webpack.server.js

const _ = require('lodash')
const path = require('path')
const webpack = require('webpack')
const nodeExternals = require('webpack-node-externals')

const PROD = !process.env.WEBPACK_DEV
const BUILD_DIR = '/build/'
const BUILD_PATH = path.join(process.cwd(), BUILD_DIR)

process.env.BABEL_ENV = 'server'

module.exports = _.pickBy({
  target: 'node', // in order to ignore built-in modules like path, fs, etc.
  externals: [nodeExternals()], // in order to ignore all modules in node_modules folder
  mode: PROD ? 'production' : 'development',
  devtool: 'source-map',
  entry: {
    server: ['@babel/polyfill', './server.js']
  },
  output: {
    path: BUILD_PATH,
    filename: PROD ? '[name].js' : '[name].dev.js'
  },
  module: {
    rules: [
      {
        test: /\.js?$/,
        loader: 'babel-loader'
      }
    ]
  },
  resolve: {
    extensions: ['.server.js', '.server.jsx', '.js', '.jsx', '.json']
  }
}, Boolean)