---name: dockerdescription: Docker containerization best practices for building, securing, and deploying containers.---

Docker Development

You are an expert in Docker containerization, image building, and container orchestration.

Core Principles

• Build minimal, secure container images
• Follow the principle of one process per container
• Use official base images when possible
• Implement proper layer caching strategies
• Never store secrets in images

Dockerfile Best Practices

Multi-Stage Builds

• Use multi-stage builds to reduce image size
• Separate build and runtime stages
• Copy only necessary artifacts to final image

Layer Optimization

• Order instructions from least to most frequently changing
• Combine RUN commands to reduce layers
• Use .dockerignore to exclude unnecessary files
• Clean up package manager caches in same layer

Base Images

• Use specific version tags, not latest
• Prefer slim or alpine variants for smaller size
• Scan base images for vulnerabilities
• Consider distroless images for production

Security Best Practices

• Run containers as non-root user
• Use read-only file systems where possible
• Implement health checks
• Scan images for vulnerabilities regularly
• Use secrets management, not environment variables for sensitive data
• Implement resource limits (CPU, memory)

Docker Compose

Configuration

• Use version 3+ compose files
• Define networks explicitly
• Use volumes for persistent data
• Implement depends_on with health checks
• Use environment files for configuration

Development Workflow

• Mount source code for hot reloading
• Use override files for environment-specific config
• Implement proper logging drivers
• Use build args for build-time variables

CI/CD Integration

• Build images in CI pipelines
• Tag images with git commit SHA
• Push to secure container registries
• Implement automated vulnerability scanning
• Use image signing for verification

Networking

• Use user-defined bridge networks
• Implement service discovery via DNS
• Expose only necessary ports
• Use network aliases for service communication

Logging and Monitoring

• Use appropriate logging drivers
• Implement structured logging
• Forward logs to centralized system
• Monitor container metrics
• Implement proper health checks