Docker Reference

Docker is a platform for developing, shipping, and running applications in containers. This section provides comprehensive command references for working with Docker.

Quick Navigation

Section	Description
Images	Pull, list, remove, and manage Docker images
Containers	Create, run, manage, and debug containers
Compose	Multi-container applications with Docker Compose

Common Workflows

Quick Container Setup

# Pull an image
docker pull ubuntu:latest

# Create and run a container
docker run -it --name myapp ubuntu:latest /bin/bash

# Verify running containers
docker container list

Development Workflow

# Start development containers
docker-compose up -d

# View logs
docker-compose logs -f

# Execute commands in running container
docker-compose exec app bash

# Stop containers
docker-compose down

Cleanup

# Remove stopped containers
docker container prune

# Remove unused images
docker image prune -a

# Clean everything (use with caution)
docker system prune -a --volumes

Installation

Linux

# Install Docker using convenience script
curl -fsSL https://get.docker.com -o get-docker.sh
sudo sh get-docker.sh

# Add user to docker group (to run without sudo)
sudo usermod -aG docker $USER

# Start Docker service
sudo systemctl start docker
sudo systemctl enable docker

macOS

Download and install Docker Desktop for Mac.

Windows

Download and install Docker Desktop for Windows.

Essential Commands

System Information

# Docker version
docker --version

# System information
docker info

# Disk usage
docker system df

Quick Reference

Task	Command
List images	docker image list
List containers	docker container list --all
View logs	docker logs <container>
Execute command	docker exec -it <container> <command>
Clean system	docker system prune

Best Practices

Security

1. Don't run containers as root: Use USER directive in Dockerfile
2. Scan images for vulnerabilities: Use docker scan <image>
3. Use official images: Pull from verified publishers when possible
4. Keep images updated: Regularly update base images

Performance

1. Use .dockerignore: Exclude unnecessary files from build context
2. Multi-stage builds: Reduce final image size
3. Layer caching: Order Dockerfile commands for optimal caching
4. Minimize layers: Combine RUN commands where appropriate

Organization

1. Tag images properly: Use semantic versioning
2. Clean up regularly: Remove unused images and containers
3. Use docker-compose: Manage multi-container applications
4. Document configurations: Add comments to Dockerfiles and compose files

Troubleshooting

Container Won't Start

# Check logs for errors
docker logs <container>

# Inspect container configuration
docker inspect <container>

# Try running interactively
docker run -it <image> /bin/bash

Permission Denied Errors

# Linux: Add user to docker group
sudo usermod -aG docker $USER

# Then log out and log back in

Out of Disk Space

# Check disk usage
docker system df

# Clean up
docker system prune -a --volumes

See Also

• Docker Images - Detailed image management
• Docker Containers - Container operations
• Docker Compose - Multi-container orchestration
• .NET Core Commands - Publishing .NET apps to Docker

External Resources

• Docker Documentation
• Docker Hub - Public image registry
• Dockerfile Reference
• Docker Compose Documentation