refactor(wrangler): add metafile flag, pass to build functions, adjus… (#8716)

* refactor(wrangler): generate bundle meta file

* fixup! add test

* refactor(wrangler): add metafile flag, pass to build functions, adjust tests

---------

Co-authored-by: Victor Berchet <[email protected]>
Co-authored-by: emily-shen <[email protected]>

Author: 3 people

.changeset/soft-bears-pump.md

@@ -0,0 +1,5 @@
+---
+"wrangler": minor
+---
+
+add --metafile flag to generate esbuild metadata file during build

packages/wrangler/src/__tests__/deploy.test.ts

@@ -12646,6 +12646,34 @@ export default{
 		});
 	});
 
+	describe("--metafile", () => {
+		it("should output a metafile when --metafile is set", async () => {
+			writeWranglerConfig();
+			writeWorkerSource();
+			await runWrangler("deploy index.js --metafile --dry-run --outdir=dist");
+
+			// Check if file exists
+			const metafilePath = path.join(process.cwd(), "dist", "bundle-meta.json");
+			expect(fs.existsSync(metafilePath)).toBe(true);
+			const metafile = JSON.parse(fs.readFileSync(metafilePath, "utf8"));
+			expect(metafile.inputs).toBeDefined();
+			expect(metafile.outputs).toBeDefined();
+		});
+
+		it("should output a metafile when --metafile=./meta.json is set", async () => {
+			writeWranglerConfig();
+			writeWorkerSource();
+			await runWrangler("deploy index.js --metafile=./meta.json --dry-run");
+
+			// Check if file exists
+			const metafilePath = path.join(process.cwd(), "meta.json");
+			expect(fs.existsSync(metafilePath)).toBe(true);
+			const metafile = JSON.parse(fs.readFileSync(metafilePath, "utf8"));
+			expect(metafile.inputs).toBeDefined();
+			expect(metafile.outputs).toBeDefined();
+		});
+	});
+
 	describe("--dispatch-namespace", () => {
 		it("should upload to dispatch namespace", async () => {
 			writeWranglerConfig();

packages/wrangler/src/__tests__/pages/functions-build.test.ts

@@ -168,6 +168,29 @@ describe("pages functions build", () => {
 	`);
 	});
 
+	it("should output a metafile when --metafile is set", async () => {
+		// Setup a basic pages function
+		mkdirSync("functions");
+		writeFileSync(
+			"functions/hello.js",
+			`export function onRequest() { return new Response("Hello from Pages Functions"); }`
+		);
+
+		// Run the build command
+		await runWrangler(`pages functions build --outdir=dist --metafile`);
+
+		// Check if file exists
+		expect(existsSync("dist/bundle-meta.json")).toBe(true);
+
+		// Structure checks for the metafile
+		const meta = JSON.parse(
+			readFileSync("dist/bundle-meta.json", { encoding: "utf8" })
+		);
+
+		expect(meta.inputs).toBeDefined();
+		expect(meta.outputs).toBeDefined();
+	});
+
 	it("should build _worker.js", async () => {
 		/* ---------------------------- */
 		/*       Set up js files        */

packages/wrangler/src/api/startDevWorker/BundlerController.ts

@@ -149,6 +149,8 @@ export class BundlerController extends Controller<BundlerControllerEventMap> {
 
 						// sourcemap defaults to true in dev
 						sourcemap: undefined,
+
+						metafile: undefined,
 					});
 			if (buildAborter.signal.aborted) {
 				return;

packages/wrangler/src/deploy/deploy.ts

@@ -111,6 +111,7 @@ type Props = {
 	projectRoot: string | undefined;
 	dispatchNamespace: string | undefined;
 	experimentalAutoCreate: boolean;
+	metafile: string | boolean | undefined;
 };
 
 export type RouteObject = ZoneIdRoute | ZoneNameRoute | CustomDomainRoute;
@@ -550,6 +551,7 @@ See https://developers.cloudflare.com/workers/platform/compatibility-dates for m
 					props.entry,
 					typeof destination === "string" ? destination : destination.path,
 					{
+						metafile: props.metafile,
 						bundle: true,
 						additionalModules: [],
 						moduleCollector,

packages/wrangler/src/deploy/index.ts

@@ -168,6 +168,12 @@ export const deployCommand = createCommand({
 			describe: "Don't actually deploy",
 			type: "boolean",
 		},
+		metafile: {
+			describe:
+				"Path to output build metadata from esbuild. If flag is used without a path, defaults to 'bundle-meta.json' inside the directory specified by --outdir.",
+			type: "string",
+			coerce: (v: string) => (!v ? true : v),
+		},
 		"keep-vars": {
 			describe:
 				"Stop Wrangler from deleting vars that are not present in the Wrangler configuration file\nBy default Wrangler will remove all vars and replace them with those found in the Wrangler configuration.\nIf your development approach is to modify vars after deployment via the dashboard you may wish to set this flag.",
@@ -310,6 +316,7 @@ export const deployCommand = createCommand({
 			outDir: args.outdir,
 			outFile: args.outfile,
 			dryRun: args.dryRun,
+			metafile: args.metafile,
 			noBundle: !(args.bundle ?? !config.no_bundle),
 			keepVars: args.keepVars,
 			logpush: args.logpush,

packages/wrangler/src/deployment-bundle/bundle.ts

@@ -135,6 +135,7 @@ export type BundleOptions = {
 	projectRoot: string | undefined;
 	defineNavigatorUserAgent: boolean;
 	external: string[] | undefined;
+	metafile: string | boolean | undefined;
 };
 
