How to log extra field (baggage) using Logback?

[asarkar]

Along with trace and span ids, I'd also like to log an internal request identifier for each log item. Please update the instructions here specifying whether this is possible, and if yes, how to do it.
Another option is to be able to use a custom trace id.

[trask]

hey @asarkar, can you give us a specific example of an internal request identifier that you would like to include in the log?

[asarkar]

@trask It's usually a Java UUID. We have legacy systems that use a homegrown distributed tracing mechanism, and rely on this id being passed around. I'm using OTEL in a new project, but I need to be able to link to the calls made by the legacy system using the internal id.

For all intents and purposes, the internal id is equivalent to an OTEL trace id (and hence, if it's possible to use it as a custom trace id, that'll work just as well).

[trask]

are you looking to pass the UUID around via OpenTelemetry Context / Baggage, and then attach to MDC via something like a scope listener?

[asarkar]

I'm not aware of scope listeners, but your description sounds about right. In plain English, I just want to see the internal id being logged for every line of log that logs OTEL trace and span, so that I can search for it in Kibana.

The only way to create an OpenTelemetry scope listener currently is by creating a class with a very special name io.grpc.override.ContextStorageOverride. This seems like a very odd public API surface that we are exposing

Your comment open-telemetry/opentelemetry-java#922 (comment) makes me nervous; would you happen to have any examples of using the scope listener?

[trask]

Ya, we don't have that support yet, but working towards it.

@anuraaga this is a good context interop use case, being able to write a scope listener in application, and receiving callbacks when scope is changed by the javaagent

[anuraaga]

I think this sounds like it should be saved as a custom attribute on the Span and we should support populating Span attributes into logs in a configurable way.

Something Armeria has that I didn't get to yet ;)

[asarkar]

Do you’ve any examples/docs showing how to add additional fields to a trace/span? If I’m not wrong, those are called baggage.

[asarkar]

@anuraaga @iNikem Now that the 2 GA versions are out, can you comment on where this might fit in the roadmap?

[trask]

hey @asarkar, we may not have an ideal solution for this until the OpenTelemetry logs specification is completed.

In the meantime, can you write your own logback appender similar to OpenTelemetryAppender.java?

[asarkar]

@trask The UUID is either sent by the client as a HTTP request header, or we generate it if not present. Looking at the code of OpenTelemetryAppender, it's not clear to me how such a class would get hold of the UUID. From the discussion above, I got the impression that adding custom attribute to a span is not supported.

[trask]

can you put the UUID into the OTel Context? then you can read it from the OTel context in your logback appender

[josephearl]

I have I think a similar need. Currently services at my organisation are using a custom X-Some-Trace-ID header.

We'd like this header to be 1) added the logging context/MDC much like traceId is and 2) propagated to remote services.

This would allow us to incrementally adopt OpenTelemetry.

Basically I'd like what Spring Cloud Sleuth provides with the spring.sleuth.baggage.remote-fields and spring.sleuth.baggage.correlation-fields.