Context propagation not working with RxJS

[jdespatis]

Hello,

I'm testing OpenTelemetry with RxJS, which is used in Angular, NestJS for which instrumentations already exist
I'm also using auto-instrumentations-node

The fact is context doesn't seem to be propagated, maybe I'm missing something?

It works if I inject manually the context

Here is a test script to reproduce:

import { trace, context } from '@opentelemetry/api';
import { of, tap } from 'rxjs';

const tracer = trace.getTracer('example');
const logContext = (message: string) => console.log(message, context.active());
const ob = tracer.startActiveSpan('my-lib', () => {
  const ctx = context.active();

  // Context is the expected one, corresponding to 'my-lib' active span
  logContext('Before observable');

  return of(1).pipe(
    // Context is BASE_CONTEXT, not the expected one
    tap(() => logContext('In pipeline, but without context provided')),

    // Context is the expected one, corresponding to 'my-lib' active span
    tap(() => context.with(ctx, logContext, undefined, 'In pipeline, with context provided'))
  );
});

ob.subscribe();

• The first tap operator won't benefit from the active context
• the second one will benefit from it, because context is injected with context.with

Is there a smarter way to achieve this, more automatically?

This issue may affect other languages where Rx is also available RxJava, RxGo, etc..

• This only affects the JavaScript OpenTelemetry library
• This may affect other libraries, but I would like to get opinions here first