express でつくられたアプリをリリース用にバンドルする webpack（express はバンドルできないようなので除外）

packgage.json

{
  "name": "app",
  "version": "1.0.0",
  "description": "app",
  "repository": {},
  "license": "",
  "devDependencies": {
    "@babel/core": "^7.9.0",
    "@babel/preset-env": "^7.9.0",
    "babel-loader": "^8.1.0",
    "webpack": "^4.42.1",
    "webpack-cli": "^3.3.11"
  },
  "dependencies": {
    "express": "^4.17.1",
    "log4js": "^6.1.2"
  },
  "scripts": {
    "start": "node src/app.js",
    "debug": "node --inspect=0.0.0.0 src/app.js",
    "build": "webpack",
    "server:start": "npm run build && node dist/app-bundle.js",
    "server:debug": "node --inspect=0.0.0.0 dist/app-bundle.js"
  }
}

webpack.config.js

const path = require('path');

module.exports = {
  devtool: "source-map",
  mode: 'production',
  target: 'node',
  // use express in server install (npm install express on server)
  externals: function (context, request, callback) {
    if (request === 'express') {
      return callback(null, 'commonjs ' + request);
    }
    callback();
  },
  entry: {
    app: './src/app.js',
  },
  output: {
    filename: 'app-bundle.js',
    path: path.join(__dirname, '/dist'), // eslint-disable-line
  },
  optimization: {
    minimize: false
  },
  plugins: [
  ],
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: [{
          loader: 'babel-loader',
          options: {
            presets: [[
              '@babel/preset-env', {
                "targets": {
                  "node": "current"
                }
              }
            ]]
          }
        }]
      }
    ]
  },
  resolve: {
    extensions: ['.js'],
    modules: [
      "node_modules"
    ]
  },
  performance: {
    hints: false
  }
};