Docker Containerization
Learn Docker containerization for Node.js applications including multi-stage builds, optimization, and best practices.
90 minā¢By Priygop Teamā¢Last updated: Feb 2026
Docker Fundamentals
Docker allows you to package applications and their dependencies into lightweight, portable containers that can run consistently across different environments.
Basic Dockerfile
Example
# Basic Dockerfile for Node.js
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 . .
# Expose port
EXPOSE 3000
# Start application
CMD ["npm", "start"]Multi-stage Build
Example
# Multi-stage Dockerfile for optimization
# Build stage
FROM node:18-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build
# Production stage
FROM node:18-alpine AS production
# Create non-root user
RUN addgroup -g 1001 -S nodejs
RUN adduser -S nextjs -u 1001
WORKDIR /app
# Copy built application
COPY --from=builder --chown=nextjs:nodejs /app/dist ./dist
COPY --from=builder --chown=nextjs:nodejs /app/node_modules ./node_modules
COPY --from=builder --chown=nextjs:nodejs /app/package*.json ./
USER nextjs
EXPOSE 3000
CMD ["node", "dist/index.js"]Docker Compose
Example
# docker-compose.yml for full stack application
version: '3.8'
services:
app:
build: .
ports:
- "3000:3000"
environment:
- NODE_ENV=production
- DATABASE_URL=postgresql://user:password@db:5432/myapp
- REDIS_URL=redis://redis:6379
depends_on:
- db
- redis
volumes:
- ./logs:/app/logs
restart: unless-stopped
db:
image: postgres:15-alpine
environment:
- POSTGRES_DB=myapp
- POSTGRES_USER=user
- POSTGRES_PASSWORD=password
volumes:
- postgres_data:/var/lib/postgresql/data
ports:
- "5432:5432"
restart: unless-stopped
redis:
image: redis:7-alpine
ports:
- "6379:6379"
volumes:
- redis_data:/data
restart: unless-stopped
nginx:
image: nginx:alpine
ports:
- "80:80"
volumes:
- ./nginx.conf:/etc/nginx/nginx.conf
depends_on:
- app
restart: unless-stopped
volumes:
postgres_data:
redis_data:Docker Best Practices
- Use multi-stage builds to reduce image size
- Use .dockerignore to exclude unnecessary files
- Run as non-root user for security
- Use specific base image tags
- Minimize layers and combine RUN commands
- Use health checks for container monitoring
Mini-Project: Production Docker Setup
Example
# Complete production Docker setup
# Dockerfile
FROM node:18-alpine AS base
# Install dependencies only when needed
FROM base AS deps
RUN apk add --no-cache libc6-compat
WORKDIR /app
COPY package.json package-lock.json* ./
RUN npm ci --only=production
# Rebuild the source code only when needed
FROM base AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
# Build the application
RUN npm run build
# Production image, copy all the files and run next
FROM base AS runner
WORKDIR /app
ENV NODE_ENV production
RUN addgroup --system --gid 1001 nodejs
RUN adduser --system --uid 1001 nextjs
COPY --from=builder /app/public ./public
COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static
USER nextjs
EXPOSE 3000
ENV PORT 3000
ENV HOSTNAME "0.0.0.0"
CMD ["node", "server.js"]
# .dockerignore
node_modules
npm-debug.log
.next
.git
.env.local
.env.development.local
.env.test.local
.env.production.local
README.md
Dockerfile
.dockerignore
# docker-compose.prod.yml
version: '3.8'
services:
app:
build:
context: .
dockerfile: Dockerfile
ports:
- "3000:3000"
environment:
- NODE_ENV=production
- DATABASE_URL=postgresql://user:password@db:5432/myapp
depends_on:
- db
restart: unless-stopped
healthcheck:
test: ["CMD", "curl", "-f", "http://localhost:3000/health"]
interval: 30s
timeout: 10s
retries: 3
db:
image: postgres:15-alpine
environment:
- POSTGRES_DB=myapp
- POSTGRES_USER=user
- POSTGRES_PASSWORD=password
volumes:
- postgres_data:/var/lib/postgresql/data
restart: unless-stopped
volumes:
postgres_data: