Keep Node.js ESM packages working when consumers rebundle them as CommonJS (#15870)

Author: dario-piotrowicz

.changeset/clever-dodos-require.md

@@ -0,0 +1,11 @@
+---
+"@cloudflare/autoconfig": patch
+"@cloudflare/codemods": patch
+"@cloudflare/deploy-helpers": patch
+"@cloudflare/workers-auth": patch
+"@cloudflare/workers-utils": patch
+---
+
+Keep Node.js ESM packages working when consumers rebundle them as CommonJS
+
+Node.js-targeted ESM bundles now provide a real `require` implementation for bundled CommonJS dependencies. This avoids downstream patches for dynamic require calls and keeps the packages usable when a consumer rebundles them to CommonJS.

packages/autoconfig/tsup.config.ts

@@ -7,6 +7,11 @@ export default defineConfig(() => [
 		keepNames: true,
 		entry: ["src/index.ts"],
 		platform: "node",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
+		banner: {
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
+		},
 		format: "esm",
 		dts: true,
 		outDir: "dist",

packages/codemods/tsup.config.ts

@@ -13,8 +13,10 @@ export default defineConfig(() => [
 		tsconfig: "tsconfig.json",
 		metafile: true,
 		sourcemap: process.env.SOURCEMAPS !== "false",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
 		banner: {
-			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url);',
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
 		},
 		noExternal: [/.*/],
 	},

packages/containers-shared/tsup.config.ts

@@ -13,7 +13,7 @@ export default defineConfig(() => [
 		// Bundled ws uses CommonJS imports for Node builtins. Miniflare bundles
 		// this package into CJS, where import.meta.url is unavailable.
 		banner: {
-			js: 'import { createRequire } from "node:module"; const require = createRequire(typeof __filename === "string" ? __filename : import.meta.url);',
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
 		},
 		format: "esm",
 		dts: true,

packages/deploy-helpers/tsup.config.ts

@@ -16,6 +16,11 @@ export default defineConfig(() => [
 			"startup-profile": "src/startup-profile.ts",
 		},
 		platform: "node",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
+		banner: {
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
+		},
 		format: "esm",
 		dts: true,
 		outDir: "dist",

packages/shared-ast-primitives/tsup.config.ts

@@ -6,6 +6,11 @@ export default defineConfig(() => [
 		keepNames: true,
 		entry: ["src/index.ts"],
 		platform: "node",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
+		banner: {
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
+		},
 		format: "esm",
 		dts: true,
 		outDir: "dist",

packages/workers-auth/tsup.config.ts

@@ -11,6 +11,11 @@ export default defineConfig(() => [
 			"src/test-helpers/index.ts",
 		],
 		platform: "node",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
+		banner: {
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
+		},
 		format: "esm",
 		dts: true,
 		outDir: "dist",

packages/workers-utils/tsup.config.ts

@@ -2,12 +2,28 @@ import { defineConfig } from "tsup";
 import { EXTERNAL_DEPENDENCIES } from "./scripts/deps";
 
 export default defineConfig(() => [
+	{
+		treeshake: true,
+		keepNames: true,
+		// Keep the browser export free of the Node-only banner used below.
+		entry: ["src/browser.ts"],
+		platform: "node",
+		format: "esm",
+		dts: true,
+		outDir: "dist",
+		tsconfig: "tsconfig.json",
+		metafile: true,
+		sourcemap: process.env.SOURCEMAPS !== "false",
+		define: {
+			"process.env.NODE_ENV": `'${"production"}'`,
+		},
+		external: ["@cloudflare/*", "vitest", ...EXTERNAL_DEPENDENCIES],
+	},
 	{
 		treeshake: true,
 		keepNames: true,
 		entry: [
 			"src/index.ts",
-			"src/browser.ts",
 			"src/prometheus-metrics.ts",
 			"src/test-helpers/index.ts",
 			// Leaf entry points let consumers bundle individual utilities without
@@ -22,6 +38,11 @@ export default defineConfig(() => [
 			"src/zod-format.ts",
 		],
 		platform: "node",
+		// Provide require for bundled CommonJS dependencies. The __filename
+		// fallback keeps the output working when it is rebundled to CommonJS.
+		banner: {
+			js: 'import { createRequire as __createRequire } from "node:module"; const require = __createRequire(import.meta.url || (typeof __filename === "string" ? __filename : "/"));',
+		},
 		format: "esm",
 		dts: true,
 		outDir: "dist",