fix: remove __STATIC_CONTENT_MANIFEST from module worker env (#4505)

Author: mrbbot

.changeset/soft-chairs-share.md

@@ -0,0 +1,7 @@
+---
+"miniflare": patch
+---
+
+fix: remove `__STATIC_CONTENT_MANIFEST` from module worker `env`
+
+When using Workers Sites with a module worker, the asset manifest must be imported from the `__STATIC_CONTENT_MANIFEST` virtual module. Miniflare provided this module, but also erroneously added `__STATIC_CONTENT_MANIFEST` to the `env` object too. Whilst this didn't break anything locally, it could cause users to develop Workers that ran locally, but not when deployed. This change ensures `env` doesn't contain `__STATIC_CONTENT_MANIFEST`.

packages/miniflare/src/index.ts

@@ -62,7 +62,6 @@ import {
 	getDirectSocketName,
 	getGlobalServices,
 	kProxyNodeBinding,
-	maybeGetSitesManifestModule,
 	normaliseDurableObject,
 } from "./plugins";
 import {
@@ -104,6 +103,7 @@ import {
 	LogLevel,
 	Mutex,
 	SharedHeaders,
+	SiteBindings,
 } from "./workers";
 import { _formatZodError } from "./zod-format";
 
@@ -996,6 +996,7 @@ export class Miniflare {
 		for (let i = 0; i < allWorkerOpts.length; i++) {
 			const workerOpts = allWorkerOpts[i];
 			const workerName = workerOpts.core.name ?? "";
+			const isModulesWorker = Boolean(workerOpts.core.modules);
 
 			// Collect all bindings from this worker
 			const workerBindings: Worker_Binding[] = [];
@@ -1007,7 +1008,23 @@ export class Miniflare {
 				const pluginBindings = await plugin.getBindings(workerOpts[key], i);
 				if (pluginBindings !== undefined) {
 					for (const binding of pluginBindings) {
-						workerBindings.push(binding);
+						// If this is the Workers Sites manifest, we need to add it as a
+						// module for modules workers. For all other bindings, and in
+						// service workers, just add to worker bindings.
+						if (
+							key === "kv" &&
+							binding.name === SiteBindings.JSON_SITE_MANIFEST &&
+							isModulesWorker
+						) {
+							assert("json" in binding && binding.json !== undefined);
+							additionalModules.push({
+								name: SiteBindings.JSON_SITE_MANIFEST,
+								text: binding.json,
+							});
+						} else {
+							workerBindings.push(binding);
+						}
+
 						// Only `workerd` native bindings need to be proxied, the rest are
 						// already supported by Node.js (e.g. json, text/data blob, wasm)
 						if (isNativeTargetBinding(binding)) {
@@ -1032,12 +1049,6 @@ export class Miniflare {
 							}
 						}
 					}
-
-					if (key === "kv") {
-						// Add "__STATIC_CONTENT_MANIFEST" module if sites enabled
-						const module = maybeGetSitesManifestModule(pluginBindings);
-						if (module !== undefined) additionalModules.push(module);
-					}
 				}
 			}
 

packages/miniflare/src/plugins/kv/index.ts

@@ -146,5 +146,4 @@ export const KV_PLUGIN: Plugin<
 	},
 };
 
-export { maybeGetSitesManifestModule } from "./sites";
 export { KV_PLUGIN_NAME };

packages/miniflare/src/plugins/kv/sites.ts

@@ -2,7 +2,7 @@ import assert from "assert";
 import fs from "fs/promises";
 import path from "path";
 import SCRIPT_KV_SITES from "worker:kv/sites";
-import { Service, Worker_Binding, Worker_Module } from "../../runtime";
+import { Service, Worker_Binding } from "../../runtime";
 import { globsToRegExps } from "../../shared";
 import {
 	SharedBindings,
@@ -102,17 +102,6 @@ export async function getSitesNodeBindings(
 	};
 }
 
-export function maybeGetSitesManifestModule(
-	bindings: Worker_Binding[]
-): Worker_Module | undefined {
-	for (const binding of bindings) {
-		if (binding.name === SiteBindings.JSON_SITE_MANIFEST) {
-			assert("json" in binding && binding.json !== undefined);
-			return { name: SiteBindings.JSON_SITE_MANIFEST, text: binding.json };
-		}
-	}
-}
-
 export function getSitesServices(options: SitesOptions): Service[] {
 	// `siteRegExps` should've been set in `getSitesBindings()`, and `options`
 	// should be the same object reference as before.

packages/miniflare/test/fixtures/sites/modules.ts

@@ -2,8 +2,22 @@ import { getAssetFromKV } from "@cloudflare/kv-asset-handler";
 import manifestJSON from "__STATIC_CONTENT_MANIFEST";
 const manifest = JSON.parse(manifestJSON);
 
-export default <ExportedHandler<{ __STATIC_CONTENT: KVNamespace }>>{
+export default <
+	ExportedHandler<{
+		__STATIC_CONTENT: KVNamespace;
+		__STATIC_CONTENT_MANIFEST?: undefined;
+	}>
+>{
 	async fetch(request, env, ctx) {
+		if (
+			"__STATIC_CONTENT_MANIFEST" in env ||
+			env.__STATIC_CONTENT_MANIFEST !== undefined
+		) {
+			return new Response(
+				"Expected __STATIC_CONTENT_MANIFEST to be undefined",
+				{ status: 500 }
+			);
+		}
 		return await getAssetFromKV(
 			{
 				request,