Patch the loadInstrumentationModule method to support Next.js 15 (#169)

Author: dario-piotrowicz

packages/cloudflare/src/cli/build/bundle-server.ts

@@ -16,6 +16,7 @@ import { inlineMiddlewareManifestRequire } from "./patches/to-investigate/inline
 import { inlineNextRequire } from "./patches/to-investigate/inline-next-require";
 import { patchExceptionBubbling } from "./patches/to-investigate/patch-exception-bubbling";
 import { patchFindDir } from "./patches/to-investigate/patch-find-dir";
+import { patchLoadInstrumentationModule } from "./patches/to-investigate/patch-load-instrumentation-module";
 import { patchReadFile } from "./patches/to-investigate/patch-read-file";
 import { patchWranglerDeps } from "./patches/to-investigate/wrangler-deps";
 import { copyPrerenderedRoutes } from "./utils";
@@ -164,6 +165,7 @@ async function updateWorkerBundledCode(
   patchedCode = await patchCache(patchedCode, openNextOptions);
   patchedCode = inlineMiddlewareManifestRequire(patchedCode, config);
   patchedCode = patchExceptionBubbling(patchedCode);
+  patchedCode = patchLoadInstrumentationModule(patchedCode);
 
   patchedCode = patchedCode
     // workers do not support dynamic require nor require.resolve

packages/cloudflare/src/cli/build/patches/to-investigate/patch-load-instrumentation-module.ts

@@ -0,0 +1,39 @@
+import * as ts from "ts-morph";
+
+import { tsParseFile } from "../../utils";
+
+/**
+ * The `loadInstrumentationModule` method (source: https://github.com/vercel/next.js/blob/5b7833e3/packages/next/src/server/next-server.ts#L301)
+ * calls `module.findSourceMap` (https://nodejs.org/api/module.html#modulefindsourcemappath) which we haven't implemented causing a runtime error.
+ *
+ * To solve this issue this function gets all the `loadInstrumentationModule` declarations found in the file and removes all the statements
+ * from their bodies (making them no-op methods).
+ *
+ * Instrumentation is a Next.js feature for monitoring and logging (see: https://nextjs.org/docs/app/building-your-application/optimizing/instrumentation),
+ * the removal of this method's logic most likely breaks this feature (see: https://nextjs.org/docs/app/api-reference/file-conventions/instrumentation),
+ * so this function is likely temporary and something that we'll have to fix in the future.
+ *
+ * TODO: investigate and re-enable instrumentation (https://github.com/opennextjs/opennextjs-cloudflare/issues/171)
+ */
+export function patchLoadInstrumentationModule(code: string) {
+  const file = tsParseFile(code);
+  const loadInstrumentationModuleDeclarations = file
+    .getDescendantsOfKind(ts.SyntaxKind.MethodDeclaration)
+    .filter((methodDeclaration) => {
+      if (methodDeclaration.getName() !== "loadInstrumentationModule") {
+        return false;
+      }
+      const methodModifierKinds = methodDeclaration.getModifiers().map((modifier) => modifier.getKind());
+      if (methodModifierKinds.length !== 1 || methodModifierKinds[0] !== ts.SyntaxKind.AsyncKeyword) {
+        return false;
+      }
+
+      return true;
+    });
+
+  loadInstrumentationModuleDeclarations.forEach((loadInstrumentationModuleDeclaration) => {
+    loadInstrumentationModuleDeclaration.setBodyText("");
+  });
+
+  return file.print();
+}