Clarification on `OTEL_SDK_DISABLED`

[kaylareopelle]

The spec for OTEL_SDK_DISABLED is a little vague to me. Can someone help clarify the scope?

Here's the description:

Boolean value. If “true”, a no-op SDK implementation will be used for all telemetry signals. Any other value or absence of the variable will have no effect and the SDK will remain enabled. This setting has no effect on propagators configured through the OTEL_PROPAGATORS variable.

This came up because Ruby received a PR to implement this environment variable, but we're not sure how far the functionality needs to go. The PR as it stands would skip creating providers through configuration, but someone could still manually create functional providers and tracers/meters/loggers. Is that acceptable?

I took a look at open-telemetry/opentelemetry-python#3648, and it seems like they always return no-ops when OTEL_SDK_DISABLED is true.

However, Java's implementation seems closer to the Ruby PR. Configuration is skipped, but I don't know enough about Java to know if that means you cannot create working tracers, etc.

[kaylareopelle]

Whoops, wrong repo... closing and will reopen in the specification repo