css-modules require hook for node. via https://github.com/css-modules/css-modules/issues/13

index.js

import setupCSS from './load-css-require.js'

setupCSS(__dirname, (err) => {
  if (err) throw err
  require('my-front-end-components-that-require-css-files.js')
})

load-css-require.js

import glob from 'glob'
import CSSLoader from 'css-modules-loader-core/lib/file-system-loader'
import path from 'path'
import async from 'async'

const EXT = '.css'

const getTokensForFile = (file, callback) => {
  // via: https://github.com/css-modules/css-modulesify/blob/abe3c8ae214ca9c690c6b1622345688affc78d17/index.js#L86-L103
  const loader = new CSSLoader(path.dirname(file))
  loader.fetch(path.basename(file), '/')
    .then((tokens) => {
      callback(null, tokens)
    })
    .catch(callback)
}

const enableCssRequireForFiles = (files, callback) => {
  const tokenMap = require.extensions[EXT] && require.extensions[EXT].tokenMap || new Map()
  // hack require so that css files can be required
  require.extensions[EXT] = (module, file) => {
    module.exports = tokenMap.get(file)
  }
  require.extensions[EXT].tokenMap = tokenMap

  async.map(files, getTokensForFile, (err, tokensForFiles) => {
    if (err) return void callback(err)

    tokensForFiles.forEach((tokensForFile, i) => {
      tokenMap.set(files[i], tokensForFile)
    })

    callback()
  })
}

export default (componentDir, callback) => {
  glob(path.join(componentDir, `**/*${EXT}`)
    // we don't need to sort, just go
    , {nosort: true}
    , (err, files) => {
      if (err) callback(err)
      else enableCssRequireForFiles(files, callback)
    }
  )
}