Code to put on top of `server.js` to alter behaviour of Next's internal caching

next-fs-patcher.js

const fs = require('fs')
const path = require('path')
const { patchFs } = require('@aleung/fs-monkey')

const resolveToTmp = (pathLike) => {
  const isCacheDir = pathLike.includes('.next/cache')
  if (!isCacheDir) return pathLike

  const endPath = pathLike.split('.next/cache/')[1]
  console.log('patcher.js: resolveToTmp', endPath)
  return path.join('/tmp', endPath)
}

const defaultRewrite =
  (fn) =>
  (pathLike, ...rest) =>
    fn(resolveToTmp(pathLike), ...rest)

const nextFs = {
  existsSync: defaultRewrite(fs.existsSync),
  mkdir: defaultRewrite(fs.mkdir),
  mkdirSync: defaultRewrite(fs.mkdirSync),
  readFile: defaultRewrite(fs.readFile),
  readFileSync: defaultRewrite(fs.readFileSync),
  stat: defaultRewrite(fs.stat),
  statSync: defaultRewrite(fs.statSync),
  writeFile: defaultRewrite(fs.writeFile),
  writeFileSync: defaultRewrite(fs.writeFileSync),
  rm: defaultRewrite(fs.rm),
  rmSync: defaultRewrite(fs.rmSync),

  promises: {
    mkdir: defaultRewrite(fs.promises.mkdir),
    readFile: defaultRewrite(fs.promises.readFile),
    stat: defaultRewrite(fs.promises.stat),
    writeFile: defaultRewrite(fs.promises.writeFile),
    rm: defaultRewrite(fs.promises.rm),
  },
}

patchFs(nextFs)