Docker & Containerization

Best practices for Docker and containerized applications.

When to Use

• Containerizing applications
• Writing or optimizing Dockerfiles
• Setting up development or production environments

Dockerfile Best Practices

Multi-Stage Builds

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

# Production stage
FROM node:20-alpine
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/node_modules ./node_modules
EXPOSE 3000
CMD ["node", "dist/index.js"]

Security Practices

# Use specific versions, not latest
FROM python:3.11-slim

# Create non-root user
RUN useradd -m appuser
USER appuser

# Minimize layers and cache
RUN apt-get update && apt-get install -y --no-install-recommends \
    package \
    && rm -rf /var/lib/apt/lists/*

.dockerignore

node_modules
.git
*.log
.env
.DS_Store

Docker Compose

version: '3.8'
services:
  app:
    build: .
    ports:
      - "3000:3000"
    environment:
      - NODE_ENV=production
    depends_on:
      - db
  
  db:
    image: postgres:15-alpine
    volumes:
      - pgdata:/var/lib/postgresql/data

volumes:
  pgdata:

Resources

• Docker Docs
• Dockerfile Best Practices