How to Install Docker on Ubuntu: A Step-by-Step Guide
Docker is a powerful platform for containerizing applications, enabling developers to package applications with their dependencies for consistent deployment across environments. This guide provides a concise, step-by-step process to install Docker on Ubuntu, focusing on the most reliable method: installing Docker Engine using the official Docker repository. This is ideal for both development and production environments on Ubuntu 20.04, 22.04, or 24.04.
Prerequisites
- Operating System: Ubuntu 20.04, 22.04, or 24.04 (64-bit).
- User Privileges: A user with
sudoprivileges. - System Requirements:
- 64-bit kernel and CPU with virtualization support.
- At least 2GB RAM and 10GB free disk space.
- Internet connection for downloading packages.
- Optional: SSH access if setting up on a remote server.
Step-by-Step Installation
Step 1: Update the System
Ensure your system is up-to-date to avoid package conflicts.
sudo apt-get update
sudo apt-get upgrade -yStep 2: Uninstall Old Docker Versions (If Any)
Remove any older Docker installations to prevent conflicts.
sudo apt-get remove -y docker docker-engine docker.io containerd runcThis won’t delete existing images or containers, as they’re stored separately.
Step 3: Set Up Docker’s APT Repository
Docker’s official repository provides the latest stable version of Docker Engine.
3.1 Install Dependencies
Install required packages for secure repository access.
sudo apt-get install -y ca-certificates curl gnupg lsb-release3.2 Add Docker’s GPG Key
Add Docker’s official GPG key to verify package authenticity.
sudo mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg3.3 Add Docker Repository
Add the Docker repository to your system’s APT sources.
echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/nullStep 4: Install Docker Engine
Update the package index and install Docker Engine, CLI, and related components.
sudo apt-get update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-pluginStep 5: Verify Installation
Check that Docker is installed and running.
- Verify Docker version:
docker --version- Check Docker service status:
sudo systemctl status docker- Ensure Docker starts on boot:
sudo systemctl enable docker
sudo systemctl enable containerd- Run a test container:
sudo docker run hello-worldThis pulls the hello-world image from Docker Hub and runs it, confirming Docker is working. You should see a success message.
Step 6: Manage Docker as a Non-Root User (Optional)
To run Docker commands without sudo, add your user to the docker group.
sudo usermod -aG docker $USERLog out and back in (or run newgrp docker) for the change to take effect. Verify by running:
docker run hello-worldIf it runs without sudo, the configuration is successful.
Step 7: Post-Installation Configuration (Optional)
- Adjust Docker Storage: By default, Docker uses
/var/lib/dockerfor storage. Ensure sufficient disk space or configure a different storage driver if needed (e.g.,overlay2). - Firewall Settings: If using UFW, allow Docker-related ports:
sudo ufw allow 2375/tcp
sudo ufw allow 2376/tcp- Test Docker Compose: Verify Docker Compose installation:
docker compose versionTroubleshooting Common Issues
- Docker Service Not Starting: Check logs with
journalctl -u dockerand ensure containerd is running (sudo systemctl status containerd). - Permission Denied: Ensure your user is in the
dockergroup or usesudo. - Repository Errors: Verify the correct Ubuntu codename in
/etc/apt/sources.list.d/docker.list(e.g.,jammyfor 22.04). - Networking Issues: Check firewall settings or reset Docker networking with
sudo systemctl restart docker.
Alternative Installation Method: Convenience Script
For testing or development environments, Docker provides a convenience script (not recommended for production):
curl -fsSL https://get.docker.com -o get-docker.sh
sudo sh get-docker.shFollow steps 5 and 6 to verify and configure.
Conclusion
You’ve successfully installed Docker Engine on Ubuntu! You can now start pulling images, building containers, or exploring Docker Compose for multi-container applications. For further learning, check the official Docker documentation or Docker Hub for pre-built images.
If you run into issues, consult the Docker community forums or use docker info --format '{{.ServerErrors}}' for diagnostic information. Happy containerizing!
Note: This guide is based on Ubuntu 22.04/24.04 and Docker’s latest stable release as of August 15, 2025. Always verify the latest instructions on the official Docker website.