Otel support

[oldbettie]

This is a copy of my conversation in discord but I believe this is a big enough deal to create an issue.

Has anyone got Otel working based on this https://nextjs.org/docs/app/building-your-application/optimizing/open-telemetry

I have wasted days now, I have it working locally with SST but the moment I deploy it I get nothing. I have even done a minrepro to test it with the latest version of SST and it still does not work in any SST remote deployment. I have the min repro working with Vercel, Railway and even self hosted in AWS ecs/ecr.
I love SST but this is a deal breaker for me. I have tried both manual and auto instrumentation. I am not running a collector I am just using honeycomb traces endpoint as it doesn't require a collector.

I have load tested it in railway and it performs exactly as expected.

Is this something open-next plans to sortout or should I just switch to Railway or Vercel? How do people in production currently deal with Otel? surely this has been raised before but I have searched high and low and could not find anything. This tells me either no one deploys to prod with with SST...

[conico974]

This tells me either no one deploys to prod with with SST...

Not everyone use Otel. Otel is considered as EXPERIMENTAL by Next themselves, that's not exactly something that i would consider mandatory to deploy in prod

Here is a link to the discord thread for context https://discord.com/channels/983865673656705025/1286983198819090445

This is the context used by vercel in their runtime https://github.com/vercel/otel/blob/main/packages/otel/src/vercel-request-context/api.ts

One other option (probably a better one now that i think about it) to implement this would be to use a custom wrapper and provide a fake vercel context yourself https://open-next.js.org/config/custom_overrides
Something like that (not tested) should do the trick, but be aware that this is a bit risky. It relies on internal stuff from vercel which might change in the future :

// customWrapper.ts
import streamingWrapper from 'open-next/wrappers/aws-lambda.js'
import {WrapperHandler} from 'open-next/types/open-next.js'
 
const handler : WrapperHandler = async (handler, converter) => {
  const defaultHandler = await streamingWrapper.wrapper(handler, converter)
  return async (event, context) => {
    const symbol = Symbol.for("@vercel/request-context");
    const promiseToAwaits : Promise<unknown>[] = []

    //@ts-ignore
    globalThis[symbol] = {
      get: () => {
        return {
          waitUntil: (promiseOrFunc: Promise<unknown> | (() => Promise<unknown>)) => {
            const promise = 'then' in promiseOrFunc ? promiseOrFunc : promiseOrFunc()
            promiseToAwaits.push(promise)
          },
          headers: event.headers,
          url: event.rawPath,
        }
      }
    }
    const response = await defaultHandler(event, context)
    await Promise.all(promiseToAwaits)
    return response
  }
}
 
export default {
  wrapper: handler,
  name: "aws-lambda",
  supportStreaming: false,
};

[khuezy]

This tells me either no one deploys to prod with with SST...

[jonlambert]

Not everyone use Otel. Otel is considered as EXPERIMENTAL by Next themselves, that's not exactly something that i would consider mandatory to deploy in prod

Disagree here FWIW - it's no longer regarded as experimental by Next.js, and OpenTelemetry is definitely something a lot of companies will expect to be supported in a deployment.