Add webpack config for prod

Author: jtpio

app/package.json

@@ -4,7 +4,7 @@
   "private": true,
   "scripts": {
     "build": "webpack",
-    "build:prod": "webpack --mode=production",
+    "build:prod": "webpack --config ./webpack.prod.config.js",
     "clean": "rimraf build && jlpm run clean:static",
     "clean:static": "rimraf -g \"../notebook/static/!(favicons)\"",
     "watch": "webpack --config ./webpack.config.watch.js"

app/webpack.prod.config.js

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) Jupyter Development Team.
+ * Distributed under the terms of the Modified BSD License.
+ */
+
+const merge = require('webpack-merge').default;
+const config = require('./webpack.config');
+const WPPlugin = require('@jupyterlab/builder').WPPlugin;
+
+config[0] = merge(config[0], {
+  mode: 'production',
+  devtool: 'source-map',
+  output: {
+    // Add version argument when in production so the Jupyter server
+    // allows caching of files (i.e., does not set the CacheControl header to no-cache to prevent caching static files)
+    filename: '[name].[contenthash].js?v=[contenthash]'
+  },
+  optimization: {
+    minimize: false
+  },
+  plugins: [
+    new WPPlugin.JSONLicenseWebpackPlugin({
+      excludedPackageTest: packageName =>
+        packageName === '@jupyterlab/application-top'
+    })
+  ]
+});
+
+module.exports = config;