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Docker is a revolutionary open-source containerization platform that has redefined the way applications are built, tested, and deployed. It enables developers to package an application and its dependencies into a portable container that runs consistently across diverse environments, whether on local development machines, servers, or cloud-based platforms.

This guide provides a comprehensive step-by-step tutorial on how to install Docker on Ubuntu, ensuring you get the latest version for your projects.

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Prerequisites

Before starting the installation, ensure the following:

1. Supported Ubuntu Version: You are using a compatible Ubuntu version, such as Ubuntu 23.10, 22.04, or 20.04.
2. User Privileges: You have a user account with sudo privileges to execute administrative commands.
3. Updated System: Your system’s package index is up-to-date to avoid compatibility issues.

How to Install Docker on Ubuntu

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Step 1: Update Your System

The first step is to update your system. Keeping your system updated ensures that you have the latest security patches and compatibility improvements. Open a terminal and run:

sudo apt update
sudo apt upgrade -y

This command updates the package index and upgrades all outdated packages.

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Step 2: Install Required Dependencies

Docker requires certain dependencies to be installed before proceeding with the installation. Install them using the following command:

sudo apt install -y ca-certificates curl gnupg

These dependencies ensure secure communication with Docker’s repository and the ability to manage cryptographic keys.

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Step 3: Add Docker’s GPG Key

The GPG key verifies the authenticity of the Docker packages. Add the key to your system using these commands:

sudo mkdir -p /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc

This step ensures that the packages you install are trusted and secure.

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Step 4: Add Docker’s Official Repository

To install the latest version of Docker, add its official repository to your system’s APT sources list. Execute the following command:

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list

The command dynamically fetches your Ubuntu codename (e.g., jammy for Ubuntu 22.04) and configures the repository.

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Step 5: Install Docker

After adding Docker’s repository, update your package index again to include it and install Docker:

sudo apt update
sudo apt-get install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

This command installs Docker along with its essential plugins, ensuring you have all the tools needed to work with containers.

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Step 6: Verify Docker Installation

To confirm that Docker was installed successfully and is running, check its status using:

sudo systemctl status docker

The output should indicate that Docker is active and running. Additionally, verify the installed version with:

docker --version

This displays the current Docker version installed on your system.

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Step 7: Enable Non-Root User Access to Docker

By default, only users with sudo privileges can run Docker commands. To allow a non-root user to execute Docker commands, add the user to the Docker group:

sudo usermod -aG docker $USER

Here, $USER is an environment variable representing the current username. If you want to add another user, replace $USER with the username. After executing the command, log out and log back in to apply the changes.

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Step 8: Test Docker Installation

To ensure Docker is working correctly, run a test container:

docker container run hello-world

This command:

1. Downloads the hello-world test image from Docker Hub (if not already available locally).
2. Runs the container, which outputs a "Hello from Docker" message.

If the message appears, your Docker installation is successful.

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Installing a Specific Version of Docker

Sometimes, you may need to install a specific version of Docker. First, list all available versions in Docker’s repository:

sudo apt update
apt list -a docker-ce

Identify the desired version and install it by specifying the version string. For example:

DOCKER_VERSION=5:26.0.0-1~ubuntu.22.04~jammy
sudo apt-get install docker-ce=$DOCKER_VERSION docker-ce-cli=$DOCKER_VERSION containerd.io docker-buildx-plugin docker-compose-plugin

This ensures you’re installing the exact version required for your project.

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Updating Docker

To update Docker to the latest version, use the following commands:

sudo apt update && sudo apt upgrade

If you wish to prevent Docker from being updated automatically, mark it as held back:

sudo apt-mark hold docker-ce

This is useful in environments where maintaining a specific version is critical.

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Uninstalling Docker

If you need to remove Docker, follow these steps. First, stop all running containers and clean up resources:

docker container stop $(docker container ls -aq)
docker system prune -a --volumes

Next, uninstall Docker:

sudo apt-get purge docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
sudo apt autoremove

To completely remove Docker’s files and directories, run:

sudo rm -rf /var/lib/{docker,containerd}

This removes all traces of Docker from your system.

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Conclusion

In this guide, we have provided detailed instructions on how to install Docker on Ubuntu. From setting up Docker’s repository to running your first test container, you now have all the tools to harness Docker’s full potential. Docker’s portability, scalability, and efficiency make it a cornerstone of modern software development and DevOps practices.

For further exploration, visit Docker’s official documentation or engage with its active community forums. If you encounter any challenges during installation, leave a comment or seek assistance from Docker’s robust user community.

By following this guide, you’re ready to leverage the power of Docker to streamline your development and deployment workflows, unlocking new possibilities for innovation and efficiency.