Question about OTEL_SEMCONV_STABILITY_OPT_IN

[TimothyMothra]

I'm working on Semantic Conventions for Http which defines the Environment Variable OTEL_SEMCONV_STABILITY_OPT_IN as a list of comma-separated values.

How should I handle if multiple values have been set?

For example:

$env:OTEL_SEMCONV_STABILITY_OPT_IN = "http,http/dup"

What's the expected behavior?

1. Honor first value
2. Honor last value
3. Treat this as invalid and use default behavior.

[joaopgrassi]

I would see it as an invalid value, log an warning maybe and fallback to the default behavior. We should probably document this if we decide to go this route.

[pellared]

Maybe we could change the values to something like http/stable and http/legacy? The user would provide http/legacy,http/stable instead of http/dup.

[mateuszrzeszutek]

This is how we implemented that in the Java instrumentation -- I chose to just sum up the boolean values and enable everything. Even if this is technically invalid value, I think this is probably a bit gentler to the user who just wanted both options and typed all the settings.

[TimothyMothra]

I don't have a strong preference, but I think @mateuszrzeszutek approach is the most user friendly.

I fully agree with @joaopgrassi that this should be added to the documentation.
Are there any other csv configurations in OTel that could be used as precedent here?