Register http instrumentation after server is configured but before it is started.

[pragmaticivan]

Most of the examples shows tracing functions being called with -r on nodejs, I'm trying to build a lib for NestJS but this framework might not have a way to call the instrumentation functions before server configurations are defined.

Is there a better way to do that?

[Flarna]

Could you provide some more information here how your lib should interact with NestJS? e.g.

• it calls some APIs to register hooks
• monkey patching
• ...

More or less all instrumentations available now in this repo use monkey patching.
They must be initialized on early startup, before any app code is running - before e.g. require(<framework>) is called.
They install a hook which is called when require(<framework>) is called to patch some APIs and once they are called instrumentations do whatever is needed.

e.g. for http the createServer is patched. Once application calls it the instrumenation wraps the given request listener.

I guess something similar should work for NestJs. Hooks require to start monitoring it by patching whatever is needed. I don't know the NestJs internals so cant give an exact guideline.

In general if monkey patching can be avoided by using public APIs of a package it's better do use these APIs.

[Flarna]

There seems to be ongoing work regarding NestJS: open-telemetry/opentelemetry-js-contrib#553

fyi @rauno56

[pragmaticivan]

@Flarna I've created that lib https://github.com/pragmaticivan/nestjs-otel

Currently trying to debug that issue: pragmaticivan/nestjs-otel#42