As discussed on Slack yesterday --

One of the things that service-template-node tried to do for clients was make it easy for them to propagate internal headers used to trace top-level user queries through the stack.

Historically the header needing propagation to any "sub-requests" made on behalf of the incoming request to your microservice was just x-request-id (which is very underdocumented btw, and we should fix this; see also T320556). Nowadays we also use and wish to propagate the W3C-standard headers traceparent and tracestate, which are used by our distributed tracing implementation.

As a minimal feature it would be helpful if service-utils had a utility function extractTraceContext() or something, which would take a map of request headers, and return header values that should be set on any outgoing request. For now, just the three headers listed above.

As a really cool stretch version of this it would be neat to look at enabling OpenTelemetry auto-instrumentation, and also perhaps write a tiny custom Propagator implementation for x-request-id, so we could use the auto-instrumentation mechanism for propagating both.