make sure instrumentation works with Next 14

Author: dario-piotrowicz

examples/playground14/app/api/instrumentation/route.ts

@@ -1,5 +1,7 @@
 import { NextResponse } from "next/server";
 
+export const dynamic = "force-dynamic";
+
 export function GET() {
   return NextResponse.json({
     "nodejs-instrumentation-setup": globalThis["__NODEJS_INSTRUMENTATION_SETUP"] ?? "undefined",

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

@@ -17,6 +17,7 @@ import { inlineFindDir } from "./patches/plugins/find-dir.js";
 import { patchLoadInstrumentation } from "./patches/plugins/load-instrumentation.js";
 import { inlineLoadManifest } from "./patches/plugins/load-manifest.js";
 import { handleOptionalDependencies } from "./patches/plugins/optional-deps.js";
+import { patchPrepareImpl } from "./patches/plugins/prepare-impl.js";
 import { fixRequire } from "./patches/plugins/require.js";
 import { shimRequireHook } from "./patches/plugins/require-hook.js";
 import { inlineRequirePage } from "./patches/plugins/require-page.js";
@@ -92,6 +93,7 @@ export async function bundleServer(buildOpts: BuildOptions): Promise<void> {
       fixRequire(updater),
       handleOptionalDependencies(optionalDependencies),
       patchLoadInstrumentation(updater, buildOpts),
+      patchPrepareImpl(updater, buildOpts),
       patchFetchCacheSetMissingWaitUntil(updater),
       inlineEvalManifest(updater, buildOpts),
       inlineFindDir(updater, buildOpts),

packages/cloudflare/src/cli/build/patches/plugins/prepare-impl.spec.ts

@@ -0,0 +1,61 @@
+import { describe, expect, test, vi } from "vitest";
+
+import { patchCode } from "../ast/util.js";
+import { getRule } from "./prepare-impl.js";
+
+vi.mock(import("node:fs"), async (importOriginal) => {
+  const mod = await importOriginal();
+  return {
+    ...mod,
+    existsSync(path) {
+      return `${path}`.includes("_file_exists_");
+    },
+  };
+});
+
+describe("prepareImpl", () => {
+  const code = `
+      export default class NextNodeServer extends BaseServer {
+          async prepareImpl() {
+            await super.prepareImpl();
+            if (!this.serverOptions.dev && this.nextConfig.experimental.instrumentationHook) {
+              try {
+                const instrumentationHook = await dynamicRequire((0, _path.resolve)(this.serverOptions.dir || ".", this.serverOptions.conf.distDir, "server", _constants1.INSTRUMENTATION_HOOK_FILENAME));
+                await (instrumentationHook.register == null ? void 0 : instrumentationHook.register.call(instrumentationHook));
+              } catch (err2) {
+                if (err2.code !== "MODULE_NOT_FOUND") {
+                  err2.message = \`An error occurred while loading instrumentation hook: \${err2.message}\`;
+                  throw err2;
+                }
+              }
+            }
+          }
+      }
+    `;
+
+  test("patch when an instrumentation file is not present", async () => {
+    expect(patchCode(code, await getRule(null))).toMatchInlineSnapshot(`
+      "export default class NextNodeServer extends BaseServer {
+                async prepareImpl() {
+        await super.prepareImpl();
+        const instrumentationHook = null;
+        await (instrumentationHook.register == null ? void 0 : instrumentationHook.register.call(instrumentationHook));
+      }
+            }
+          "
+    `);
+  });
+
+  test("patch when an instrumentation file is present", async () => {
+    expect(patchCode(code, await getRule("/_file_exists_/instrumentation.js"))).toMatchInlineSnapshot(`
+      "export default class NextNodeServer extends BaseServer {
+                async prepareImpl() {
+        await super.prepareImpl();
+        const instrumentationHook = require('/_file_exists_/instrumentation.js');
+        await (instrumentationHook.register == null ? void 0 : instrumentationHook.register.call(instrumentationHook));
+      }
+            }
+          "
+    `);
+  });
+});

packages/cloudflare/src/cli/build/patches/plugins/prepare-impl.ts

@@ -0,0 +1,54 @@
+/**
+ * `prepareImpl` uses a dynamic require which is not supported.
+ *
+ * `prepareImpl` is the method that sets up instrumentation in Next 14 (this is `loadInstrumentationModule` in Next 15).
+ */
+
+import { existsSync } from "node:fs";
+import { join } from "node:path";
+
+import { type BuildOptions, getPackagePath } from "@opennextjs/aws/build/helper.js";
+
+import { patchCode } from "../ast/util.js";
+import type { ContentUpdater } from "./content-updater.js";
+
+export function patchPrepareImpl(updater: ContentUpdater, buildOpts: BuildOptions) {
+  const { outputDir } = buildOpts;
+
+  const baseDir = join(outputDir, "server-functions/default", getPackagePath(buildOpts));
+  const dotNextDir = join(baseDir, ".next");
+  const maybeBuiltInstrumentationPath = join(dotNextDir, "server", `${INSTRUMENTATION_HOOK_FILENAME}.js`);
+  const builtInstrumentationPath = existsSync(maybeBuiltInstrumentationPath)
+    ? maybeBuiltInstrumentationPath
+    : null;
+
+  return updater.updateContent(
+    "patch-prepareImpl",
+    { filter: /\.(js|mjs|cjs|jsx|ts|tsx)$/, contentFilter: /async prepareImpl\(/ },
+    async ({ contents }) => patchCode(contents, await getRule(builtInstrumentationPath))
+  );
+}
+
+export async function getRule(builtInstrumentationPath: string | null) {
+  return `
+    rule:
+      kind: method_definition
+      any:
+        - has: { field: name, regex: ^prepareImpl$, pattern: $NAME }
+      all:
+        - has: { pattern: dynamicRequire, stopBy: end }
+        - has: { pattern: $_.INSTRUMENTATION_HOOK_FILENAME, stopBy: end }
+    fix: |-
+        async $NAME() {
+          await super.prepareImpl();
+          const instrumentationHook = ${builtInstrumentationPath ? `require('${builtInstrumentationPath}')` : "null"};
+          await (instrumentationHook.register == null ? void 0 : instrumentationHook.register.call(instrumentationHook));
+        }
+  `;
+}
+
+/**
+ * Pattern to detect instrumentation hooks file
+ * (taken from Next.js source: https://github.com/vercel/next.js/blob/1d5820563/packages/next/src/lib/constants.ts#L46-L47)
+ */
+const INSTRUMENTATION_HOOK_FILENAME = "instrumentation";