Move sourcegraph assets to versioned subdirectory

Also consolidates some webpack config with
shared constants

Also @markrian helped word the CHANGELOG

app/assets/javascripts/sourcegraph/index.js

@@ -17,7 +17,7 @@ export default function initSourcegraph() {
     return;
   }
 
-  const assetsUrl = new URL('/assets/webpack/sourcegraph/', window.location.href);
+  const assetsUrl = new URL(process.env.SOURCEGRAPH_PUBLIC_PATH, window.location.href);
   const scriptPath = new URL('scripts/integration.bundle.js', assetsUrl).href;
 
   window.SOURCEGRAPH_ASSETS_URL = assetsUrl.href;

changelogs/unreleased/284588-prefix-sourcegraph-url-with-version.yml

+---
+title: Make sure Sourcegraph asset always loads successfully
+merge_request: 49030
+author:
+type: fixed

config/webpack.config.js

@@ -29,9 +29,18 @@ const WEBPACK_MEMORY_TEST =
 const NO_COMPRESSION = process.env.NO_COMPRESSION && process.env.NO_COMPRESSION !== 'false';
 const NO_SOURCEMAPS = process.env.NO_SOURCEMAPS && process.env.NO_SOURCEMAPS !== 'false';
 
+const WEBPACK_OUTPUT_PATH = path.join(ROOT_PATH, 'public/assets/webpack');
+const WEBPACK_PUBLIC_PATH = '/assets/webpack/';
+const SOURCEGRAPH_PACKAGE = '@sourcegraph/code-host-integration';
+
 const VUE_VERSION = require('vue/package.json').version;
 const VUE_LOADER_VERSION = require('vue-loader/package.json').version;
 const WEBPACK_VERSION = require('webpack/package.json').version;
+const SOURCEGRAPH_VERSION = require(path.join(SOURCEGRAPH_PACKAGE, 'package.json')).version;
+
+const SOURCEGRAPH_PATH = path.join('sourcegraph', SOURCEGRAPH_VERSION, '/');
+const SOURCEGRAPH_OUTPUT_PATH = path.join(WEBPACK_OUTPUT_PATH, SOURCEGRAPH_PATH);
+const SOURCEGRAPH_PUBLIC_PATH = path.join(WEBPACK_PUBLIC_PATH, SOURCEGRAPH_PATH);
 
 const devtool = IS_PRODUCTION ? 'source-map' : 'cheap-module-eval-source-map';
 
@@ -143,7 +152,7 @@ if (VENDOR_DLL && !IS_PRODUCTION) {
   dll = {
     manifestPath: path.join(dllCachePath, 'vendor.dll.manifest.json'),
     cacheFrom: dllCachePath,
-    cacheTo: path.join(ROOT_PATH, `public/assets/webpack/dll.${dllHash}/`),
+    cacheTo: path.join(WEBPACK_OUTPUT_PATH, `dll.${dllHash}/`),
     publicPath: `dll.${dllHash}/vendor.dll.bundle.js`,
     exists: null,
   };
@@ -157,8 +166,8 @@ module.exports = {
   entry: generateEntries,
 
   output: {
-    path: path.join(ROOT_PATH, 'public/assets/webpack'),
-    publicPath: '/assets/webpack/',
+    path: WEBPACK_OUTPUT_PATH,
+    publicPath: WEBPACK_PUBLIC_PATH,
     filename: IS_PRODUCTION ? '[name].[contenthash:8].bundle.js' : '[name].bundle.js',
     chunkFilename: IS_PRODUCTION ? '[name].[contenthash:8].chunk.js' : '[name].chunk.js',
     globalObject: 'this', // allow HMR and web workers to play nice
@@ -449,11 +458,11 @@ module.exports = {
     new CopyWebpackPlugin([
       {
         from: path.join(ROOT_PATH, 'node_modules/pdfjs-dist/cmaps/'),
-        to: path.join(ROOT_PATH, 'public/assets/webpack/cmaps/'),
+        to: path.join(WEBPACK_OUTPUT_PATH, 'cmaps/'),
       },
       {
-        from: path.join(ROOT_PATH, 'node_modules/@sourcegraph/code-host-integration/'),
-        to: path.join(ROOT_PATH, 'public/assets/webpack/sourcegraph/'),
+        from: path.join(ROOT_PATH, 'node_modules', SOURCEGRAPH_PACKAGE, '/'),
+        to: SOURCEGRAPH_OUTPUT_PATH,
         ignore: ['package.json'],
       },
       {
@@ -461,7 +470,7 @@ module.exports = {
           ROOT_PATH,
           'node_modules/@gitlab/visual-review-tools/dist/visual_review_toolbar.js',
         ),
-        to: path.join(ROOT_PATH, 'public/assets/webpack'),
+        to: WEBPACK_OUTPUT_PATH,
       },
     ]),
 
@@ -555,6 +564,8 @@ module.exports = {
       'process.env.IS_EE': JSON.stringify(IS_EE),
       // This one is used to check against "EE" properly in application code
       IS_EE: IS_EE ? 'window.gon && window.gon.ee' : JSON.stringify(false),
+      // This is used by Sourcegraph because these assets are loaded dnamically
+      'process.env.SOURCEGRAPH_PUBLIC_PATH': JSON.stringify(SOURCEGRAPH_PUBLIC_PATH),
     }),
 
     /* Pikaday has a optional dependency to moment.