Docker Containers Learning Repository

Welcome! This repository is designed to help you learn Docker and build containers in a consistent environment using GitHub Codespaces, regardless of whether you're on Windows, macOS, or Linux.

🚀 Quick Start

Using GitHub Codespaces (Recommended)

1. Open in Codespaces

   • Click the green "Code" button at the top of this repository
   • Select "Codespaces" tab
   • Click "Create codespace on main"
   • Wait for the environment to set up (1-2 minutes)

2. Verify Docker Installation

   docker --version
   docker compose version

3. You're Ready! Docker and Docker Compose are pre-installed and configured.

⚠️ Important: If you get a "permission denied" error when running Docker commands, see the Troubleshooting Guide or rebuild your container: Command Palette → "Codespaces: Rebuild Container"

Alternative: Local Development

If you prefer to work locally, you'll need:

• Docker Desktop (Windows/macOS)
• Docker Engine (Linux)
• VS Code with the Dev Containers extension

📚 Examples Included

This repository includes several example projects to get you started:

1. Simple Web Server (examples/simple-web/)

A basic nginx web server serving a custom HTML page.

cd examples/simple-web
docker build -t simple-web .
docker run -d -p 8080:80 simple-web

Then open the forwarded port to see your web page!

2. Python Application (examples/python-app/)

A Python web application.

cd examples/python-app
docker build -t python-app .
docker run -d -p 8000:8000 python-app

3. Multi-Container App with Docker Compose (examples/docker-compose-example/)

A multi-service application with Flask and Redis.

cd examples/docker-compose-example
docker compose up -d

To stop:

docker compose down

🛠️ Common Docker Commands

Building Images

# Build an image from a Dockerfile
docker build -t my-image-name .

# Build with a specific Dockerfile
docker build -t my-image -f Dockerfile.dev .

Running Containers

# Run a container
docker run my-image-name

# Run in detached mode (background)
docker run -d my-image-name

# Run with port mapping
docker run -p 8080:80 my-image-name

# Run with volume mount
docker run -v $(pwd):/app my-image-name

# Run with environment variables
docker run -e MY_VAR=value my-image-name

Managing Containers

# List running containers
docker ps

# List all containers (including stopped)
docker ps -a

# Stop a container
docker stop container-id

# Remove a container
docker rm container-id

# View container logs
docker logs container-id

# Execute command in running container
docker exec -it container-id bash

Managing Images

# List images
docker images

# Remove an image
docker rmi image-id

# Pull an image from Docker Hub
docker pull nginx:latest

# Tag an image
docker tag my-image:latest my-image:v1.0

Docker Compose Commands

# Start services
docker compose up

# Start in background
docker compose up -d

# Stop services
docker compose down

# View logs
docker compose logs

# Rebuild services
docker compose up --build

Cleanup Commands

# Remove all stopped containers
docker container prune

# Remove all unused images
docker image prune

# Remove all unused volumes
docker volume prune

# Remove everything unused
docker system prune -a

📝 Creating Your Own Dockerfile

Here's a template to get you started:

# Choose a base image
FROM ubuntu:latest

# Set working directory
WORKDIR /app

# Copy files
COPY . .

# Install dependencies
RUN apt-get update && apt-get install -y \
    package-name \
    && rm -rf /var/lib/apt/lists/*

# Expose port (documentation only)
EXPOSE 8080

# Set environment variables
ENV MY_VAR=value

# Run command when container starts
CMD ["executable", "param1", "param2"]

🎯 Learning Path

1. Start with Simple Web - Learn basic Docker commands and image building
2. Try Python App - Understand multi-step builds and dependencies
3. Explore Docker Compose - Learn to orchestrate multiple containers
4. Create Your Own - Build something custom!

🔧 Troubleshooting

Port Already in Use

If you get a "port already in use" error:

# Find what's using the port
docker ps

# Stop the container using that port
docker stop container-id

Container Won't Start

Check the logs:

docker logs container-id

Out of Space

Clean up unused resources:

docker system prune -a

Can't Connect to Docker Daemon

In Codespaces, Docker should work automatically. If you have issues:

# Check Docker is running
docker ps

# Restart the codespace if needed

📖 Additional Resources

• Docker Documentation
• Docker Hub - Find pre-built images
• Dockerfile Best Practices
• Docker Compose Documentation

🤝 Contributing

Feel free to add your own examples! Create a new folder under examples/ with:

• A Dockerfile
• A README.md explaining what it does
• Any necessary application files

💡 Tips for Success

1. Always use .dockerignore - Similar to .gitignore, exclude unnecessary files
2. Keep images small - Use alpine or slim base images when possible
3. One process per container - Follow the single responsibility principle
4. Use multi-stage builds - For smaller production images
5. Don't run as root - Create a user in your Dockerfile for security
6. Tag your images - Use meaningful version tags, not just latest

🐳 Happy Containerizing!

Remember: The beauty of Codespaces is that everyone gets the exact same environment. No more "it works on my machine" problems!

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Questions? Open an issue or reach out to the repository maintainer.