Run in Cloudflare Worker + Durable Object

[jokester]

I am interested by serverless websocket server and cost saving (via WebSocket Hibernation) CF provide, so I made a PoC / code.

Many pieces are lacking including persisted state, WS Hibernation, clustering or load balancing but it basically works.

I don't have a clear roadmap though, so ideas welcome 🤔

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Update: a working npm package at https://github.com/jokester/socket.io-serverless / https://www.npmjs.com/package/socket.io-serverless .

[jokester]

It won't be easy to make this an official feature of socket.io. To build and run it in CF worker it required quite a few tweaks in socket.io engine.io and other packages.

If a reusable artifact interests other people I guess the easier way is to create a custom socket.io JS bundle.

[darrachequesne]

@jokester I guess what we could do is create an engine based on the Cloudflare WebSocket server, and then bind it to the high-level Socket.IO server.

The engine manages the low-level connections (HTTP long-polling or WebSocket). The engine.io package is one implementation of an engine, based on the Node.js HTTP server: https://github.com/socketio/engine.io

[jokester]

Yes. CF has its own WebSocket impl so code relied on ws or other WS server is not used.

My PoC basically fused CF WebSocket to eio.Socket eio.WebSocket (I only wanted to support websocket transportation) to reuse their code. Above that sio.{Server,Client,Namespace} mostly run likely they do in Node.js 👍🏽

[jokester]

Months later: I think I have a working version now: https://github.com/jokester/socket.io-serverless .

It is based on engine.io (WebSocketTransport) and socket.io (Server / Client / Socket / Namespace / Adapter) code, but rewires a lot to work in Cloudflare Worker , especially to support hibernation / alarm.

I learned a lot making this lol.

[petrbela]

Check out https://www.partykit.io/. It's a WebSocket server built on top of CF/DurableObjects with a TypeScript SDK.