feat: add using-cached flag to bench build

- add using-cache flag to node esbuild call

The flag is to be used by bench get-app if its is
using cache.

Flag causes building of assets to not run and
instead updates assets.json files from built assets.

Linking of assets in the sites folder also occurs.

esbuild/esbuild.js

@@ -64,6 +64,11 @@ const argv = yargs
 		description:
 			"Saves esbuild metafiles for built assets. Useful for analyzing bundle size. More info: https://esbuild.github.io/api/#metafile",
 	})
+	.option("using-cached", {
+		type: "boolean",
+		description:
+			"Skips build and uses cached build artifacts to update assets.json (used by Bench)",
+	})
 	.example("node esbuild --apps frappe,erpnext", "Run build only for frappe and erpnext")
 	.example(
 		"node esbuild --files frappe/website.bundle.js,frappe/desk.bundle.js",
@@ -88,6 +93,7 @@ const NODE_PATHS = [].concat(
 	// import js file of any app if you provide the full path
 	app_list.map((app) => path.resolve(get_app_path(app), "..")).filter(fs.existsSync)
 );
+const USING_CACHED = Boolean(argv["using-cached"]);
 
 execute().catch((e) => {
 	console.error(e);
@@ -101,6 +107,12 @@ if (WATCH_MODE) {
 
 async function execute() {
 	console.time(TOTAL_BUILD_TIME);
+	if (USING_CACHED) {
+		await update_assets_json_from_built_assets(APPS);
+		await update_assets_json_in_cache();
+		console.timeEnd(TOTAL_BUILD_TIME);
+		process.exit(0);
+	}
 
 	let results;
 	try {
@@ -131,6 +143,44 @@ async function execute() {
 	}
 }
 
+async function update_assets_json_from_built_assets(apps) {
+	const assets = await get_assets_json_path_and_obj(false);
+	const assets_rtl = await get_assets_json_path_and_obj(true);
+
+	for (const app in apps) {
+		await update_assets_obj(app, assets.obj, assets_rtl.obj);
+	}
+
+	for (const { obj, path } of [assets, assets_rtl]) {
+		const data = JSON.stringify(obj, null, 4);
+		await fs.promises.writeFile(path, data);
+	}
+}
+
+async function update_assets_obj(app, assets, assets_rtl) {
+	const app_path = get_app_path(app);
+	const dist_path = path.join(app_path, "public, dist");
+	const files = await glob("**/*.bundle.*.{js,css}", { cwd: dist_path });
+	const prefix = path.join("/", "assets", app, "dist");
+
+	// eg: "js/marketplace.bundle.6SCSPSGQ.js"
+	for (const file of files) {
+		// eg: [ "marketplace", "bundle", "6SCSPSGQ", "js" ]
+		const parts = path.parse(file).base.split(".");
+
+		// eg: "marketplace.bundle.js"
+		const key = [...parts.slice(0, -2), parts.at(-1)].join(".");
+
+		// eg: "js/marketplace.bundle.6SCSPSGQ.js"
+		const value = path.join(prefix, file);
+		if (file.includes("-rtl")) {
+			assets_rtl[`rtl_${key}`] = value;
+		} else {
+			assets[key] = value;
+		}
+	}
+}
+
 function build_assets_for_apps(apps, files) {
 	let { include_patterns, ignore_patterns } = files.length
 		? get_files_to_build(files)
@@ -393,14 +443,7 @@ async function write_assets_json(metafile) {
 		}
 	}
 
-	let assets_json_path = path.resolve(assets_path, `assets${rtl ? "-rtl" : ""}.json`);
-	let assets_json;
-	try {
-		assets_json = await fs.promises.readFile(assets_json_path, "utf-8");
-	} catch (error) {
-		assets_json = "{}";
-	}
-	assets_json = JSON.parse(assets_json);
+	let { obj: assets_json, path: assets_json_path } = await get_assets_json_path_and_obj(rtl);
 	// update with new values
 	let new_assets_json = Object.assign({}, assets_json, out);
 	curr_assets_json = new_assets_json;
@@ -434,6 +477,19 @@ async function update_assets_json_in_cache() {
 	});
 }
 
+async function get_assets_json_path_and_obj(is_rtl) {
+	const file_name = is_rtl ? "assets-rtl.json" : "assets.json";
+	const assets_json_path = path.resolve(assets_path, file_name);
+	let assets_json;
+	try {
+		assets_json = await fs.promises.readFile(assets_json_path, "utf-8");
+	} catch (error) {
+		assets_json = "{}";
+	}
+	assets_json = JSON.parse(assets_json);
+	return { obj: assets_json, path: assets_json_path };
+}
+
 function run_build_command_for_apps(apps) {
 	let cwd = process.cwd();
 	let { execSync } = require("child_process");

frappe/build.py

@@ -229,6 +229,7 @@ def bundle(
 	skip_frappe=False,
 	files=None,
 	save_metafiles=False,
+	using_cached=False,
 ):
 	"""concat / minify js files"""
 	setup()
@@ -246,7 +247,10 @@ def bundle(
 	if files:
 		command += " --files {files}".format(files=",".join(files))
 
-	command += " --run-build-command"
+	if using_cached:
+		command += " --using-cached"
+	else:
+		command += " --run-build-command"
 
 	if save_metafiles:
 		command += " --save-metafiles"

frappe/commands/utils.py

@@ -36,6 +36,12 @@ EXTRA_ARGS_CTX = {"ignore_unknown_options": True, "allow_extra_args": True}
 	default=False,
 	help="Saves esbuild metafiles for built assets. Useful for analyzing bundle size. More info: https://esbuild.github.io/api/#metafile",
 )
+@click.option(
+	"--using-cached",
+	is_flag=True,
+	default=False,
+	help="Skips build and uses cached build artifacts (cache is set by Bench). Ignored if developer_mode enabled.",
+)
 def build(
 	app=None,
 	apps=None,
@@ -44,6 +50,7 @@ def build(
 	verbose=False,
 	force=False,
 	save_metafiles=False,
+	using_cached=False,
 ):
 	"Compile JS and CSS source files"
 	from frappe.build import bundle, download_frappe_assets
@@ -69,6 +76,9 @@ def build(
 		if production:
 			mode = "production"
 
+		if development:
+			using_cached = False
+
 		bundle(
 			mode,
 			apps=apps,
@@ -76,6 +86,7 @@ def build(
 			verbose=verbose,
 			skip_frappe=skip_frappe,
 			save_metafiles=save_metafiles,
+			using_cached=using_cached,
 		)
 
 		if apps and isinstance(apps, str):