Use http instead of undici when waiting for runtime

...and disable keep-alives. This was a debugging step, but is
probably a good thing to do anyway. We're making lots of repeated
requests here, `http` is probably more optimised than `undici` atm.
In most cases, the socket will be closed as `workerd` won't be
listening yet, so keep-alives don't make sense.

Author: mrbbot

packages/tre/src/index.ts

@@ -620,7 +620,10 @@ export class Miniflare {
       exitController.signal,
       this.#disposeController.signal
     );
-    await waitForRequest(this.#runtimeEntryURL!, {
+    const url = this.#runtimeEntryURL!;
+    await waitForRequest({
+      hostname: url.hostname,
+      port: url.port,
       headers: { [HEADER_PROBE]: this.#optionsVersion.toString() },
       signal,
     });

packages/tre/src/wait.ts

@@ -1,6 +1,6 @@
+import http from "http";
 import type { TimerOptions } from "timers";
 import { setTimeout } from "timers/promises";
-import { request } from "undici";
 
 function attemptDelay(attempts: number) {
   if (attempts < 10) return 10;
@@ -9,28 +9,40 @@ function attemptDelay(attempts: number) {
   return 1000;
 }
 
-export async function waitForRequest(...options: Parameters<typeof request>) {
+// Disable keep-alive for polling requests
+const agent = new http.Agent({ keepAlive: false, maxSockets: 1 });
+
+function request(options: http.RequestOptions) {
+  return new Promise<number>((resolve, reject) => {
+    const req = http.request(options, (res) => {
+      resolve(res.statusCode ?? 0);
+      res.destroy();
+    });
+    req.on("error", (err) => reject(err));
+    req.end();
+  });
+}
+
+export async function waitForRequest(options: http.RequestOptions) {
+  options = { ...options, agent };
+
   let attempts = 0;
-  const signal = options[1]?.signal as AbortSignal | undefined;
+  const signal = options.signal;
   const timeoutOptions: TimerOptions = { signal };
 
   while (!signal?.aborted) {
     try {
-      const res = await request(...options);
-      const code = res.statusCode;
+      const code = await request(options);
       if (code !== undefined && 200 <= code && code < 300) return;
     } catch (e: any) {
       const code = e.code;
-      if (code === "UND_ERR_ABORTED") return;
+      if (code === "ABORT_ERR") return;
       if (
         // Adapted from https://github.com/dwmkerr/wait-port/blob/0d58d29a6d6b8ea996de9c6829706bb3b0952ee8/lib/wait-port.js
         code !== "ECONNREFUSED" &&
         code !== "ECONNTIMEOUT" &&
         code !== "ECONNRESET" &&
-        code !== "ENOTFOUND" &&
-        // Docker published port, but not bound in container
-        code !== "ECONNRESET" &&
-        code !== "UND_ERR_SOCKET"
+        code !== "ENOTFOUND"
       ) {
         throw e;
       }