chore(web): produce manifest file listing all compass-web assets as part of compilation COMPASS-10131 (#7624)

* chore(web): produce manifest file listing all compass-web assets as part of compilation

* fix(web): use emitAssets instead of direct fs call to account for webpack in-memory fs

Author: gribnoysup

packages/compass-web/webpack.config.js

@@ -163,6 +163,40 @@ module.exports = (env, args) => {
         process: [localPolyfill('process'), 'process'],
       }),
 
+      // Plugin to collect entrypoint filename information and save it in a
+      // manifest file
+      function (compiler) {
+        compiler.hooks.emit.tap('manifest', function (compilation) {
+          const stats = compilation.getStats().toJson({
+            all: false,
+            outputPath: true,
+            entrypoints: true,
+          });
+
+          if (!('index' in stats.entrypoints)) {
+            throw new Error('Missing expected entrypoint in the stats object');
+          }
+
+          const assets = JSON.stringify(
+            stats.entrypoints.index.assets
+              .map((asset) => {
+                return asset.name;
+              })
+              // The root entrypoint is at the end of the assets list, but
+              // we'd want to preload it first, reversing here puts the
+              // manifest list in the load order we want
+              .reverse(),
+            null,
+            2
+          );
+
+          compilation.emitAsset(
+            'assets-manifest.json',
+            new webpack.sources.RawSource(assets)
+          );
+        });
+      },
+
       // Only applied when running webpack in --watch mode. In this mode we want
       // to constantly rebuild d.ts files when source changes, we also don't
       // want to fail and stop compilation if we failed to generate definitions
@@ -251,7 +285,9 @@ module.exports = (env, args) => {
   config.output = {
     path: config.output.path,
     filename: (pathData) => {
-      return pathData.chunk.hasEntryModule() ? 'compass-web.mjs' : '[name].mjs';
+      return pathData.chunk.hasEntryModule()
+        ? 'compass-web.mjs'
+        : '[name].[contenthash].mjs';
     },
     library: {
       type: 'module',