General environment configuration

[dyladan]

Implement the general environment variable specification

Please use the getEnv('NAME') function exported by core instead of directly using process.env.NAME.

https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/sdk-environment-variables.md#general-sdk-configuration

[jtmalinowski]

Like I said in the original issue, I'm in progress on this.

[jtmalinowski]

Outstanding changes as of now:

• OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG - I have a fairly complete implementation of this in a draft somewhere, just needs to be rebased
• OTEL_SPAN* limits are incorrect versus spec, changing them at the rc stage is the best way to go, so new default limits kick in in 1.0 - very small change, I can do it
• OTEL_TRACES_EXPORTER - kind of tricky, default is otlp for which JSON (aka web) support is experimental, so doesn't seem suitable for 1.0 (Exporter environment configuration #1676)
• OTEL_METRICS_EXPORTER - as far as I remember, not planned for 1.0, is that correct?
• OTEL_EXPORTER_ZIPKIN_ENDPOINT - very straightforward

Overall I think it's doable next week provided that we'll be able to review the code somewhat quickly. I'm saying, because I've been told there was a discussion about 1.0 during last SIG.

[jtmalinowski]

@dyladan @vmarchaud should we discuss above in SIG this week or maybe you're able to decide right away?

[vmarchaud]

I've linked #1676 for the OTEL_TRACES_EXPORTER since it was the original issue

OTEL_METRICS_EXPORTER - as far as I remember, not planned for 1.0, is that correct?

Yep, we only target tracing GA for now

OTEL_SPAN* limits are incorrect versus spec, changing them at the rc stage is the best way to go, so new default limits kick in in 1.0 - very small change, I can do it

As i see, its only the default values that are incorrect right ? If so thats indeed quite straitforward. I could do it tomorrow since i've planned some time to work on otel (if you are okay with that)

OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG - I have a fairly complete implementation of this in a draft somewhere, just needs to be rebased

Did you already opened a PR for this (can't find anything right now) ? Would be welcome if you do so we can start rewiewing it !

@dyladan @vmarchaud should we discuss above in SIG this week or maybe you're able to decide right away?

I think if we could open all PRs before the SIG that would be really great, maybe merge somes and make a first SDK RC if everything looks good

EDIT:

OTEL_EXPORTER_ZIPKIN_ENDPOINT - very straightforward

I'll do this too