Move webpack manifest out from index chunk

Enables index chunk hash to become independent of children
chunk hashes. The manifest is inlined with every server
rendered route in production mode.

config/values.js

@@ -117,6 +117,10 @@ const values = {
   // containing details of all output files for a bundle?
   bundleAssetsFileName: 'assets.json',
 
+  // What should we name the manifest generated by chunk-manifest-webpack-plugin
+  // containing mappings for chunk ids and names?
+  bundleManifestFileName: 'manifest.json',
+
   // node_modules are not included in any bundles that target "node" as a
   // runtime (e.g.. the server bundle) as including them often breaks builds
   // due to thinks like require statements containing expressions..

internal/webpack/configFactory.js

@@ -5,6 +5,7 @@ import nodeExternals from 'webpack-node-externals';
 import path from 'path';
 import webpack from 'webpack';
 import WebpackMd5Hash from 'webpack-md5-hash';
+import ChunkManifestWebpackPlugin from 'chunk-manifest-webpack-plugin';
 
 import { happyPackPlugin, log } from '../utils';
 import { ifElse } from '../../shared/utils/logic';
@@ -233,6 +234,17 @@ export default function webpackConfigFactory(buildOptions) {
       // even though 1 or 2 may have only changed.
       ifClient(() => new WebpackMd5Hash()),
 
+      // Since chunk-manifest-webpack-plugin doesn't work with webpack-dev-server
+      // https://github.com/soundcloud/chunk-manifest-webpack-plugin/issues/26
+      // we generate manifest only in production mode.
+      // Also this optimisation is to prevent better long term caching of
+      // index chunk which can be compromised in development mode.
+      ifProdClient(() => new ChunkManifestWebpackPlugin({
+        filename: config('bundleManifestFileName'),
+        manifestVariable: 'webpackManifest',
+        inlineManifest: false,
+      })),
+
       // These are process.env flags that you can use in your code in order to
       // have advanced control over what is included/excluded in your bundles.
       // For example you may only want certain parts of your code to be

package.json

@@ -69,7 +69,7 @@
     "modernizr": "3.5.0",
     "normalize.css": "7.0.0",
     "offline-plugin": "4.8.3",
-    "pretty-error": "2.1.1",    
+    "pretty-error": "2.1.1",
     "prop-types": "15.5.10",
     "react": "15.6.1",
     "react-async-bootstrapper": "1.1.1",
@@ -98,6 +98,7 @@
     "babel-template": "6.26.0",
     "chokidar": "1.7.0",
     "css-loader": "0.28.7",
+    "chunk-manifest-webpack-plugin": "1.1.0",
     "enzyme": "2.9.1",
     "enzyme-to-json": "2.0.0",
     "eslint": "4.7.2",

server/middleware/reactApplication/ServerHTML.js

@@ -13,7 +13,10 @@ import serialize from 'serialize-javascript';
 import config from '../../../config';
 import ifElse from '../../../shared/utils/logic/ifElse';
 import removeNil from '../../../shared/utils/arrays/removeNil';
-import getClientBundleEntryAssets from './getClientBundleEntryAssets';
+import {
+  getClientBundleEntryAssets,
+  getClientWebpackManifest,
+} from './getClientBundleEntryAssets';
 
 import ClientConfig from '../../../config/components/ClientConfig';
 import HTML from '../../../shared/components/HTML';
@@ -27,6 +30,11 @@ function KeyedComponent({ children }) {
 // Resolve the assets (js/css) for the client bundle's entry chunk.
 const clientEntryAssets = getClientBundleEntryAssets();
 
+// Resolve the webpack manifest. Useful only in production mode.
+const clientWebpackManifest = process.env.BUILD_FLAG_IS_DEV === 'false' ?
+  getClientWebpackManifest() : {};
+
+
 function stylesheetTag(stylesheetFilePath) {
   return (
     <link href={stylesheetFilePath} media="screen, projection" rel="stylesheet" type="text/css" />
@@ -46,13 +54,18 @@ function ServerHTML(props) {
   const inlineScript = body =>
     <script nonce={nonce} type="text/javascript" dangerouslySetInnerHTML={{ __html: body }} />;
 
