Hello! I have created a Ktor feature https://github.com/mjstrasser/ktor-features-zipkin/ that enables a Ktor app to participate in Zipkin distributed tracing. The code includes a server feature that recognises Zipkin HTTP tracing headers and a client feature that propagates headers into downstream calls. Let me know what you think, and whether it is useful to you.

have something similar for newrelic distributed tracing, I wonder if anyone interesting in publishing it as open source library

Great to hear that. I (or rather my company) use Zipkin. I will definitely try it in a while.