Docker Containerization
Learn to containerize Node.js applications using Docker. This is a foundational concept in server-side JavaScript development that professional developers rely on daily. The explanations below are written to be beginner-friendly while covering the depth and nuance that comes from real-world Node.js experience. Take your time with each section and practice the examples
Docker Basics
Docker is a platform for developing, shipping, and running applications in containers. It provides a consistent environment across different machines and makes deployment easier.. This is an essential concept that every Node.js developer must understand thoroughly. In professional development environments, getting this right can mean the difference between code that works reliably and code that breaks in production. The following sections break this down into clear, digestible pieces with practical examples you can try immediately
Dockerfile for Node.js
# Use official Node.js runtime as base image
FROM node:18-alpine
# Set working directory
WORKDIR /app
# Copy package files
COPY package*.json ./
# Install dependencies
RUN npm ci --only=production
# Copy application code
COPY . .
# Create non-root user
RUN addgroup -g 1001 -S nodejs
RUN adduser -S nextjs -u 1001
# Change ownership
RUN chown -R nextjs:nodejs /app
USER nextjs
# Expose port
EXPOSE 3000
# Health check
HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
CMD curl -f http://localhost:3000/health || exit 1
# Start application
CMD ["npm", "start"]
# Docker Compose example
# docker-compose.yml
version: '3.8'
services:
app:
build: .
ports:
- "3000:3000"
environment:
- NODE_ENV=production
- MONGODB_URI=mongodb://mongo:27017/myapp
depends_on:
- mongo
restart: unless-stopped
mongo:
image: mongo:5.0
ports:
- "27017:27017"
volumes:
- mongo_data:/data/db
restart: unless-stopped
volumes:
mongo_data: