Docker Learning Roadmap for Complete Beginners

Prerequisites - What You Should Know First

Before diving into Docker, you should have:

1. Basic Linux/Command Line Knowledge

• Navigating directories (cd, ls, pwd)
• File operations (cp, mv, rm, mkdir)
• File permissions (chmod, chown)
• Basic text editors (nano, vim)

2. Understanding of Basic Programming

• Any programming language (Python, JavaScript, Java, etc.)
• How applications run on your system
• What dependencies and libraries mean

3. Basic Networking Concepts

• What IP addresses are
• Ports and how applications communicate
• Basic HTTP/web concepts

4. Operating System Basics

• How processes work
• What file systems are
• Environment variables

Don't worry if you're not an expert in these - basic familiarity is enough to get started!

Complete Docker Learning Roadmap

Phase 1: Understanding the "Why" (Week 1)

1. Learn What Problems Docker Solves

• "It works on my machine" problem
• Dependency conflicts
• Environment consistency
• Application isolation

2. Understand Containerization Concepts

• What is a container vs virtual machine?
• How containers differ from traditional deployment
• Benefits of containerization

3. Docker Architecture Basics

• Docker Engine
• Docker Client
• Docker Daemon
• Docker Registry (Docker Hub)

Phase 2: Installation & First Steps (Week 1-2)

1. Install Docker

• Docker Desktop (Windows/Mac)
• Docker Engine (Linux)
• Verify installation with docker --version

2. Run Your First Container

docker run hello-world

• Understand what happened
• Learn about pulling images

3. Basic Docker Commands

• docker ps (list running containers)
• docker ps -a (list all containers)
• docker images (list images)
• docker pull (download images)
• docker stop (stop containers)
• docker rm (remove containers)
• docker rmi (remove images)

Phase 3: Working with Images (Week 2-3)

1. Understanding Docker Images

• What is an image?
• Image layers concept
• Docker Hub exploration
• Official vs community images

2. Pulling and Running Images

• Pull different images (nginx, ubuntu, python)
• Run containers from images
• Interactive mode vs detached mode
• Port mapping with -p flag

3. Basic Container Operations

• Starting and stopping containers
• Accessing container logs (docker logs)
• Executing commands in running containers (docker exec)
• Inspecting containers (docker inspect)

Phase 4: Creating Your Own Images (Week 3-4)

1. Dockerfile Basics

• What is a Dockerfile?
• Basic Dockerfile instructions:
  • FROM (base image)
  • RUN (execute commands)
  • COPY / ADD (add files)
  • WORKDIR (set working directory)
  • CMD (default command)
  • EXPOSE (declare ports)

2. Building Images

• docker build command
• Tagging images
• Understanding build context
• .dockerignore file

3. Best Practices

• Using appropriate base images
• Layer optimization
• Multi-stage builds (intermediate)
• Security considerations

Phase 5: Container Data Management (Week 4-5)

1. Understanding Container Filesystem

• Container ephemeral nature
• Data persistence problem

2. Volumes

• Named volumes
• Creating and managing volumes
• Mounting volumes to containers

3. Bind Mounts

• Difference from volumes
• When to use bind mounts
• Practical use cases (development)

Phase 6: Networking (Week 5-6)

1. Container Networking Basics

• Default bridge network
• How containers communicate
• Port publishing (-p vs -P)

2. Docker Networks

• Creating custom networks
• Network types (bridge, host, none)
• Connecting containers to networks
• Container name resolution

Phase 7: Docker Compose (Week 6-8)

1. Introduction to Docker Compose

• Why use Docker Compose?
• Installing Docker Compose
• YAML syntax basics

2. Writing docker-compose.yml

• Services definition
• Image vs build
• Ports, volumes, networks
• Environment variables
• Dependencies (depends_on)

3. Compose Commands

• docker-compose up
• docker-compose down
• docker-compose logs
• docker-compose ps
• docker-compose exec

4. Multi-Container Applications

• Web app + Database setup
• Service communication
• Managing multiple services

Phase 8: Real-World Projects (Week 8-10)

1. Simple Web Application

• Containerize a Node.js/Python app
• Add a database (MySQL/PostgreSQL)
• Connect them with Compose

2. Development Workflow

• Hot-reload setup
• Development vs production configs
• Using environment files

3. Common Patterns

• NGINX as reverse proxy
• Multi-tier applications
• Microservices basics

Phase 9: Intermediate Topics (Week 10-12)

1. Environment Variables & Secrets

• Passing environment variables
• Using .env files
• Basic secrets management

2. Health Checks

• Container health checks
• Restart policies

3. Resource Limits

• CPU and memory limits
• Monitoring resource usage

4. Docker Registry

• Pushing images to Docker Hub
• Creating private registries

Phase 10: Production Considerations (Advanced)

1. Security

• Running containers as non-root
• Image scanning
• Security best practices

2. Optimization

• Image size reduction
• Build optimization
• Cache management

3. Logging & Monitoring

• Container logging
• Log drivers
• Basic monitoring

Recommended Learning Path Timeline

• Weeks 1-2: Basics and understanding
• Weeks 3-4: Creating images and Dockerfiles
• Weeks 5-6: Data and networking
• Weeks 7-8: Docker Compose
• Weeks 9-12: Projects and practice

Daily Practice Routine

30-60 minutes daily:

1. Learn one new concept (15-20 min)
2. Practice with hands-on exercises (20-30 min)
3. Document what you learned (10 min)

Resources to Use

1. Official Docker Documentation - Best resource
2. Docker Getting Started Tutorial - Interactive learning
3. YouTube Channels: TechWorld with Nana, NetworkChuck
4. Practice Platforms: Play with Docker (labs.play-with-docker.com)

Key Tips for Success

1. Practice Daily - Even 30 minutes helps
2. Build Projects - Don't just watch tutorials
3. Start Simple - Don't jump to complex topics
4. Understand Concepts - Don't just memorize commands
5. Join Communities - Docker subreddit, Discord servers
6. Make Mistakes - Breaking things helps you learn

After mastering Docker basics (first 8-10 weeks), you can explore:

• Docker Swarm (orchestration)
• Kubernetes (advanced orchestration)
• CI/CD integration
• Advanced security and optimization

Start with Phase 1, spend quality time understanding each concept, and practice extensively. Good luck with your Docker learning journey!