instead of patching the tracer.js file to throw on @opentelemetry/api imports, delete the @opentelemetry/api dependency itself

Author: dario-piotrowicz

Diff for: .changeset/forty-jobs-press.md

@@ -0,0 +1,9 @@
+---
+"@opennextjs/cloudflare": patch
+---
+
+instead of patching the `tracer.js` file to throw on `@opentelemetry/api` imports, delete the `@opentelemetry/api` dependency itself
+
+the problem that this addresses is that the `@opentelemetry/api` package is not only imported by the `tracer.js` file
+we patch, so just deleting the library itself makes sure that all files requiring it get the same throwing behavior
+(besides decreasing the overall worker size)

Diff for: packages/cloudflare/src/cli/build/open-next/createServerBundle.ts

@@ -17,6 +17,7 @@ import { openNextReplacementPlugin } from "@opennextjs/aws/plugins/replacement.j
 import { openNextResolvePlugin } from "@opennextjs/aws/plugins/resolve.js";
 import type { FunctionOptions, SplittedFunctionOptions } from "@opennextjs/aws/types/open-next.js";
 
+import { deleteOpenTelemetryDep } from "../patches/index.js";
 import { normalizePath } from "../utils/index.js";
 
 export async function createServerBundle(options: buildHelper.BuildOptions) {
@@ -86,12 +87,14 @@ export async function createServerBundle(options: buildHelper.BuildOptions) {
   }
 
   // Generate default function
-  await generateBundle("default", options, {
+  const outputPath = await generateBundle("default", options, {
     ...defaultFn,
     // @ts-expect-error - Those string are RouteTemplate
     routes: Array.from(remainingRoutes),
     patterns: ["*"],
   });
+
+  deleteOpenTelemetryDep(outputPath);
 }
 
 async function generateBundle(
@@ -250,6 +253,8 @@ CMD ["node", "index.mjs"]
     `
     );
   }
+
+  return outputPath;
 }
 
 function shouldGenerateDockerfile(options: FunctionOptions) {

Diff for: packages/cloudflare/src/cli/build/patches/investigated/delete-open-telemetry-dep.ts

@@ -0,0 +1,23 @@
+import { rmSync } from "node:fs";
+import { join } from "node:path";
+
+/**
+ * Given a directory path, it deletes a `node_modules/@opentelemetry` subdirectory if present.
+ *
+ * Explanation:
+ *  The standard `@opentelemetry/api` library doesn't work in workerd since there are paths that it can't resolve (without a
+ *  compilation step), fortunately Next.js has a try-catch statement that replaces, when failing, `require('@opentelemetry/api')`
+ *  calls with a precompiled version of the library ('next/dist/compiled/@opentelemetry/api') which does properly in our runtime
+ *  (source code: https://github.com/vercel/next.js/blob/9e8266a7/packages/next/src/server/lib/trace/tracer.ts#L27-L31)
+ *
+ *  So this function is used to delete the `@opentelemetry` dependency entirely so to guarantee that
+ *  `require('@opentelemetry/api')` fail ensuring that the precompiled version is used
+ */
+export async function deleteOpenTelemetryDep(path: string): Promise<void> {
+  const nodeModulesDirPath = join(path, "node_modules");
+
+  rmSync(join(nodeModulesDirPath, "@opentelemetry"), {
+    recursive: true,
+    force: true,
+  });
+}

Diff for: packages/cloudflare/src/cli/build/patches/investigated/index.ts

@@ -1,4 +1,5 @@
 export * from "./copy-package-cli-files.js";
+export * from "./delete-open-telemetry-dep.js";
 export * from "./patch-cache.js";
 export * from "./patch-require.js";
 export * from "./update-webpack-chunks-file/index.js";

Diff for: packages/cloudflare/src/cli/build/patches/to-investigate/wrangler-deps.ts

@@ -5,10 +5,13 @@ import * as ts from "ts-morph";
 
 import { Config } from "../../../config.js";
 import { tsParseFile } from "../../utils/index.js";
+import { deleteOpenTelemetryDep } from "../investigated/delete-open-telemetry-dep.js";
 
 export function patchWranglerDeps(config: Config) {
   console.log("# patchWranglerDeps");
 
+  deleteOpenTelemetryDep(config.paths.output.standaloneRoot);
+
   const distPath = getDistPath(config);
   // Patch .next/standalone/node_modules/next/dist/compiled/next-server/pages.runtime.prod.js
   //
@@ -27,25 +30,6 @@ export function patchWranglerDeps(config: Config) {
   writeFileSync(pagesRuntimeFile, patchedPagesRuntime);
 
   patchRequireReactDomServerEdge(config);
-
-  // Patch .next/standalone/node_modules/next/dist/server/lib/trace/tracer.js
-  //
-  // Remove the need for an alias in wrangler.toml:
-  //
-  // [alias]
-  // # @opentelemetry/api is `require`d when running wrangler dev, so we need to stub it out
-  // # IMPORTANT: we shim @opentelemetry/api to the throwing shim so that it will throw right away, this is so that we throw inside the
-  // #            try block here: https://github.com/vercel/next.js/blob/9e8266a7/packages/next/src/server/lib/trace/tracer.ts#L27-L31
-  // #            causing the code to require the 'next/dist/compiled/@opentelemetry/api' module instead (which properly works)
-  // #"@opentelemetry/api" = "./.next/standalone/node_modules/cf/templates/shims/throw.ts"
-  const tracerFile = join(distPath, "server", "lib", "trace", "tracer.js");
-
-  const patchedTracer = readFileSync(tracerFile, "utf-8").replaceAll(
-    /\w+\s*=\s*require\([^/]*opentelemetry.*\)/g,
-    `throw new Error("@opentelemetry/api")`
-  );
-
-  writeFileSync(tracerFile, patchedTracer);
 }
 
 /**