How to Dockerize a Node.js App for Production

Meta Description: Learn how to Dockerize a Node.js app for production step-by-step. This beginner-friendly guide helps junior developers and self-taught coders deploy their apps with ease.

🚀 Introduction

Docker is a game-changer for developers. It allows you to package your application and its dependencies into a lightweight, portable container—making it easier to deploy anywhere. If you’re a junior developer, student, or self-taught coder, this post will walk you through Dockerizing a Node.js app for production—step by step.

By the end of this tutorial, you’ll have a working Docker setup that runs your Node.js app like a pro.

🛠️ What You’ll Need

• Node.js installed
• Basic understanding of Node.js and Express
• Docker installed [Install Docker →]
• A simple Node.js project

📁 Step 1: Create a Simple Node.js App

Folder Structure:

my-node-app/
├── Dockerfile
├── package.json
├── package-lock.json
└── index.js

index.js

const express = require('express');
const app = express();
const PORT = process.env.PORT || 3000;

app.get('/', (req, res) => {
  res.send('Hello from Dockerized Node.js App!');
});

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

package.json

{
  "name": "my-node-app",
  "version": "1.0.0",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "dependencies": {
    "express": "^4.18.2"
  }
}

Run npm install to install dependencies.

🐳 Step 2: Write the Dockerfile

Now, let’s create a Dockerfile to define how your app should be built inside a container.

Dockerfile

# Use official Node.js LTS base image
FROM node:20-alpine

# Set working directory
WORKDIR /app

# Copy package files first (for caching)
COPY package*.json ./

# Install dependencies
RUN npm ci --omit=dev

# Copy app files
COPY . .

# Expose port
EXPOSE 3000

# Start the app
CMD ["npm", "start"]

📝 Note: Using npm ci and --omit=dev improves performance and ensures only production dependencies are installed.

📦 Step 3: Create a .dockerignore File

Just like .gitignore, Docker also supports .dockerignore to avoid copying unnecessary files.

.dockerignore

node_modules
npm-debug.log
Dockerfile
.dockerignore
.git

This keeps your image lean and clean.

🧪 Step 4: Build the Docker Image

Run the following command in the root of your project:

docker build -t my-node-app .

• -t is used to name the image (tag).
• The . tells Docker to look for the Dockerfile in the current directory.

🚀 Step 5: Run the Docker Container

Start the app inside a container:

docker run -d -p 8080:3000 my-node-app

• -d runs it in detached mode.
• -p maps port 8080 on your machine to port 3000 in the container.

Now visit http://localhost:8080 and you’ll see your app running inside Docker! 🎉