Custom build with App getInitialProps hangs

[kinetifex]

Run next info (available from version 12.0.8 and up)

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 20.6.0: Mon Aug 30 06:12:21 PDT 2021; root:xnu-7195.141.6~3/RELEASE_X86_64
Binaries:
  Node: 14.18.3
  npm: 6.14.15
  Yarn: 1.22.10
  pnpm: N/A
Relevant packages:
  next: 12.0.8
  react: 17.0.2
  react-dom: 17.0.2

What version of Next.js are you using?

12.0.8

What version of Node.js are you using?

14.18.3

What browser are you using?

N/A

What operating system are you using?

macOS

How are you deploying your application?

next build

Describe the Bug

We have found a bug when using Next 12 with Gasket. When the custom _app uses getInitialProps, the process hangs and never finishes.

This is reproducable with a very simple custom build script, such as in this repo.

When calling the Next build function from a script, the process hangs and never exits.

Expected Behavior

Running a build by executing the next/dist/build function from a script completes and exits successfully.

To Reproduce

Clone this repo, and run the custom build script.

git clone git@github.com:kinetifex/next-12-custom-build-bug.git
cd next-12-custom-build-bug
yarn
yarn custom-build

[balazsorban44]

I don't think we document this being a supported use case, but the issue seems to be that you have to exit the process yourself.

const path = require("path")
const builder = require("next/dist/build").default

async function main() {
  // Do some setup, then gather some config - such as from Gasket plugins
  const config = {}
  try {
    await builder(path.resolve("."), config)
    process.exit(0)
  } catch (error) {
    console.error(error)
    process.exit(1)
  }
}

main()

should work.

[kinetifex]

This shouldn't be closed yet. We shouldn't have to exit the process manually.

My example repo has a contrived example, but with Gasket, we can perform other steps after the Next build has been completed. This has worked fine on previous versions of Next (8-11). Something introduced in Next 12 is causing this issue.

[kinetifex]

And again, it only occurs with getInitialProps on the App, indicative of a bug in related code. I'll try to do some more digging, but a manual process exit is not the solution.

[balazsorban44]

Unless we document const builder = require("next/dist/build").default somewhere, it is not supposed to be used that way, and there is no guarantee for it to work.

What you could do instead is a script that only modifies the next.config.js file first and then runs next build the regular way node my-script && next build && node some-other-script.

[github-actions]

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