How to add trace_id to logger metadata

[btkostner]

For some background, I am currently using opentelemetry with Elixir and exported to datadog via dd-agent. It's working great and everything tracing wise just works ™️. All traces show up in datadog with an otel.trace_id attribute, but datadog expects log messages to also have that trace_id to correlate between the two. So my question is, what is the best way to add the trace_id in Logger.metadata?

[tsloughter]

I'm working on a useful response. I first have to get all the lost context from the discussions we've had about this back into my head because I can't find where it was written down :)

I think we decided on adding functionality in otel that updates the logger process metadata when a span is started with the tracer macros.

But there may also be a way to do it with logger_filters that wouldn't require updates to opentelemetry.

Will get back to you later today.

[tsloughter]

Oh, @bryannaegele just pointed me to most of the existing context of our discussions! salemove/opentelemetry_logger_metadata#2 (comment)

This also points to a way you can easily do it today by just using that application since you are using Elixir.

Looks like from my last message there I was pushing for not going the filter or OnStart processor route and instead adding it when the macro to start an active span is called. I should be able to get a PR for that done today or tomorrow. I think the biggest question on that will be if we need to have an option to enable/disable it.

[bryannaegele]

I think we need to also handle it in context attach/detach and not just the macros.

[tsloughter]

Ah right right

[tsloughter]

Looks like the only place it needs to be added is in attach and detach since that is what gets used by with_span.

[tsloughter]

Opened a PR #394