webpack.config.server.js

const webpack = require('webpack')
const nodeExternals = require('webpack-node-externals')
const CleanWebpackPlugin = require('clean-webpack-plugin')
const path = require('path')

module.exports = {
  mode: 'production',

  target: 'node',

  externals: [nodeExternals()],

  devtool: 'cheap-module-source-map',

  entry: [
    'babel-polyfill',
    path.resolve(__dirname, 'app.js'),
  ],

  output: {
    path: path.resolve(__dirname),
    libraryTarget: 'commonjs2',
    filename: 'handler.js',
  },

  module: {
    strictExportPresence: true,
    rules: [
      {
        oneOf: [
          {
            test: [/\.bmp$/, /\.gif$/, /\.jpe?g$/, /\.png$/],
            loader: require.resolve('url-loader'),
            options: {
              limit: 10000,
              name: 'media/[name].[hash:8].[ext]',
            },
          },
          {
            test: /\.(js|jsx)$/,
            exclude: [/node_modules/],
            loader: require.resolve('babel-loader'),
            options: {
              cacheDirectory: true,
            },
          },
          {
            exclude: [/\.(js|jsx)$/, /\.html$/, /\.json$/],
            loader: require.resolve('file-loader'),
            options: {
              name: 'media/[name].[hash:8].[ext]',
            },
          },
        ],
      },
    ],
  },

  plugins: [
    new CleanWebpackPlugin({
      cleanOnceBeforeBuildPatterns: ['handler.js', 'handler.js.map'],
    }),
  ],
}