+  const webpackManifestScript = `
+    window.webpackManifest = ${JSON.stringify(clientWebpackManifest)};
+  `;
+
   const headerElements = removeNil([
     ...ifElse(helmet)(() => helmet.meta.toComponent(), []),
     ...ifElse(helmet)(() => helmet.title.toComponent(), []),
     ...ifElse(helmet)(() => helmet.base.toComponent(), []),
     ...ifElse(helmet)(() => helmet.link.toComponent(), []),
     ifElse(clientEntryAssets && clientEntryAssets.css)(() => stylesheetTag(clientEntryAssets.css)),
     ...ifElse(helmet)(() => helmet.style.toComponent(), []),
+    ifElse(process.env.BUILD_FLAG_IS_DEV === 'false')(() => inlineScript(webpackManifestScript)),
   ]);
 
   const bodyElements = removeNil([

server/middleware/reactApplication/getClientBundleEntryAssets.js

@@ -7,7 +7,21 @@ import { resolve as pathResolve } from 'path';
 import appRootDir from 'app-root-dir';
 import config from '../../../config';
 
-let resultCache;
+function getJSONFromFile(fileName) {
+  const filePath = pathResolve(
+    appRootDir.get(),
+    config('bundles.client.outputPath'),
+    `./${fileName}`,
+  );
+
+  if (!fs.existsSync(filePath)) {
+    throw new Error(
+      `We could not find the "${filePath}" file. Please ensure that the client bundle has been built.`,
+    );
+  }
+
+  return JSON.parse(fs.readFileSync(filePath, 'utf8'));
+}
 
 /**
  * Retrieves the js/css for the named chunks that belong to our client bundle.
@@ -22,31 +36,33 @@ let resultCache;
  *     to the render logic.  Having this method allows us to easily fetch
  *     the respective assets simply by using a chunk name. :)
  */
-export default function getClientBundleEntryAssets() {
+export function getClientBundleEntryAssets() {
+  let resultCache;
+
   // Return the assets json cache if it exists.
   // In development mode we always read the assets json file from disk to avoid
   // any cases where an older version gets cached.
   if (process.env.BUILD_FLAG_IS_DEV === 'false' && resultCache) {
     return resultCache;
   }
 
-  const assetsFilePath = pathResolve(
-    appRootDir.get(),
-    config('bundles.client.outputPath'),
-    `./${config('bundleAssetsFileName')}`,
-  );
+  const clientBundleAssetsJSON = getJSONFromFile(config('bundleAssetsFileName'));
 
-  if (!fs.existsSync(assetsFilePath)) {
-    throw new Error(
-      `We could not find the "${assetsFilePath}" file, which contains a list of the assets of the client bundle.  Please ensure that the client bundle has been built.`,
-    );
+  if (typeof clientBundleAssetsJSON.index === 'undefined') {
+    throw new Error('No asset data found for expected "index" entry chunk of client bundle.');
   }
 
-  const readAssetsJSONFile = () => JSON.parse(fs.readFileSync(assetsFilePath, 'utf8'));
-  const assetsJSONCache = readAssetsJSONFile();
-  if (typeof assetsJSONCache.index === 'undefined') {
-    throw new Error('No asset data found for expected "index" entry chunk of client bundle.');
+  resultCache = clientBundleAssetsJSON.index;
+  return resultCache;
+}
+
+export function getClientWebpackManifest() {
+  let resultCache;
+
+  if (resultCache) {
+    return resultCache;
   }
-  resultCache = assetsJSONCache.index;
+
+  resultCache = getJSONFromFile(config('bundleManifestFileName'));
   return resultCache;
 }