Astro runs on :3000 port even though another app is running on the same port

[yxshv]

What version of astro are you using?

1.0.1

Are you using an SSR adapter? If so, which one?

no

What package manager are you using?

pnpm

What operating system are you using?

Windows

Describe the Bug

I had a React app running on port 3000 and ran an astro app thinking that it will automatically use a different port. Bu, it didn't

Link to Minimal Reproducible Example

just run an different app on localhot:3000 and then run an astro app

Participation

• I am willing to submit a pull request for this issue.

[bluwy]

Astro's dev server uses Vite. Does this happen on a Vite app too? Also, is your React app running on http://172.0.0.1:3000 or http://[::1]:3000. The port detection depends on which hostname your React app is running vs Vite's

[FredKSchott]

I can't reproduce. When I have something running on :3000, astro dev starts on :3001 instead. Maybe this is a Windows limitation?

[FredKSchott]

@yxshv can you go into your node_modules folder and add some logging to this file? I'm curious if onError isn't being hit here on Windows.

astro/packages/astro/src/core/preview/index.ts

Lines 135 to 148 in 485742d

	const onError = (err: NodeJS.ErrnoException) => {
	if (err.code && err.code === 'EADDRINUSE') {
	if (!showedPortTakenMsg) {
	info(logging, 'astro', msg.portInUse({ port }));
	showedPortTakenMsg = true; // only print this once
	}
	port++;
	return listen(); // retry
	} else {
	error(logging, 'astro', err.stack || err.message);
	httpServer?.removeListener('error', onError);
	reject(err); // reject
	}
	};

[yxshv]

@FredKSchott Nope it does not.

        httpServer == null ? void 0 : httpServer.on("error", onError);
      };
      const onError = (err) => {
        console.log(err)    // +++++++++++
        if (err.code && err.code === "EADDRINUSE") {
          if (!showedPortTakenMsg) {
            console.log("port taken")    // +++++++++++
            info(logging, "astro", msg.portInUse({ port }));
            showedPortTakenMsg = true;
          }
          port++;
          return listen();

       listen();
    });
  }
  console.log("starting server");    // +++++++++
  await startServer(startServerTime);
  function closed() {
    return new Promise((resolve, reject) => {
      httpServer.addListener("close", resolve);
      httpServer.addListener("error", reject);
    });
  }

[yxshv]

I thought. Lets just use a different PORT and added PORT=3001 in environment variables

and to my surprise it still ran on :3000

[bluwy]

and to my surprise it still ran on :3000

I don't think we support reading from PORT.

Is this issue related to astro dev or astro preview or both? And how are you starting your other app

[yxshv]

and to my surprise it still ran on :3000

I don't think we support reading from PORT.

Is this issue related to astro dev or astro preview or both? And how are you starting your other app

oh. It does not work on both dev and preview

I am starting the other react (nextjs) app with pnpm dev

[SachaG]

Same issue here: