Add instrumentation for `fetch` API

[david-luna]

Add instrumentation for `fetch` API

[david-luna]

@djMax thanks on answering on the question about donating the implementation of https://github.com/gas-buddy/service/blob/main/src/telemetry/fetchInstrumentation.ts to this repo.

This is the issue we're using to track it's progress. As discussed in the JavaScript SIG (see Dec 13 notes) the goal would be to have a new package named @opentelemetry/instrumentation-undici which will serve to instrument undici package and also the global fetch API. This new package would be placed within experimental/packages folder along with HTTP & GRPC instrumentations.

Tasks to be done

• Port the code
• Create tests for global fetch
• Create tests for undici package
• Add documentation

I can create a draft PR to start so you can give a 1st review or we could do it the other way around. Up to you. :)

[djMax]

Happy to review a PR, and to try it out in a place with tests that verify it's function from a consumer perspective.

[david-luna]

@dyladan @pichlermarc could you assign this one to me? Thanks :)

[trentm]

@david-luna Perhaps clarify that this is about Node.js's global fetch(). IIUC https://github.com/open-telemetry/opentelemetry-js/tree/main/experimental/packages/opentelemetry-instrumentation-fetch/ instruments fetch() for web usage. I wonder if that instrumentation might be close to also being able to instrument Node.js's fetch(). When enabled it shims globalThis.fetch. That said, the undici diagnostics_channel events from Node's implementation of fetch() might provide more interesting details for tracing.

[david-luna]

yeah, it was very short. I've updated with more info :)

[david-luna]

I've reached the dev who shared his fetch implementation in the same conversation
#3346 (reply in thread)

I've try another channel if there is no answer in few days

[trentm]

This was discussed in the OTel JS SIG today (https://docs.google.com/document/d/1tCyoQK49WVcE-x8oryZOTTToFm7sIeUhxFPm9g-qL1k/edit#heading=h.ry29ajruzxyg). It was concluded to move this instrumentation to the contrib repo.

[david-luna]

Link to the contrib PR: open-telemetry/opentelemetry-js-contrib#1951