Docker Containerization Patterns

Build efficient, secure Docker images using modern patterns.

Multi-Stage Builds

Always use multi-stage builds to minimize image size:

# Build stage
FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci --only=production

# Production stage
FROM node:20-alpine
WORKDIR /app
COPY --from=builder /app/node_modules ./node_modules
COPY . .
USER node
CMD ["node", "server.js"]

Security Best Practices

1. Never run as root - use USER directive
2. Use specific version tags, not latest
3. Scan images with docker scout or Trivy
4. Use .dockerignore to exclude sensitive files

Health Checks

HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
  CMD curl -f http://localhost:3000/health || exit 1

Compose Patterns

services:
  app:
    build:
      context: .
      target: production
    environment:
      - NODE_ENV=production
    deploy:
      resources:
        limits:
          memory: 512M