How to Install Docker on Ubuntu 22.04

Docker is an open-source platform that automates the deployment, scaling, and management of applications. It allows you to package applications and their dependencies into a container, which can then be easily deployed on any system. This guide will walk you through the process of installing Docker on Ubuntu 22.04.

Prerequisites

Before we dive into the installation process, make sure that you have the following prerequisites for the process of installing Docker on Ubuntu 22.04.

Ubuntu 22.04

: Docker installation requires a compatible Linux distribution, and this guide is specifically tailored for Ubuntu 22.04.
Sudo Privileges: You need to have sudo (administrator) privileges to install Docker on your system.
Stable Internet Connection: The installation process involves downloading packages from the internet, so ensure your system is connected to a stable network.

Step 1: Update Your System

Before installing Docker, it's a good practice to update your system's package index. This ensures that all packages are up-to-date and helps avoid potential issues during installation.

bash

sudo apt-get update
sudo apt-get upgrade

Step 2: Install Required Packages

Docker requires a few prerequisite packages. These include apt-transport-https, ca-certificates, curl, software-properties-common, and gnupg. Install these packages using the following command:

bash

sudo apt-get install apt-transport-https ca-certificates curl software-properties-common gnupg
Explanation of Required Packages
apt-transport-https: Allows apt to retrieve packages over HTTPS, ensuring the security of the data.
ca-certificates: Provides certificates to ensure secure communication.
curl: A command-line tool to transfer data from or to a server.
software-properties-common: Adds the ability to manage additional repositories.
gnupg: Adds support for encryption and signing of data.

Step 3: Add Docker’s Official GPG Key

To ensure that the packages you download are legitimate, you need to add Docker’s official GPG key to your system. This step is crucial for verifying the authenticity of Docker packages.

bash

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

Step 4: Add Docker’s Official Repository

Now, you need to add Docker’s official repository to your APT sources. This ensures that you are downloading Docker from a trusted source.

bash

echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
Explanation of the Command
dpkg --print-architecture: Retrieves the system architecture (e.g., amd64).
lsb_release -cs: Fetches the Ubuntu codename (e.g., jammy for Ubuntu 22.04).
signed-by: Ensures that the repository is only used if it’s signed by the specified key.

Step 5: Update the Package Index Again

After adding Docker’s official repository, you need to update your package index again to reflect the changes.

bash

sudo apt-get update

Step 6: Install Docker Engine

With everything set up, you can now install Docker Engine, which is the core component of Docker.

bash

sudo apt-get install docker-ce docker-ce-cli containerd.io
Explanation of Docker Components
docker-ce: The Docker Community Edition Engine.
docker-ce-cli: The Docker Command Line Interface (CLI).
containerd.io: A container runtime that manages the entire lifecycle of containers.

Step 7: Verify Docker Installation

Once Docker is installed, you can verify its successful installation by checking the version:

bash

docker --version
You should see an output similar to:

Docker version 20.10.7, build f0df350

This confirms that Docker is successfully installed on your system.

Step 8: Manage Docker as a Non-Root User

By default, Docker requires root privileges to run. However, it’s possible to manage Docker as a non-root user. This step is optional but recommended for convenience and security.

Add Your User to the Docker Group
To run Docker commands without sudo, add your user to the Docker group:

bash

sudo usermod -aG docker ${USER}
Apply Group Changes
To apply the changes, log out and log back in or run the following command:

bash

newgrp docker
Verify Non-Root Access
To check if you can run Docker without sudo, try running the hello-world container:

bash

docker run hello-world
If the container runs successfully, it means you have set up Docker correctly for non-root access.

Step 9: Enable Docker to Start on Boot

To ensure that Docker starts automatically whenever your system boots up, enable Docker’s systemd service:

bash

sudo systemctl enable docker
Checking Docker’s Status
You can also check the status of the Docker service to ensure it’s running:

bash

sudo systemctl status docker
If Docker is running, you should see output indicating that the service is active.

Step 10: Uninstall Docker (If Necessary)

If you ever need to uninstall Docker, you can do so with the following commands:

Remove Docker Packages
bash

sudo apt-get purge docker-ce docker-ce-cli containerd.io
Remove Docker Data
To completely remove Docker and its associated data, including containers, images, volumes, and networks, use the following command:

bash

sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

Conclusion

You have successfully installed Docker on Ubuntu 22.04. Docker is now ready to use, and you can start building and deploying containers on your system. This powerful tool will enable you to create isolated environments for your applications, making development, testing, and deployment much more efficient. Whether you're a developer, system administrator, or DevOps engineer, Docker will prove to be an invaluable addition to your toolkit.