Docker containerization for Node.js in Node.js - Mini Project: Build & Apply

Docker containerization for Node.js

📖 Scenario: You are building a simple Node.js app that says hello. You want to package it inside a Docker container so it can run anywhere easily.

🎯 Goal: Create a Docker container for a Node.js app that listens on port 3000 and responds with 'Hello from Docker!'.

📋 What You'll Learn

Create a basic Node.js app with Express that listens on port 3000

Add a configuration variable for the port number

Write a Dockerfile to containerize the app

Run the app inside the Docker container exposing port 3000

💡 Why This Matters

🌍 Real World

Docker lets developers package apps with all dependencies so they run the same on any computer or server.

💼 Career

Knowing Docker containerization is essential for modern backend and full-stack developers to deploy and manage applications efficiently.

1

Create the Node.js app

Create a file called app.js with these exact lines: import express, create an app, and add a route / that sends the text 'Hello from Docker!'. Then make the app listen on port 3000.

Node.js

# Your code here to create app.js with express, route, and listen on port 3000

Need a hint?

Use import express from 'express' and app.get for the route.

2

Add a port configuration variable

Add a constant called PORT and set it to 3000. Change the app.listen call to use this PORT variable.

Node.js

import express from 'express';
const app = express();

app.get('/', (req, res) => {
  res.send('Hello from Docker!');
});

// Define PORT variable and use it in app.listen
# Your code here

Need a hint?

Define const PORT = 3000 and use app.listen(PORT).

3

Write the Dockerfile

Create a file called Dockerfile with these exact lines: start from node:18-alpine image, set working directory to /app, copy package*.json and app.js into the container, run npm install, expose port 3000, and run the app with node app.js.

Node.js

# Your Dockerfile content here

Need a hint?

Use FROM node:18-alpine and CMD ["node", "app.js"].

4

Run the Docker container

Write the exact Docker command to build an image named node-hello from the current directory, then write the command to run a container from node-hello exposing port 3000 on the host.

Node.js

# Your Docker build and run commands here

Need a hint?

Use docker build -t node-hello . and docker run -p 3000:3000 node-hello.