A fun and educational CLI-based chat system using Docker, Node.js, Redis, and NGINX load balancing — each container acts like a chatroom! Practice service discovery, internal networking, stateful containers, and load balancing all in one project.
- Two chat rooms (Node.js servers)
- Central Redis database for message storage
- Nginx as a load balancer for routing messages
- A client container to send chat messages via CLI
- Messages stored in Redis per room (
messages:room1,messages:room2)
docker-chat-network/ │ ├── docker-compose.yml │ ├── chatroom1/ │ ├── Dockerfile │ └── server.js │ ├── chatroom2/ │ ├── Dockerfile │ └── server.js │ ├── redis-client/ │ ├── Dockerfile │ ├── package.json │ └── client.js │ └── nginx/ ├── Dockerfile └── default.conf
We'll use:
Node.js for chat servers (lightweight, good socket/HTTP support). Redis to store chats (fast, simple key-value). nginx as load balancer. Docker Compose to manage it all.
📁 Step 1: Create Directory Structure Open your terminal and run:
mkdir docker-chat-network cd docker-chat-network
🧩 Inside chatroom1 Run:
✍️ Add server.js // server.js const express = require('express'); const axios = require('axios'); const Redis = require('redis');
const app = express();
const port = process.env.PORT || 3000;
const ROOM = process.env.ROOM || "room1";
const REDIS_HOST = process.env.REDIS_HOST || "redis";
const client = Redis.createClient({ url: redis://${REDIS_HOST}:6379 });
app.use(express.json());
client.connect().catch(console.error);
app.post('/message', async (req, res) => {
const { message } = req.body;
await client.rPush(messages:${ROOM}, message);
console.log([${ROOM}] Received: ${message});
res.send([${ROOM}] Message stored);
});
app.get('/messages', async (req, res) => {
const messages = await client.lRange(messages:${ROOM}, 0, -1);
res.json(messages);
});
app.listen(port, () => {
console.log([${ROOM}] listening on port ${port});
});
🐳 Dockerfile for chatroom
FROM node:18-alpine WORKDIR /app COPY package*.json ./ RUN npm install COPY . . CMD ["node", "server.js"]
📦 Step 4: Redis Client Setup (redis-client)
cd redis-client touch client.js Dockerfile package.json npm init -y npm install axios readline-sync
✍️ client.js const axios = require('axios'); const readline = require('readline-sync');
const targets = ['http://nginx']; // nginx load balances to rooms
async function main() {
while (true) {
const message = readline.question("Enter message: ");
await axios.post(${targets[0]}/message, { message });
console.log("Message sent!\n");
}
}
main();
🌐 Step 5: NGINX as Load Balancer
🔧 nginx/default.conf upstream chatrooms { server chatroom1:3000; server chatroom2:3000; }
server { listen 80;
location / {
proxy_pass http://chatrooms;
}
}
🐳 nginx/Dockerfile FROM nginx:alpine COPY default.conf /etc/nginx/conf.d/default.conf
📋 Step 6: docker-compose.yml
version: "3.9"
services: redis: image: redis ports: - "6379:6379"
nginx: image: nginx:alpine ports: - "8080:80" volumes: - ./nginx.conf:/etc/nginx/conf.d/default.conf depends_on: - chatroom1 - chatroom2
chatroom1: build: context: ./chatroom1 environment: - ROOM=room1 - REDIS_HOST=redis depends_on: - redis
chatroom2: build: context: ./chatroom2 environment: - ROOM=room2 - REDIS_HOST=redis depends_on: - redis
client: build: context: ./client stdin_open: true tty: true
🚀 Step 7: Run Everything
From root (docker-chat-network/), run:
docker-compose up --build
✅ Step 3: Add More Features (Optional for Fun)
You can now enhance the chat system:
🎨 Cool Ideas: Add chatroom names (/room city, /room friends) Include timestamps Use WebSockets (e.g. Socket.IO) for real-time messaging Add a frontend: simple HTML page with JS to send/receive messages Persist chat to MongoDB (for history)
docker exec -it docker-chat-network-client-1 node client.js
docker exec -it redis redis-cli
docker logs -f docker-chat-network-chatroom1-1 docker logs -f docker-chat-network-chatroom2-1
🤖 Author
Syed Owais Ahmed GitHub: @devopsbyowais
👍🏻THE END >>