi, the old opentracing-api's inject signature supported injecting a SpanContext:

<C> void inject(SpanContext spanContext, Format<C> format, C carrier);

The new signature only takes a Context:

<C> void inject(Context context, @Nullable C carrier, TextMapSetter<C> setter)

Since I'm passing SpanContext on MDC (Using Scala with monix task and monix-mdc. I don't think thread based context propagation will work), I'm not using Context at all, but it seems like the new opentelemetry API doesn't allow me to inject span context using SpanContext anymore. Is there a plan to support this?

[jkwatson]

You can put your SpanContext into a Context today like this (perhaps not the most obvious API, we know):

context.with(Span.wrap(spanContext))

[Deeds67]

Thanks for the response.

Is it possible to avoid Context completely? I'm manually passing the SpanContext because Context looks like it uses ThreadLocal and I think Monix Task doesn't support this out of the box. At least I haven't investigated much into why it's not working, but I prefer as an initial approach to just manually pass the SpanContext. The old opentracing api allowed this, is there still a way to do this?

[jkwatson]

In OpenTelemetry, Context is the unit of propagation, not SpanContext, so you can't avoid creating a Context instance to do this, no. If you never make your Context "current", then no ThreadLocal will be involved.

[Deeds67]

Thank you very much for the assistance. This has solved my problem 👍