Global context & data is lost between custom server and Next.js router/renderer

[coltonehrman]

Verify canary release

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

Provide environment information

    Operating System:
      Platform: linux
      Arch: x64
      Version: #1 SMP PREEMPT_DYNAMIC Sun Aug  6 20:05:33 UTC 2023
    Binaries:
      Node: 16.17.0
      npm: 8.15.0
      Yarn: 1.22.19
      pnpm: 7.1.0
    Relevant Packages:
      next: 13.4.20-canary.12
      eslint-config-next: N/A
      react: 18.2.0
      react-dom: 18.2.0
      typescript: 5.1.3
    Next.js Config:
      output: N/A

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

App Router, Data fetching (gS(S)P, getInitialProps), Middleware / Edge (API routes, runtime), Standalone mode (output: "standalone")

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

https://codesandbox.io/p/sandbox/relaxed-phoebe-jncmvg

To Reproduce

1. Use next version 13.4.13 or higher
2. Setup a custom server.
3. Use nconf (a singleton module)
4. Modify nconf store in custom server.
5. Try to access the modified nconf object in Next.js context. (ie: pages/, app/, gSSP, API route, etc.)

Describe the Bug

All global context and data is lost between the custom server context and the Next.js context.

As you can see below, the global (singleton) module was cached and worked across the custom server and Next.js gSSP in 13.4.12, but doesn't work in versions 13.4.13 or higher.

Custom server code

Next.js 13.4.12

Next.js 13.4.19

Link to related issue:

• Extending request while using a custom server/standalone mode #54440

Expected Behavior

Global data stays intact between both contexts.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

[danieljee]

I don't know if this is a similar issue but a singleton module loses context in every request in route handlers. It gets reinstantiated every time.

[shaunwarman]

We think the fix is to leverage
https://nextjs.org/docs/app/api-reference/next-config-js/serverComponentsExternalPackages

[coltonehrman]

Resolved with #54782 (comment)

[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.