Instrumentation.js gets called 3 times

[john-james-gh]

Verify canary release

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

Provide environment information

Operating System:
      Platform: win32
      Arch: x64
      Version: Windows 10 Home
    Binaries:
      Node: 18.16.0
      npm: N/A
      Yarn: N/A
      pnpm: N/A
    Relevant packages:
      next: 13.4.6
      eslint-config-next: 13.4.6
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.3

btw Windows version is 11 Home. Not sure why next info isn't able to identify that.

Which area(s) of Next.js are affected? (leave empty if unsure)

App directory (appDir: true)

Link to the code that reproduces this issue or a replay of the bug

/

To Reproduce

• Create instrumentaion.js as per the guide https://nextjs.org/docs/app/building-your-application/optimizing/instrumentation
• Add a console.log in the register function
• Run npm run build
• Run npm start

There should be 2-3 console.logs, seemingly register function gets called multiple times.

Describe the Bug

register function of instrumentation.js gets called multiple times. 3 times in Azure Web Services. 2 times locally.

Azure App Service logs

Expected Behavior

register function should be called only once.

Which browser are you using? (if relevant)

Chrome latest

How are you deploying your application? (if relevant)

Azure App Services - Linux Single Container but the issue happens locally too.

_NEXT-1600

[john-james-gh]

Even when using global variables to store the invoke condition, doesn't seem to work. Global variables seem to get completely wiped.

export async function register() {
  if (process.env.NEXT_RUNTIME === "nodejs") {

    console.log(global.shouldInvoke)

    if (!global.shouldInvoke) {

      global.shouldInvoke = true

      console.log("`register` function was invoked.")

      console.log(global.shouldInvoke)
    }
  }
}

That printed this

Listening on port 3000 url: http://localhost:3000
undefined
`register` function was invoked.
true
undefined
`register` function was invoked.
true

[emondpph]

Having the same issue using the app router. It seems global variables are wiped, so I can't know if the instrumentation has been called yet

[neotrow]

+1, having the same issue.

For me it's without the app router but the traditional one.

[antonio-magicschool]

+1, having the same issue.

[pawelkaliniakit]

+1, having the same issue.

[huozhi]

Hey I couldn't repro this based on the latest canary. is there a reproduction based on the latest canary that you can provide? Thanks

[danieljee]

Having the same issue for nextjs: 13.4.13.
In my case, it's called twice in both dev and prod env

[ganicus]

Is there a way to add another hook that will be called AFTER bootstrapping/setting env and wiping out globals? Would love to see the ability to patch mods and set globals.

[matejfalat]

@huozhi It runs twice if middleware.ts is used. Repro here https://codesandbox.io/p/sandbox/cool-darkness-dh2wgt

[panda-geant]

@matejfalat did you find a way to bypass this behavior ? I face the exact same issue

[mdjfs]

Having the same issue for next 14.0.3

[huozhi]

@matejfalat

From the instrumentation docs:

We call register in all environments, so it's necessary to conditionally import any code that doesn't support both edge and nodejs. You can use the environment variable NEXT_RUNTIME to get the current environment. Importing an environment-specific code would look like this:

export async function register() {
  if (process.env.NEXT_RUNTIME === 'nodejs') {
    await import('./instrumentation-node')
  }
 
  if (process.env.NEXT_RUNTIME === 'edge') {
    await import('./instrumentation-edge')
  }
}

Middleware is running based on edge runtime and page is on nodejs runtime, you could use above code to separate the instrumentation

[mdjfs]

@huozhi Yes thats true but in the example

Even when using global variables to store the invoke condition, doesn't seem to work. Global variables seem to get completely wiped.

export async function register() {
  if (process.env.NEXT_RUNTIME === "nodejs") {

    console.log(global.shouldInvoke)

    if (!global.shouldInvoke) {

      global.shouldInvoke = true

      console.log("`register` function was invoked.")

      console.log(global.shouldInvoke)
    }
  }
}

That printed this

Listening on port 3000 url: http://localhost:3000
undefined
`register` function was invoked.
true
undefined
`register` function was invoked.
true

1. Global vars are cleaned randomly
2. Instrumentation in nodejs runtime is called more than once

[thomasmillercf]

@matejfalat you are right the middleware seems to cause the second register for some reason