Merge branch '34096-allow-gdk-to-serve-webpack-from-disk' into 'master'

Enable compile-once and compile-with-DLL options for dev-server process

Closes #34096

See merge request gitlab-org/gitlab!25149

package.json

@@ -4,7 +4,7 @@
     "check-dependencies": "scripts/frontend/check_dependencies.sh",
     "block-dependencies": "node scripts/frontend/block_dependencies.js",
     "clean": "rm -rf public/assets tmp/cache/*-loader",
-    "dev-server": "NODE_OPTIONS=\"--max-old-space-size=3584\" nodemon -w 'config/webpack.config.js' --exec 'webpack-dev-server --config config/webpack.config.js'",
+    "dev-server": "NODE_OPTIONS=\"--max-old-space-size=3584\" node scripts/frontend/webpack_dev_server.js",
     "eslint": "eslint --cache --max-warnings 0 --report-unused-disable-directives --ext .js,.vue .",
     "eslint-fix": "eslint --cache --max-warnings 0 --report-unused-disable-directives --ext .js,.vue --fix .",
     "eslint-report": "eslint --max-warnings 0 --ext .js,.vue --format html --output-file ./eslint-report.html --no-inline-config .",
@@ -213,4 +213,4 @@
     "node": ">=10.13.0",
     "yarn": "^1.10.0"
   }
-}
+}
\ No newline at end of file

scripts/frontend/webpack_dev_server.js

+const nodemon = require('nodemon');
+
+const DEV_SERVER_HOST = process.env.DEV_SERVER_HOST || 'localhost';
+const DEV_SERVER_PORT = process.env.DEV_SERVER_PORT || '3808';
+const STATIC_MODE = process.env.DEV_SERVER_STATIC && process.env.DEV_SERVER_STATIC != 'false';
+const DLL_MODE = process.env.WEBPACK_VENDOR_DLL && process.env.WEBPACK_VENDOR_DLL != 'false';
+
+const baseConfig = {
+  ignoreRoot: ['.git', 'node_modules/*/'],
+  noUpdateNotifier: true,
+  signal: 'SIGTERM',
+  delay: 1000,
+};
+
+// run webpack in compile-once mode and watch for changes
+if (STATIC_MODE) {
+  nodemon({
+    exec: `rm -rf public/assets/webpack ; yarn run webpack && exec ruby -run -e httpd public/ -p ${DEV_SERVER_PORT}`,
+    watch: [
+      'config/webpack.config.js',
+      'app/assets/javascripts',
+      'ee/app/assets/javascripts',
+      // ensure we refresh when running yarn install
+      'node_modules/.yarn-integrity',
+    ],
+    ext: 'js,json,vue',
+    ...baseConfig,
+  });
+}
+
+// run webpack through webpack-dev-server, optionally compiling a DLL to reduce memory
+else {
+  let watch = ['config/webpack.config.js'];
+
+  // if utilizing the vendor DLL, we need to restart the process when dependency changes occur
+  if (DLL_MODE) {
+    watch.push(
+      'config/webpack.vendor.config.js',
+      // ensure we refresh when running yarn install
+      'node_modules/.yarn-integrity',
+      'package.json',
+      'yarn.lock',
+    );
+  }
+  nodemon({
+    exec: 'webpack-dev-server --config config/webpack.config.js',
+    watch,
+    ...baseConfig,
+  });
+}
+
+// print useful messages for nodemon events
+nodemon
+  .on('start', function() {
+    console.log(`Starting webpack webserver on http://${DEV_SERVER_HOST}:${DEV_SERVER_PORT}`);
+    if (STATIC_MODE) {
+      console.log('You are starting webpack in compile-once mode');
+      console.log('The JavaScript assets are recompiled only if they change');
+      console.log('If you change them often, you might want to unset DEV_SERVER_STATIC');
+    }
+  })
+  .on('quit', function() {
+    console.log('Shutting down webpack process');
+    process.exit();
+  })
+  .on('restart', function(files) {
+    console.log('Restarting webpack process due to: ', files);
+  });