implement module finding in normal bundling if the find_additional_modules flag is on

Author: petebacondarwin

.changeset/clever-turkeys-leave.md

@@ -0,0 +1,20 @@
+---
+"wrangler": minor
+---
+
+feat: support partial bundling with configurable external modules
+
+Setting `find_additional_modules` to `true` in your configuration file will now instruct Wrangler to look for files in
+your `base_dir` that match your configured `rules`, and deploy them as unbundled, external modules with your Worker.
+`base_dir` defaults to the directory containing your `main` entrypoint.
+
+Wrangler can operate in two modes: the default bundling mode and `--no-bundle` mode. In bundling mode, dynamic imports
+(e.g. `await import("./large-dep.mjs")`) would be bundled into your entrypoint, making lazy loading less effective.
+Additionally, variable dynamic imports (e.g. `` await import(`./lang/${language}.mjs`) ``) would always fail at runtime,
+as Wrangler would have no way of knowing which modules to upload. The `--no-bundle` mode sought to address these issues
+by disabling Wrangler's bundling entirely, and just deploying code as is. Unfortunately, this also disabled Wrangler's
+code transformations (e.g. TypeScript compilation, `--assets`, `--test-scheduled`, etc).
+
+With this change, we now additionally support _partial bundling_. Files are bundled unless `find_additional_modules` is
+`true`, and the file matches one of the configured `rules`. See
+https://developers.cloudflare.com/workers/wrangler/bundling/ for more details and examples.

.prettierignore

@@ -7,6 +7,9 @@ packages/wrangler/CHANGELOG.md
 packages/jest-environment-wrangler/CHANGELOG.md
 packages/wranglerjs-compat-webpack-plugin/lib
 packages/wrangler-devtools/built-devtools
+packages/wrangler-devtools/.cipd
+packages/wrangler-devtools/depot
+packages/wrangler-devtools/devtools-frontend
 packages/edge-preview-authenticated-proxy/package.json
 packages/format-errors/package.json
 packages/**/dist/**

fixtures/additional-modules/package.json

@@ -0,0 +1,19 @@
+{
+	"name": "additional-modules",
+	"version": "0.0.1",
+	"private": true,
+	"scripts": {
+		"build": "wrangler deploy --dry-run --outdir=dist",
+		"check:type": "tsc",
+		"deploy": "wrangler deploy",
+		"start": "wrangler dev",
+		"test": "vitest run",
+		"test:ci": "vitest run",
+		"test:watch": "vitest",
+		"type:tests": "tsc -p ./test/tsconfig.json"
+	},
+	"devDependencies": {
+		"@cloudflare/workers-types": "^4.20230724.0",
+		"wrangler": "*"
+	}
+}

fixtures/additional-modules/src/dep.ts

@@ -0,0 +1 @@
+export default "bundled";

fixtures/additional-modules/src/dynamic.js

@@ -0,0 +1 @@
+export default "dynamic";

fixtures/additional-modules/src/index.ts

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+import dep from "./dep";
+import text from "./text.txt";
+
+export default <ExportedHandler>{
+	async fetch(request) {
+		const url = new URL(request.url);
+		if (url.pathname === "/dep") {
+			return new Response(dep);
+		}
+		if (url.pathname === "/text") {
+			return new Response(text);
+		}
+		if (url.pathname === "/dynamic") {
+			return new Response((await import("./dynamic.js")).default);
+		}
+		if (url.pathname.startsWith("/lang/")) {
+			const language = url.pathname.substring("/lang/".length);
+			return new Response(
+				(await import(`./lang/${language}.js`)).default.hello
+			);
+		}
+		return new Response("Not Found", { status: 404 });
+	},
+};

fixtures/additional-modules/src/lang/en.js

@@ -0,0 +1 @@
+export default { hello: "hello" };

fixtures/additional-modules/src/lang/fr.js

@@ -0,0 +1 @@
+export default { hello: "bonjour" };

fixtures/additional-modules/src/text.d.ts

@@ -0,0 +1,4 @@
+declare module "*.txt" {
+	const value: string;
+	export default value;
+}

fixtures/additional-modules/src/text.txt

@@ -0,0 +1 @@
+test