docker-setup

## Purpose Package applications and their dependencies into containers for consistent deployment across environments. ## When to Use - Containerizing applications - Creating reproducible development environments - Setting up microservices - Deploying to production - Isolating dependencies ## Installation ### Linux ```bash curl -fsSL https://get.docker.com -o get-docker.sh sudo sh get-docker.sh sudo usermod -aG docker $USER ``` ### macOS ```bash # Install Docker Desktop brew install --cask docker ``` ### Windows ```bash # Install Docker Desktop from https://docker.com/products/docker-desktop ``` ## Dockerfile Basics ### Simple Node.js App ```dockerfile FROM node:20-alpine WORKDIR /app COPY package*.json ./ RUN npm install COPY . . EXPOSE 3000 CMD ["npm", "start"] ``` ### Python App ```dockerfile FROM python:3.11-slim WORKDIR /app COPY requirements.txt . RUN pip install --no-cache-dir -r requirements.txt COPY . . EXPOSE 8000 CMD ["python", "app.py"] ``` ### Multi-stage Build ```dockerfile # Build stage FROM node:20-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm install COPY . . RUN npm run build # Production stage FROM node:20-alpine AS production WORKDIR /app COPY --from=builder /app/dist ./dist COPY package*.json ./ RUN npm install --production EXPOSE 3000 CMD ["node", "dist/index.js"] ``` ## Common Dockerfile Patterns ### React App ```dockerfile FROM node:20-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm install COPY . . RUN npm run build FROM nginx:alpine COPY --from=builder /app/build /usr/share/nginx/html EXPOSE 80 CMD ["nginx", "-g", "daemon off;"] ``` ### Next.js App ```dockerfile FROM node:20-alpine AS builder WORKDIR /app COPY package*.json ./ RUN npm install COPY . . RUN npm run build FROM node:20-alpine AS runner WORKDIR /app ENV NODE_ENV production COPY --from=builder /app/public ./public COPY --from=builder /app/.next/standalone ./ COPY --from=builder /app/.next/static ./.next/static EXPOSE 3000 CMD ["node", "server.js"] ``` ### Go App ```dockerfile FROM golang:1.21-alpine AS builder WORKDIR /app COPY go.mod go.sum ./ RUN go mod download COPY . . RUN CGO_ENABLED=0 go build -o app FROM alpine:latest WORKDIR /root/ COPY --from=builder /app/app . EXPOSE 8080 CMD ["./app"] ``` ## Docker Compose ### Basic Web App + Database ```yaml version: '3.8' services: app: build: . ports: - "3000:3000" environment: - DATABASE_URL=postgres://user:pass@db:5432/mydb depends_on: - db db: image: postgres:15-alpine environment: - POSTGRES_USER=user - POSTGRES_PASSWORD=pass - POSTGRES_DB=mydb volumes: - postgres_data:/var/lib/postgresql/data volumes: postgres_data: ``` ### Development Environment ```yaml version: '3.8' services: app: build: . volumes: - .:/app - /app/node_modules ports: - "3000:3000" environment: - NODE_ENV=development command: npm run dev ``` ### Multi-Service Setup ```yaml version: '3.8' services: frontend: build: ./frontend ports: - "3000:3000" backend: build: ./backend ports: - "8000:8000" environment: - DATABASE_URL=postgres://user:pass@db:5432/mydb db: image: postgres:15-alpine environment: - POSTGRES_USER=user - POSTGRES_PASSWORD=pass - POSTGRES_DB=mydb volumes: - postgres_data:/var/lib/postgresql/data redis: image: redis:7-alpine ports: - "6379:6379" volumes: postgres_data: ``` ## Docker Compose Commands ```bash # Start services docker-compose up # Start in detached mode docker-compose up -d # Stop services docker-compose down # Rebuild and start docker-compose up --build # View logs docker-compose logs -f # Execute command in container docker-compose exec app sh # View running containers docker-compose ps # Remove volumes docker-compose down -v ``` ## Docker Commands ### Images ```bash # Build image docker build -t myapp:1.0 . # List images docker images # Remove image docker rmi myapp:1.0 # Pull image docker pull node:20-alpine # Push image docker push myrepo/myapp:1.0 ``` ### Containers ```bash # Run container docker run -p 3000:3000 myapp:1.0 # Run in detached mode docker run -d -p 3000:3000 myapp:1.0 # List containers docker ps # Stop container docker stop <container-id> # Remove container docker rm <container-id> # Execute command docker exec -it <container-id> sh ``` ### Volumes ```bash # Create volume docker volume create myvolume # List volumes docker volume ls # Remove volume docker volume rm myvolume ``` ### Networks ```bash # Create network docker network create mynetwork # List networks docker network ls # Connect container to network docker network connect mynetwork mycontainer ``` ## Best Practices ### Dockerfile - Use specific base image tags (not `latest`) - Use multi-stage builds for smaller images - Combine RUN commands to reduce layers - Use .dockerignore to exclude files - Run as non-root user when possible - Set HEALTHCHECK for monitoring - Use build args for configuration ### Docker Compose - Use version 3.8+ for compatibility - Define volumes for persistent data - Use environment variables for configuration - Set resource limits - Use depends_on for service dependencies - Use restart policies for production ### Security - Scan images for vulnerabilities - Use official base images - Keep images updated - Don't run as root - Use secrets management - Limit container capabilities ## .dockerignore ``` node_modules npm-debug.log .git .env .DS_Store coverage .next dist build *.log ``` ## Common Issues ### Container Won't Start ```bash # Check logs docker logs <container-id> # Check if port is in use netstat -tulpn | grep <port> # Check container status docker ps -a ``` ### Out of Space ```bash # Remove unused images docker image prune -a # Remove unused containers docker container prune # Remove unused volumes docker volume prune # Remove everything unused docker system prune -a ``` ### Permission Issues ```bash # Add user to docker group sudo usermod -aG docker $USER # Fix file permissions docker run -u $(id -u):$(id -g) ... ``` ## Production Deployment ### Docker Registry ```bash # Login to registry docker login registry.example.com # Tag image docker tag myapp:1.0 registry.example.com/myapp:1.0 # Push image docker push registry.example.com/myapp:1.0 ``` ### Docker Swarm ```bash # Initialize swarm docker swarm init # Deploy stack docker stack deploy -c docker-compose.yml mystack # List services docker service ls # Scale service docker service scale mystack_app=3 ``` ### Kubernetes (using Kompose) ```bash # Install kompose curl -L https://github.com/kubernetes/kompose/releases/download/v1.28.0/kompose-linux-amd64 -o kompose chmod +x kompose sudo mv kompose /usr/local/bin/ # Convert docker-compose to kubernetes kompose convert # Apply to kubernetes kubectl apply -f . ``` ## Scripts ### build.sh ```bash #!/bin/bash docker build -t myapp:$(git rev-parse --short HEAD) . ``` ### deploy.sh ```bash #!/bin/bash docker-compose down docker-compose up -d --build docker-compose logs -f ``` ### clean.sh ```bash #!/bin/bash docker-compose down -v docker system prune -a ```