feat(nodejs): minimize out-of-the-box supported propagators to reduce coldstart delay

[serkan-ozal]

and additionally, this PR

• drops @opentelemetry/sdk-trace-node to be not dependent to the @opentelemetry/propagator-b3 and @opentelemetry/propagator-jaeger propagator packages.
• and so (as a result of dropping @opentelemetry/sdk-trace-node dependency) expands the required types can be passed to the configureTracerProvider and configureTracer functions. Since this is type expansion, it should not break backward compatibility, because lower types (NodeTraceProvider and NodeTracerConfig) can still be passed to these functions as is.

[pragmaticivan]

Could you clarify why the default propagators will not match the ones listed here? https://github.com/open-telemetry/opentelemetry-lambda/blob/main/nodejs/packages/layer/scripts/otel-handler#L12

Also if the defaults are already set in otel-handler, is there any reason to also set it here? (I actually prefer that to be here instead)

[serkan-ozal]

@pragmaticivan Because this is the existing behavior.

Currently, propagators are taken from here in the @opentelemetry/auto-configuration-propagators package and hence I used the impl/logic there.

[pragmaticivan]

But the defaults of this project are tracecontext,baggage,xray instead. This env variable will always be overwritten by that file, so the code will never hit that block

[serkan-ozal]

• without this PR, default propagators (tracecontext,baggage,xray) are set by the otel-handler script
• with this PR, still default propagators (tracecontext,baggage,xray) are set by the otel-handler script

So, this keeps the existing behavior. No need to put the same default list into the newly introduced getPropagator method too. otel-handler script is responsible for setting the defaults.

[serkan-ozal]

I really don't understand the issue here. This PR keeps the existing behavior for propagators by default because it uses the existing impl code. Why it was OK before, and NOT OK now?

[pragmaticivan]

I guess you are trying to replicate the other package behavior here when you might not need this code block. All good, though. I understand that this was the default from the other package, yet this is a block of code that will never be able to be reached in this package, which makes it dead code out of the gate

[serkan-ozal]

No one can guarantee that this is dead code even though otel-handler is in place.

Because users might put their own initializers and activate it through the NODE_OPTIONS env var. And in this case, their initializers will run before our wrapper. So, potentially, they can clear the OTEL_PROPAGATORS env var in their initializer code, hence wrapper should take care of empty OTEL_PROPAGATORS env var too.

[pragmaticivan]

Makes sense, I guess I see the point of this code, but don't see the point of keeping that code in otel-handler 😂

[serkan-ozal]

If you are still interested in removing that code block, you can send another PR for it and we can discuss. But the main point of this PR is dropping b3 and jaeger propagator dependencies without changing existing behavior.