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