This would make an SSR plugin doable without making a wrapper CLI for Vite! Awesome feature! 🔥🚀

Instead of a new hook, I am thinking we could either:

{
  name: 'myplugin',
  configureServer(server, mode) {
    if (mode === 'preview') {
      //...
    }
  }
}

or

{
  name: 'myplugin',
  apply: 'preview', // normal plugins won't apply to preview unless set explictly
  configureServer(server) {
     //...
  }
}

Instead of a new hook

I share the sentiment and it was actually my initial implementation. But I'm not sure how we could make it work with TypeScript:

type PreviewServer = { middlewares: Connect.Server, httpServer: http.Server }
{
  name: 'myplugin',
  // Is `server` a `ViteDevServer` or a `PreviewServer`?
  configureServer(server) {
      //...
  }
}

Setting server to ViteDevServer | PreviewServer is not ideal for DX. I'd argue that TypeScript DX justifies the creation of a new hook.

This would make an SSR plugin doable without making a wrapper CLI for Vite! Awesome feature! 🔥🚀

Exactly. This is actually what is happening with vps: https://github.com/brillout/vite-plugin-ssr/blob/0.4.0/examples/react/package.json — note how the vite CLI is used together with vite-plugin-ssr. (The prod script is a misnomer used for vps's CI.). You may also want to watch this PR #7665.

Rebased & added some code comments.

Note: This PR is in the team discussion board. We'll try to get to it soon!

@brillout we discussed today this proposal, we think it is a good idea. Would you rebase the PR? Then we are good to merge it.

Done.

Btw. I'm not forgetting to resurrect the $ vite preview SSR fix, I'll just do it after the vite-plugin-ssr 0.4 release.

Note: This PR is in the team discussion board. We'll try to get to it soon!

Thanks for the update, that was super helpful :-).

Btw. I'm not forgetting to resurrect the $ vite preview SSR fix, I'll just do it after the vite-plugin-ssr 0.4 release.

I couldn't contain myself: #8061 :-).