Add custom propagator to default propagators list in node

[ssukienn]

Hi,

I wonder if there is an easy or recommended way of adding custom propagators in NodeTraceProvider to the end (or start) of the default propagators list (_registeredPropagators) using NodeSDK.

I would like to add the CloudPropagator (link) but I don't want to opt-out from spec default propagators like tracecontext, baggage, b3 etc. that still could recognize the propagated context.

Is my only option to subclass NodeTraceProvider and override _registeredPropagators? But usage of it seems to be for propagators from env. I don't use them.

const sdk = new NodeSDK({
  spanProcessor: ... // is it needed in my scenario?
  traceExporter: undefined // don't want to export
  textMapPropagator: new CompositePropagator({ propagators: [/*getDefaults without cast to get protected defaults?*/, new CustomPropagator()] })
  instrumentations: [
    getNodeAutoInstrumentations({
      '@opentelemetry/instrumentation-http': {},
      '@opentelemetry/instrumentation-pino': {},
    }),
  ],
});

My use case is that I want to allow for propagation between boundaries (http for now) and instrument the logs, but I don't care much about internal instrumentation and exporting. Just want to read the context in and propagate out.

Appreciate the help.