Support compiling webpacker content from addons [SCI-7187]

config/webpack/environment.js

@@ -1,9 +1,39 @@
 const { environment } = require('@rails/webpacker')
 const { VueLoaderPlugin } = require('vue-loader')
 const vue = require('./loaders/vue')
+const { execSync } = require('child_process');
+const { basename, resolve } = require('path');
+const { readdirSync } = require('fs');
 
 environment.loaders.delete('nodeModules')
 environment.plugins.prepend('VueLoaderPlugin', new VueLoaderPlugin())
 environment.loaders.prepend('vue', vue)
 
-module.exports = environment
+// Engine pack loading based on https://github.com/rails/webpacker/issues/348#issuecomment-635480949
+// Get paths to all engines' folders
+const enginePaths = execSync('ls -d $PWD/addons/*').toString().split('\n').filter((p) => !!p);
+enginePaths.forEach((path) => {
+  const packsFolderPath = `${path}/app/javascript/packs`;
+
+  let entryFiles;
+  try {
+    entryFiles = readdirSync(packsFolderPath);
+    console.log(`Found packs in ${path}`);
+  } catch {
+    console.log(`No packs in ${path}`);
+    return;
+  }
+
+  entryFiles.forEach((file) => {
+    // File name without .js
+    const name = basename(file, '.js');
+    const entryPath = `${packsFolderPath}/${file}`;
+
+    environment.entry.set(name, entryPath);
+  });
+
+  // Otherwise babel won't transpile the file
+  environment.loaders.get('babel').include.push(`${path}/app/javascript`);
+});
+
+module.exports = environment;

engines_yarn_install.js

@@ -0,0 +1,11 @@
+#!/usr/bin/env node
+
+const { spawn, execSync } = require('child_process');
+const enginePaths = execSync('ls -d $PWD/addons/*').toString().split('\n').filter((p) => !!p);
+enginePaths.forEach(enginePath => {
+  spawn('yarn', ['install'], {
+    env: process.env,
+    cwd: enginePath,
+    stdio: 'inherit'
+  });
+});

package.json

@@ -20,6 +20,7 @@
     "flow": "flow",
     "lint": "eslint ."
   },
+  "postinstall": "./engines_yarn_install.js",
   "devDependencies": {
     "@babel/core": "^7.0.0",
     "@babel/plugin-transform-react-jsx-source": "^7.0.0",