 /**
@@ -170,6 +171,7 @@ export async function bundleWorker(
 		projectRoot,
 		defineNavigatorUserAgent,
 		external,
+		metafile,
 	}: BundleOptions
 ): Promise<BundleResult> {
 	// We create a temporary directory for any one-off files we
@@ -354,16 +356,18 @@ export async function bundleWorker(
 		entryPoints: [entry.file],
 		bundle,
 		absWorkingDir: entry.projectRoot,
-		outdir: destination,
 		keepNames,
-		entryNames: entryName || path.parse(entryFile).name,
 		...(isOutfile
 			? {
 					outdir: undefined,
 					outfile: destination,
 					entryNames: undefined,
 				}
-			: {}),
+			: {
+					outdir: destination,
+					outfile: undefined,
+					entryNames: entryName || path.parse(entryFile).name,
+				}),
 		inject,
 		external: bundle
 			? ["__STATIC_CONTENT_MANIFEST", ...(external ? external : [])]
@@ -438,6 +442,23 @@ export async function bundleWorker(
 			};
 		} else {
 			result = await esbuild.build(buildOptions);
+
+			// Write the bundle metafile to disk.
+			if (metafile && result.metafile) {
+				let metaFilePath: string;
+
+				if (typeof metafile === "string") {
+					metaFilePath = path.resolve(metafile);
+				} else if (isOutfile) {
+					metaFilePath = `${destination}.bundle-meta.json`;
+				} else {
+					metaFilePath = path.join(destination, "bundle-meta.json");
+				}
+
+				const metaJson = JSON.stringify(result.metafile, null, 2);
+				fs.writeFileSync(metaFilePath, metaJson);
+			}
+
 			// Even when we're not watching, we still want some way of cleaning up the
 			// temporary directory when we don't need it anymore
 			stop = async function () {

packages/wrangler/src/dev/use-esbuild.ts

@@ -172,6 +172,8 @@ export function runBuild(
 						// sourcemap defaults to true in dev
 						sourcemap: undefined,
 						checkFetch,
+
+						metafile: undefined,
 					})
 				: undefined;
 

packages/wrangler/src/pages/build.ts

@@ -136,6 +136,12 @@ export const pagesFunctionsBuildCommand = createCommand({
 			type: "string",
 			array: true,
 		},
+		metafile: {
+			describe:
+				"Path to output build metadata from esbuild. If flag is used without a path, defaults to 'bundle-meta.json' inside the directory specified by --outdir.",
+			type: "string",
+			coerce: (v: string) => (!v ? true : v),
+		},
 	},
 	positionalArgs: ["directory"],
 	async handler(args) {
@@ -159,6 +165,7 @@ export const pagesFunctionsBuildCommand = createCommand({
 				defineNavigatorUserAgent,
 				checkFetch,
 				external,
+				metafile,
 			} = validatedArgs;
 
 			try {
@@ -186,6 +193,7 @@ export const pagesFunctionsBuildCommand = createCommand({
 					defineNavigatorUserAgent,
 					checkFetch,
 					external,
+					metafile,
 				});
 			} catch (e) {
 				if (e instanceof FunctionsNoRoutesError) {
@@ -228,6 +236,7 @@ export const pagesFunctionsBuildCommand = createCommand({
 				defineNavigatorUserAgent,
 				checkFetch,
 				external,
+				metafile,
 			} = validatedArgs;
 
 			/**
@@ -289,6 +298,7 @@ export const pagesFunctionsBuildCommand = createCommand({
 						defineNavigatorUserAgent,
 						checkFetch,
 						external,
+						metafile,
 					});
 				} catch (e) {
 					if (e instanceof FunctionsNoRoutesError) {

packages/wrangler/src/pages/buildFunctions.ts

@@ -41,6 +41,7 @@ export async function buildFunctions({
 	defineNavigatorUserAgent,
 	checkFetch,
 	external,
+	metafile,
 }: Partial<
 	Pick<
 		typeof pagesFunctionsBuildCommand.args,
@@ -66,6 +67,7 @@ export async function buildFunctions({
 	routesModule?: string;
 	defineNavigatorUserAgent: boolean;
 	checkFetch: boolean;
+	metafile?: string | boolean;
 }) {
 	RUNNING_BUILDERS.forEach(
 		(runningBuilder) => runningBuilder.stop && runningBuilder.stop()
@@ -143,6 +145,7 @@ export async function buildFunctions({
 			defineNavigatorUserAgent,
 			checkFetch,
 			external,
+			metafile,
 		});
 	}