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Docker Installation Lab - Container Runtime Setup

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Lab: Docker Installation on Ubuntu/Debian

Objective: Install and configure Docker Engine for container-based development and deployment

Difficulty: Beginner

Time to Complete: 15-30 minutes

INFO

Theory Path: This lab supports the Container Fundamentals Path - complete that first for foundational knowledge.

Prerequisites

Knowledge Requirements

  • Basic Linux command line navigation
  • Understanding of package management (apt)
  • Familiarity with sudo/root permissions

Hardware/Software Requirements

  • Hardware: 2GB RAM minimum, 10GB free disk space
  • Software: Ubuntu 18.04+, Debian 10+, or compatible distribution
  • Network: Internet access for package downloads
  • Lab Environment: Physical machine, VM, or LXC container with nested virtualization

Learning Outcomes

After completing this lab, you will be able to:

  1. Install Docker Engine using the official APT repository
  2. Configure Docker to run without sudo (optional)
  3. Validate Docker installation with test containers
  4. Understand Docker security considerations for homelab use

Lab Steps

Step 1: System Preparation

Update your package list and install prerequisites for Docker’s APT repository.

# Update package database
sudo apt update
 
# Install packages for HTTPS repository access
sudo apt install -y ca-certificates curl

Expected Output:

Reading package lists... Done
Building dependency tree... Done
ca-certificates is already the newest version
curl is already the newest version

Troubleshooting:

  • Network error: Check internet connectivity and DNS resolution
  • Permission denied: Ensure you have sudo access

Step 2: Add Docker’s Official GPG Key

Add Docker’s GPG key to verify package authenticity.

# Create keyrings directory
sudo install -m 0755 -d /etc/apt/keyrings
 
# Download and add Docker's GPG key
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc

Expected Output:

(No output expected - commands complete silently on success)

Step 3: Add Docker APT Repository

Configure the Docker repository for your system architecture.

# Add Docker repository to APT sources
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
  $(. /etc/os-release && echo "${UBUNTU_CODENAME:-$VERSION_CODENAME}") stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
 
# Update package database with new repository
sudo apt update

Expected Output:

Hit:1 https://download.docker.com/linux/ubuntu jammy InRelease
Reading package lists... Done

Step 4: Install Docker Engine

Install Docker Engine, CLI, and related components.

# Install Docker packages
sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Expected Output:

The following NEW packages will be installed:
  containerd.io docker-buildx-plugin docker-ce docker-ce-cli docker-compose-plugin
Setting up docker-ce ...

Step 5: Start and Enable Docker Service

Ensure Docker starts automatically on boot.

# Start Docker service
sudo systemctl start docker
 
# Enable Docker to start on boot
sudo systemctl enable docker

Expected Output:

Synchronizing state of docker.service with SysV service script
Executing: /lib/systemd/systemd-sysv-install enable docker

Step 6: Optional - Add User to Docker Group

Allow running Docker without sudo (security consideration applies).

# Add current user to docker group
sudo usermod -aG docker $USER
 
# Apply group changes (logout/login or use newgrp)
newgrp docker

WARNING

Security Note: Adding users to the docker group grants root-equivalent privileges. Only do this in trusted lab environments.

Validation

Verify your Docker installation with these tests:

Test 1: Docker Service Status

sudo systemctl status docker

Expected Result: Active (running) status with recent startup time

Test 2: Docker Version Check

docker --version
docker compose version

Expected Result:

Docker version 24.0.x, build xxxxx
Docker Compose version v2.20.x

Test 3: Container Test

docker run hello-world

Expected Result:

Hello from Docker!
This message shows that your installation appears to be working correctly.

Test 4: Docker Info

docker info

Expected Result: Detailed system information without errors

Next Steps

  • Related Labs:
  • Advanced Configuration:
    • Docker daemon configuration (/etc/docker/daemon.json)
    • Custom bridge networks and storage drivers
  • Production Considerations:
    • Enable Docker Content Trust
    • Configure logging drivers
    • Set up monitoring with cAdvisor

Common Issues

Issue: “Cannot connect to the Docker daemon socket”

Cause: Docker service not running or user not in docker group Solution:

sudo systemctl start docker
# If using docker group:
newgrp docker

Issue: “Package docker-ce has no installation candidate”

Cause: Docker repository not properly configured Solution: Verify repository addition and run sudo apt update

Issue: Permission denied while trying to connect to Docker daemon

Cause: Running docker commands without sudo and not in docker group Solution: Either use sudo docker or add user to docker group (security implications)

Cleanup (Optional)

To completely remove Docker:

# Stop Docker service
sudo systemctl stop docker
 
# Remove Docker packages
sudo apt purge -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
 
# Remove Docker data (WARNING: This deletes all containers and images)
sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd
 
# Remove repository configuration
sudo rm /etc/apt/sources.list.d/docker.list
sudo rm /etc/apt/keyrings/docker.asc

Lab Resources

Community

HELP

Need Help?

Stuck on this lab? Join the TWN Commons Discord to:

  • Share screenshots of error messages
  • Get troubleshooting assistance for your specific OS
  • Discuss Docker security considerations
  • Help others with similar installation issues

Last verified on 2025-09-07 with Ubuntu 22.04 LTS

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