The instrumentation hook is only called after visiting a route

[daveyjones]

Link to the code that reproduces this issue

https://github.com/daveyjones/nextjs-instrumentation-bug

To Reproduce

git clone [email protected]:daveyjones/nextjs-instrumentation-bug.git
cd nextjs-instrumentation-bug
npm install
npm run dev # The register function IS called
npm run build && npm start # The register function IS NOT called until you visit http://localhost:3000

Current vs. Expected behavior

The register function should be called automatically after running npm run build && npm start. You should not have to visit a route for the function to run.

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.1.0: Mon Oct  9 21:28:12 PDT 2023; root:xnu-10002.41.9~6/RELEASE_ARM64_T8103
Binaries:
  Node: 20.9.0
  npm: 10.2.4
  Yarn: 1.22.19
  pnpm: N/A
Relevant Packages:
  next: 14.0.5-canary.29
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0
  typescript: 5.3.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

App Router

Additional context

This behavior is also reported in the comments of #49897 (reference). However, since #49897 is focused on standalone mode (which is not a factor here), I felt it was best to create a separate issue. It may be the case that resolving this issue will also resolve #49897.

_NEXT-2738

[ships]

I arrived at this issue after knocking my head on a related problem, but which turns out to be different -- leaving comment here for other seekers.

My issue was that instrumentation hooks were not running at all in a docker context (without standalone) even though they were running on next start locally.

next build puts the instrumentation hook into the built directory, but still relies on next.config.js to specify the experimental flag for those hooks to run. In my context I had copied the build directory into my docker image but left next.config.js behind.

After keeping next.config.js around, I was able to get the hooks running, but they still run only once requests are received. However, I don't have the issue of it happening repeatedly -- register are only invoked on the first API route handled.

[anuraags]

This is actually a pretty major bug that took me a while to debug. I had to create a copy of my next.config.js into next.prod.config.js that is loaded into the docker context just to get my instrumentation working.

I have no issue with running the register function for every request, but I think the running of the instrumentation should be baked into the next build step.

[github-actions]

This closed issue has been automatically locked because it had no new activity for 2 weeks. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.