golang-realtime-chat

Simple realtime chat built with a Go WebSocket backend and a React frontend. No database — all state is kept in memory for teaching/demo purposes.

What’s inside

• Go backend (apps/backend): HTTP server + WebSocket chat hub (join/leave, broadcast, user IDs)
• Web frontend (apps/web): Minimal chat UI (connect, send, users list)

Prerequisites

• Go (1.21+ recommended)
• Bun or Node.js (for the web app)

Run the backend

cd apps/backend
go mod tidy
go run .
# backend runs on http://localhost:8080

Configure and run the frontend

cd apps/web
cp .env.example .env
# edit .env and set the backend URL (defaults shown)
# VITE_BACKEND_URL=http://localhost:8080

bun install   # or npm install / pnpm install / yarn
bun dev       # or npm run dev / pnpm dev / yarn dev
# frontend runs on http://localhost:3001 (per your dev setup)

How to use

1. Start the backend, then the frontend
2. Open the web app in multiple tabs
3. Enter a username and Connect
4. Send messages; see join/leave and broadcasts in realtime

Backend endpoints

• GET /healthz — health check
• GET /api/users — list of connected users and IDs
• GET /api/stats — basic server stats
• WS /ws?username=YourName — WebSocket chat endpoint

Concepts demonstrated (for workshops)

• Explicit error handling in Go (value, err)
• Goroutines + channels for concurrency
• WebSocket lifecycle (upgrade, read/write pumps, heartbeats)
• In‑memory hub pattern for broadcast and membership

Notes

• IDs are simple incrementing numbers for clarity in demos
• All state is ephemeral; restarting the backend resets the room