Cannot access runtime variables in middlewares

Run next info (available from version 12.0.8 and up)

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 21.2.0: Sun Nov 28 20:28:54 PST 2021; root:xnu-8019.61.5~1/RELEASE_X86_64
Binaries:
  Node: 16.13.0
  npm: 8.1.0
  Yarn: 1.22.17
  pnpm: 6.25.0
Relevant packages:
  next: 12.0.8-canary.18
  react: 17.0.2
  react-dom: 17.0.2

What version of Next.js are you using?

12.0.8-canary.18

What version of Node.js are you using?

16.13.0

What browser are you using?

Chrome

What operating system are you using?

macOS

How are you deploying your application?

Other platform

Describe the Bug

I cannot access any runtime variables inside _middleware.ts files.

Expected Behavior

I want to access runtime variables in middlewares.

I couldn’t find any documentation about this and hence can only hope that it is a bug and will be fixed. Currently I can only use process.env.FOO inside middlewares but that are build time variables, which is not ideal, because I’d prefer to use here server runtime variables.

To Reproduce

Inside _middleware.ts:

import { NextFetchEvent, NextRequest, NextResponse } from 'next/server';
import getConfig from 'next/config';

// outside the middleware export
console.log(getConfig());

// inside the middleware export (doesn't matter)
export function middleware(request: NextRequest, _event: NextFetchEvent) {
    console.log(getConfig());
    return NextResponse.next();
}
...

Always logs undefined as any runtime config seems to be not accessible in middlewares.

[fdc-viktor-luft]

However, I found an ugly workaround. At least as tip for the docs: You should mention in the “Middleware” docs that “next/config” is not working and maybe also why it is not working.

[github-actions[bot]]

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