Allow __STATIC_CONTENT_MANIFEST to be imported from any directory

Previously, `import manifest from "__STATIC_CONTENT_MANIFEST"` was
only allowed in the "root" directory of the modules virtual
file-system. This change adds stub modules for each additional module
in each subdirectory, that re-export the module. This allows the
manifest to be imported in any directory.

Author: mrbbot

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

@@ -1,6 +1,7 @@
 import assert from "assert";
 import { readFileSync } from "fs";
 import fs from "fs/promises";
+import path from "path";
 import tls from "tls";
 import { TextEncoder } from "util";
 import { bold } from "kleur/colors";
@@ -374,10 +375,7 @@ export const CORE_PLUGIN: Plugin<
     sourceMapRegistry,
   }) {
     // Define regular user worker
-    const additionalModuleNames = additionalModules.map(({ name }) => {
-      assert(name !== undefined);
-      return name;
-    });
+    const additionalModuleNames = additionalModules.map(({ name }) => name);
     const workerScript = getWorkerScript(
       sourceMapRegistry,
       options,
@@ -386,7 +384,32 @@ export const CORE_PLUGIN: Plugin<
     );
     // Add additional modules (e.g. "__STATIC_CONTENT_MANIFEST") if any
     if ("modules" in workerScript) {
-      workerScript.modules.push(...additionalModules);
+      const subDirs = new Set(
+        workerScript.modules.map(({ name }) => path.posix.dirname(name))
+      );
+      // Ignore `.` as it's not a subdirectory, and we don't want to register
+      // additional modules in the root twice.
+      subDirs.delete(".");
+
+      for (const module of additionalModules) {
+        workerScript.modules.push(module);
+        // In addition to adding the module, we add stub modules in each
+        // subdirectory re-exporting each additional module. These allow
+        // additional modules to be imported in every directory.
+        for (const subDir of subDirs) {
+          const relativePath = path.posix.relative(subDir, module.name);
+          const relativePathString = JSON.stringify(relativePath);
+          workerScript.modules.push({
+            name: path.posix.join(subDir, module.name),
+            // TODO(someday): if we ever have additional modules without
+            //  default exports, this may be a problem. For now, our only
+            //  additional module is `__STATIC_CONTENT_MANIFEST` so it's fine.
+            //  If needed, we could look for instances of `export default` or
+            //  `as default` in the module's code as a heuristic.
+            esModule: `export * from ${relativePathString}; export { default } from ${relativePathString};`,
+          });
+        }
+      }
     }
 
     const name = getUserServiceName(options.name);

packages/miniflare/src/runtime/config/workerd.ts

@@ -67,7 +67,7 @@ export type Worker_DurableObjectStorage =
   | { localDisk?: string };
 
 export type Worker_Module = {
-  name?: string;
+  name: string;
 } & (
   | { esModule?: string }
   | { commonJsModule?: string }

packages/miniflare/test/plugins/kv/sites.spec.ts

@@ -169,6 +169,62 @@ test("gets assets with module worker", async (t) => {
   t.is(await res.text(), "nested");
 });
 
+test("can import manifest from any directory", async (t) => {
+  const tmp = await useTmp(t);
+  const testPath = path.join(tmp, "test.txt");
+  await fs.writeFile(testPath, "test", "utf8");
+  const mf = new Miniflare({
+    modules: [
+      {
+        type: "ESModule",
+        path: "index.mjs",
+        contents: `
+        import root from "__STATIC_CONTENT_MANIFEST";
+        import a1 from "./a/1.mjs";
+        import ab2 from "./a/b/2.mjs";
+        import ab3 from "./a/b/3.mjs";
+        import abc4 from "./a/b/c/4.mjs";
+        
+        export default {
+          async fetch() {
+            return Response.json({
+              a1: a1 === root,
+              ab2: ab2 === root,
+              ab3: ab3 === root,
+              abc4: abc4 === root,
+            });
+          }
+        }
+        `,
+      },
+      {
+        type: "ESModule",
+        path: "a/1.mjs",
+        contents: 'export { default } from "__STATIC_CONTENT_MANIFEST";',
+      },
+      {
+        type: "ESModule",
+        path: "a/b/2.mjs",
+        contents: 'export { default } from "__STATIC_CONTENT_MANIFEST";',
+      },
+      {
+        type: "ESModule",
+        path: "a/b/3.mjs",
+        contents: 'export { default } from "__STATIC_CONTENT_MANIFEST";',
+      },
+      {
+        type: "ESModule",
+        path: "a/b/c/4.mjs",
+        contents: 'export { default } from "__STATIC_CONTENT_MANIFEST";',
+      },
+    ],
+    sitePath: tmp,
+  });
+  t.teardown(() => mf.dispose());
+  const res = await mf.dispatchFetch("http://localhost:8787/test.txt");
+  t.deepEqual(await res.json(), { a1: true, ab2: true, ab3: true, abc4: true });
+});
+
 test("gets assets with percent-encoded paths", async (t) => {
   // https://github.com/cloudflare/miniflare/issues/326
   const tmp = await useTmp(t);