Containers

Kubernetes is powerful, but it’s also complex. This is my journey of trying to build a “simple” Kubernetes stack and the lessons learned along the way. The Goal I wanted to create a simple, maintainable Kubernetes setup for a small to medium-sized application. The requirements were: Easy to understand and maintain Cost-effective Scalable when needed Developer-friendly What I Started With Initial Stack Kubernetes: EKS (AWS) Ingress: NGINX Ingress Controller Database: Managed PostgreSQL (RDS) Monitoring: Prometheus + Grafana Logging: ELK Stack CI/CD: GitLab CI The Reality Check Complexity Crept In What started as “simple” quickly became complex: ...

Containerized systems have unique failure modes. Here’s how to identify and prevent common issues. 1. Resource Exhaustion Memory Limits # docker-compose.yml services: app: deploy: resources: limits: memory: 512M reservations: memory: 256M CPU Throttling services: app: deploy: resources: limits: cpus: '1.0' 2. Container Restart Loops Health Checks # Dockerfile HEALTHCHECK --interval=30s --timeout=3s --start-period=40s \ CMD curl -f http://localhost:8080/health || exit 1 Restart Policies services: app: restart: unless-stopped # Options: no, always, on-failure, unless-stopped 3. Network Issues Port Conflicts services: app: ports: - "8080:8080" # host:container DNS Resolution services: app: dns: - 8.8.8.8 - 8.8.4.4 4. Volume Mount Problems Permission Issues # Fix permissions RUN chown -R appuser:appuser /app USER appuser Volume Mounts services: app: volumes: - ./data:/app/data:ro # Read-only - cache:/app/cache 5. Image Layer Caching Optimize Dockerfile # Bad: Changes invalidate cache COPY . . RUN npm install # Good: Layer caching COPY package*.json ./ RUN npm install COPY . . 6. Log Management Log Rotation services: app: logging: driver: "json-file" options: max-size: "10m" max-file: "3" 7. Security Issues Non-Root User RUN useradd -m appuser USER appuser Secrets Management services: app: secrets: - db_password environment: DB_PASSWORD_FILE: /run/secrets/db_password Prevention Strategies Set resource limits Implement health checks Use proper restart policies Monitor container metrics Test failure scenarios Use orchestration tools (Kubernetes, Docker Swarm) Conclusion Prevent container failures by: ...

Building efficient Docker images requires following best practices. Here’s how. 1. Use Multi-Stage Builds # Build stage FROM node:18 AS builder WORKDIR /app COPY package*.json ./ RUN npm ci COPY . . RUN npm run build # Production stage FROM node:18-alpine WORKDIR /app COPY --from=builder /app/dist ./dist COPY --from=builder /app/node_modules ./node_modules CMD ["node", "dist/index.js"] 2. Layer Caching # Bad: Changes invalidate cache COPY . . RUN npm install # Good: Dependencies cached COPY package*.json ./ RUN npm install COPY . . 3. Use .dockerignore node_modules .git .env dist *.log 4. Minimize Layers # Bad: Multiple layers RUN apt-get update RUN apt-get install -y python RUN apt-get install -y git # Good: Single layer RUN apt-get update && \ apt-get install -y python git && \ rm -rf /var/lib/apt/lists/* 5. Use Specific Tags # Bad: Latest tag FROM node:latest # Good: Specific version FROM node:18.17.0-alpine Best Practices Multi-stage builds Optimize layer order Use .dockerignore Minimize image size Security scanning Conclusion Build efficient Docker images! 🐳