How to manually extract context/span from incoming http request? (http, express, something else)

[krutoo]

I trying to migrate my Node.js application from jaeger-client to @opentelemetry/* packages

In my Node.js application i have a simple http server and i want to create span on each response.

With jaeger-client i did it in the following way:

import { FORMAT_HTTP_HEADERS } from 'opentracing';

// app is expressjs app
app.get('/home', req => {
  const rootSpan = tracer.startSpan('response', {
    childOf: tracer.extract(FORMAT_HTTP_HEADERS, req.headers),
  });

  // ...make child spans of rootSpan
});

I want to connect my root span of response with spans from other application, that performs request to my Node.js application server. About the same as I would do it with jaeger-client.

How can i make it? Is it possible to create child spans manually, without auto instrumentations?

[krutoo]

I get answer here: https://stackoverflow.com/a/71909958/13166471