Zero-code `OTEL_` support

[robross0606]

We're trying to figure out which (if any) "zero code" configuration is supported by the JS library and available information seems very confusing. For example, there are pages that show OTEL_EXPORTER_OTLP_TRACES_ENDPOINT, OTEL_SERVICE_NAME and/or OTEL_SDK_DISABLED is supported and then other pages which claim limited or no support, which contradicts other examples and pages. Is there some definitive list of which zero code configuration options are supported by the Javascript library for Node.js use?

[dyladan]

The first link is a getting started guide for JS which is not comprehensive. The second link is the specification which includes all environment variables defined by the project regardless of their support in any given language. Generally implementations follow that list, but some may not be implemented yet. The only truly definitive list is in the code https://github.com/open-telemetry/opentelemetry-js/blob/main/packages/opentelemetry-core/src/utils/environment.ts#L88

Environment variable use is spread among many packages which each have their own documentation, but I don't think there is a centralized list of supported environment variables.

[robross0606]

Is there an example anywhere of how to actually leverage these environment variables? All the examples appear to use programmatic initialization which I would think overrides things like OTEL_EXPORTER_OTLP_ENDPOINT.

[robross0606]

Specifically, we are having no luck getting OTEL_SERVICE_NAME to work. We have confirmed it is set on the environment, but traces continue to come into our OTEL collector as "unknown_service". If we set it programmatically that problem goes away.

[chancancode]

Hi @robross0606! I stumbled across this issue, I tried reproducing it but couldn't replicate the problem you reported (OTEL_SERVICE_NAME not working as expected).

I made a repo with a simple reproduction based on the official docs, you can use the code and steps in there to confirm my findings: https://github.com/tildeio/otel-js-demos/tree/5167-otel-service-name

Hopefully with that, you'd be able to find out what's different about your environment and fix the issue on your end. If you determined the condition/interactions that causes this to fail, feel free to provide extra details on how the reproduction can be tweaked to demonstrate the problem.

[dyladan]

This is not well documented and can for sure be improved. If you're not using the SDK package or setting up the proper resource detectors, you can get this behavior. That said, this is intended behavior if that is what is actually happening. If that's not what's happening, please provide a reproducer that we can look at. As @chancancode pointed out, the normal path is working currently. If there is no update here we will close this issue in 2 weeks.