Invalid "Native Node.js APIs are not supported in the Edge Runtime" error message

Verify canary release

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

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 19.6.0: Tue Feb 15 21:39:11 PST 2022; root:xnu-6153.141.59~1/RELEASE_X86_64
Binaries:
  Node: 16.14.0
  npm: 8.3.1
  Yarn: 1.22.17
  pnpm: N/A
Relevant packages:
  next: 12.1.6-canary.3
  react: 18.0.0
  react-dom: 18.0.0

What browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

Describe the Bug

When there is a page like the following, next build shows the error message > Native Node.js APIs are not supported in the Edge Runtime. Found "child_process" imported, on index., even when there is no middleware used.

import { spawn } from 'child_process';

export default function Page() {
  return <div>ok</div>
}

This is the same for the compilation error using next dev.

Also, a related problem, but when you use react version 17, this message is NOT shown for middleware importing child_process.

Expected Behavior

The error message is shown only for edge functions certainly, even with older react version.

To Reproduce

Import the child_process module on a page, without middleware, with react@18.

[CGamesPlay]

Apologies for commenting here, but @marek-hanzal’s issue is also my issue and I was able to solve it.

The “edge runtime” is a third webpack config that Next is using. This means that to add an extra entry to your webpack config, you need to use the nextRuntime hidden option (it should be documented here but isn’t yet). The following seems to work for me:

  webpack: (config, { nextRuntime }) => {
    // Undocumented property of next 12.
    if (nextRuntime !== "nodejs") return config;
    return {
      ...config,
      entry() {
        return config.entry().then((entry) => ({
          ...entry,
          cli: path.resolve(process.cwd(), "lib/cli.ts"),
        }));
      },
    };
  },

To explain, this function gets called with isServer: false once, then isServer: true, nextRuntime: 'nodejs', then with isServer: true, nextRuntime: 'edge'. The third call is for the edge server bundle.

[nkzawa]

To clarify, basically you cannot use Node.js modules on middleware (edge functions), so it’s expected that fs or any other modules don’t work. tho Some node.js modules MIGHT work if they don’t use node.js specific APIs.

This issue is about displaying the error message on wrong conditions.