[Feature]: OTEL_TRACES_EXPORTER support

[codefromthecrypt]

Related Problems?

Right now, I need manual code to check if OTEL_TRACES_EXPORTER is console or none, similarly for METRICS etc.

Describe the solution you'd like:

I would like OTEL_TRACES_EXPORTER, METRICS, etc to be handled in this library, so that a simple exporter is used for traces not a batched one.

Considered Alternatives

manual code

Additional Context

No response

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[scottgerring]

Hey @codefromthecrypt thanks for raising this!

The relevant bit of the spec is here - "Exporter Selection" - allowed values are otlp / zipkin / console / none for e.g. tracing. Supporting this is not required but would certainly be nice to have. We can certainly treat this part !as a feature request!

so that a simple exporter is used for traces not a batched one.
These variables are intended to be used to pick the type of exporter, but from the spec don't let us specify whether simple or batch span processor are used. I don't think we'd want to overload the meaning of the fields beyond what is in the standard. Although there are other variables for tuning e.g. the batch span processor.

Can you clarify if this is what you mean in particular, and if so, elaborate on your use case a bit - is there a reason the builder methods with_simple_exporter and with_batch_exporter are a bad fit here?

[cijothomas]

picking an exporter based on env variable requires us to have an uber crate that bundles all the exporters, and pick/activate one based on the env variable. Such crate is not in the plan now.