How to build the docker image to run the websocket server in nodejs

First we need to create the websocket server using below code. We also need to create package.json file which should include the dependency - ws

// websocket-server.js
const WebSocket = require('ws');

const wss = new WebSocket.Server({ port: 8080 });

wss.on('connection', function connection(ws) {
  console.log('A new client connected');

  ws.on('message', function incoming(message) {
    console.log('Received message:', message);
    ws.send(`Echo: ${message}`);
  });

  ws.on('close', function close() {
    console.log('Client disconnected');
  });
});

console.log('WebSocket server running on ws://localhost:8080');

Create Dockerfile

Then you need to create a docker file as below.

	# Dockerfile
	FROM node:14

	# Create app directory
	WORKDIR /app

	# Copy package.json and package-lock.json
	COPY package*.json ./

	# Install app dependencies
	RUN npm install

	# Bundle app source
	COPY . .

	# Expose the WebSocket port
	EXPOSE 8080

	# Command to run the WebSocket server
	CMD ["node", "main.js"]									

Build Docker image

	docker build -t websocket-server .				

Start the container

       docker run -p 8081:8080 websocket-server

Access the web socket server at ws://localhost:8081