hono vite dev server doesn't allow websockets to connect

[benjamine]

I followed the guide at https://hono.dev/docs/getting-started/cloudflare-pages and then added websockets following https://hono.dev/docs/helpers/websocket see repo here: https://github.com/benjamine/hono-vite-websocket (made to reproduce this)

websocket never connects when running the vite dev server (I think because there's never a server upgrade).

websocket works correclty when using vite build+preview or when deployed to cloudflare.

reproduction steps:

• clone the repo
• npm i && npm run dev
• check the console or network tab, note that the browser's websocket never connects

I noticed connection succeeds adding an upgrade handler at the vite plugin

	configureServer(server) {
                ...
		server.httpServer?.on("upgrade", (request, socket, head) => {
                     ...
                     // handle this similarly to hono-node/ws ?

and confirmed that makes the connecting succeed (but this might not be the right way or place to handle it).

[benjamine]

in case it helps, also a temporary workaround: https://github.com/benjamine/hono-vite-websocket/compare/main...node-secondary-ws-server (starting a secondary node server for websockets, something that can be done conditionally when running in local dev)

[yusukebe]

Hi @benjamine

Sorry, I'm late.

If you use Vite for Cloudflare Workers, we currently recommend using @cloudlare/vite-plugin. With it, WebSockets will work well. For example, install it and apply the diff on your repo:

diff --git a/vite.config.ts b/vite.config.ts
index 3dd8bdc..930cb7e 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -3,17 +3,11 @@ import { defineConfig } from 'vite'
 import build from '@hono/vite-cloudflare-pages'
 import devServer from '@hono/vite-dev-server'
 import adapter from '@hono/vite-dev-server/cloudflare'
+import { cloudflare } from '@cloudflare/vite-plugin'

 // import { cloudflare } from '@cloudflare/vite-plugin'
 // import ssrHotReload from 'vite-plugin-ssr-hot-reload'

 export default defineConfig({
-  plugins: [
-    // ssrHotReload(), cloudflare()
-    devServer({
-      entry: 'src/index.tsx',
-      adapter, // Cloudflare Adapter
-    }),
-    build(),
-  ]
+  plugins: [cloudflare()]
 })

@cloudflare/vite-plugin is great!

However, this is only applicable for Cloudflare Workers, so I don't have a solid suggestion for other platforms. Using WebSockets with Vite can be complex. Your workaround is excellent. It would be better if you applied it to other platforms.