[Vite 3] /__vite_ping not always intercepted

[brillout]

Describe the bug

It seems like the first /__vite_ping slips through and isn't intercepted by Vite's dev middleware.

HMR still works, so it's not critical.

The vite-plugin-ssr middleware has a workaround, but for other middlewares, it can turn out to be an inconvenience to be hit by the /__vite_ping HTTP request and may lead to the pesky need for a workaround like vite-plugin-ssr's one.

Reproduction

https://github.com/brillout/vite3-ping-bug

EDIT: this reproduction doesn't actually work, see discussion below.

System Info

System:
    OS: Linux 5.10 Debian GNU/Linux 10 (buster) 10 (buster)
    CPU: (2) x64 Intel(R) Celeron(R) N4020 CPU @ 1.10GHz
    Memory: 253.08 MB / 2.71 GB
    Container: Yes
    Shell: 5.0.3 - /bin/bash
  Binaries:
    Node: 18.0.0 - ~/.config/nvm/versions/node/v18.0.0/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 8.6.0 - ~/.config/nvm/versions/node/v18.0.0/bin/npm
  Browsers:
    Firefox: 97.0.1
  npmPackages:
    @vitejs/plugin-react: ^1.3.2 => 1.3.2 
    vite: 3.0.0-beta.10 => 3.0.0-beta.10

Used Package Manager

pnpm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

I was not able to reproduce. Where is the /__vite_ping coming from? Is there anything I should to reproduce other than pnpm i and pnpm dev?

#6819 removed /__vite_ping ping to the server and now Vite pings to ws server instead (without /__vite_png). Then #8133 removed the code which handles /__vite_ping.
So I think it won't happen. 🤔
Maybe there is a Vite v2 client running?

[brillout]

Indeed, I closed all localhost tabs and I now can't reproduce anymore.

Thinking maybe Vite 3 should still intercept /__vite_ping for precisely that situation when someone has a Vite 2 client still lurking around.

[patak-dev]

I think this is too niche to add extra complexity. I imagine users will close the window and the problem is over.

[brillout]

Ok 👍. Closing then.

[khalwat]

My backend integration uses __vite_ping to detect if the Vite dev server is running, which is now broken in Vite 3: <nystudio107/craft-vite#37

What is the recommended way to check if the Vite dev server is running now? It'd be ideal of __vite_ping continued to work, so as to not have to special-case for specific Vite versions in my backend integration

[patak-dev]

We discussed with @khalwat, and seems he can do the same that was done in https://github.com/vitejs/vite/pull/6819/files, that should work in Vite 2 and Vite 3.