webpack.backend.config.js

var webpack = require('webpack');
var path    = require('path');
var fs = require('fs');

var nodeModules = fs.readdirSync('node_modules')
  .filter(function(x) {
    return ['.bin'].indexOf(x) === -1;
  });

module.exports = {
  entry: [
    'babel-polyfill',
    './server/app.js'
  ],
  debug: true,
  target: 'node',
  output: {
    filename: 'backend.js',
    path: path.resolve(__dirname, 'server')

  },
  node: {
    __dirname: true,
    __filename: true
  },
  externals: [
    function(context, request, callback) {
      var pathStart = request.split('/')[0];
      if (nodeModules.indexOf(pathStart) >= 0 && request != 'webpack/hot/signal.js') {
        return callback(null, "commonjs " + request);
      };
      callback();
    }
  ],
  plugins: [
    new webpack.IgnorePlugin(/\.(css|less)$/),
    new webpack.BannerPlugin('require("source-map-support").install();',
                             { raw: true, entryOnly: false }),
    new webpack.HotModuleReplacementPlugin({ quiet: true })
  ]
};