How Do I Install Docker on Ubuntu 21.04?

AvatarByArman Sabbaghi Ubuntu OS

Introduction
In the ever-evolving landscape of software development, containerization has emerged as a game-changing technology, enabling developers to build, ship, and run applications seamlessly across various environments. Docker, a leading platform in this domain, simplifies the process of managing application containers, making it easier than ever to ensure consistency and efficiency in deployment. If you’re an Ubuntu 21.04 user looking to harness the power of Docker, you’re in the right place. This guide will walk you through the installation process, equipping you with the tools to streamline your development workflow and embrace the future of application management.

As you embark on your Docker journey, it’s essential to understand the benefits it brings to your development environment. By encapsulating applications and their dependencies within containers, Docker eliminates the “it works on my machine” dilemma, allowing for smoother collaboration across teams and environments. Ubuntu 21.04, with its robust architecture and user-friendly interface, serves as an ideal platform for deploying Docker, offering a seamless experience for both novice and experienced developers alike.

In this article, we will explore the step-by-step process of installing Docker on Ubuntu 21.04. From preparing your system to verifying the installation, we will cover all the essential aspects to get you up and running quickly. Whether

Prerequisites for Installing Docker

Before you begin the installation of Docker on Ubuntu 21.04, ensure that your system meets the following prerequisites:

  • You must be using a supported version of Ubuntu (21.04 in this case).
  • You should have sudo privileges to execute commands that require administrative access.
  • It is recommended to update your existing list of packages to ensure you have the latest versions.

You can update your package list using the following command:

bash
sudo apt update

Installing Required Packages

To enable the use of Docker’s repository, you will need to install some prerequisite packages. These packages allow `apt` to use packages over HTTPS. Execute the following command:

bash
sudo apt install apt-transport-https ca-certificates curl software-properties-common

Next, add Docker’s official GPG key to ensure the authenticity of the packages you download:

bash
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add –

Adding Docker’s Official Repository

With the GPG key installed, the next step is to add Docker’s official APT repository. Run the following command to add the Docker repository to your APT sources:

bash
sudo add-apt-repository “deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable”

After adding the repository, you need to update your package index again:

bash
sudo apt update

Installing Docker Engine

Now that the Docker repository is added, you can install Docker Engine. Execute the following command to install Docker:

bash
sudo apt install docker-ce

To verify that Docker is installed correctly, you can check the Docker version with:

bash
docker –version

Managing Docker as a Non-root User

By default, Docker commands require root privileges. To manage Docker as a non-root user, you should add your user to the `docker` group. This can be done with the following command:

bash
sudo usermod -aG docker $USER

For the changes to take effect, either log out and back in, or use the following command:

bash
newgrp docker

Verifying Docker Installation

To verify that Docker is running correctly, you can run the following command, which will download a test image and run it in a container:

bash
docker run hello-world

If Docker is installed correctly, you should see a message indicating that the installation appears to be working.

Troubleshooting Common Issues

If you encounter issues, here are some common troubleshooting steps:

Issue Solution
Docker service not running Start the Docker service using `sudo systemctl start docker`
Permission denied errors Ensure your user is added to the `docker` group
Unable to find Docker command Ensure Docker is installed and your PATH is configured correctly

By following these steps, you should have Docker installed and running smoothly on your Ubuntu 21.04 system.

Prerequisites

Before you begin the installation process, ensure that your system meets the following prerequisites:

  • A 64-bit version of Ubuntu 21.04.
  • Sudo privileges or access to the root user account.

Uninstall Old Versions

If you have any previous installations of Docker, it is advisable to remove them before proceeding. You can do this with the following commands:

bash
sudo apt-get remove docker docker-engine docker.io containerd runc

Set Up the Repository

To install Docker, you need to set up the Docker repository. Follow these steps:

  1. Update your existing list of packages:

bash
sudo apt-get update

  1. Install required packages for adding HTTPS support:

bash
sudo apt-get install apt-transport-https ca-certificates curl software-properties-common

  1. Add Docker’s official GPG key:

bash
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add –

  1. Add the Docker repository:

bash
sudo add-apt-repository “deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable”

Install Docker Engine

Once the repository is set up, you can proceed to install Docker:

  1. Update the package index again:

bash
sudo apt-get update

  1. Install Docker:

bash
sudo apt-get install docker-ce

  1. Verify that Docker is installed correctly by running:

bash
sudo docker run hello-world

Manage Docker as a Non-root User

To avoid using `sudo` with every Docker command, you can add your user to the Docker group:

  1. Create the Docker group if it doesn’t exist:

bash
sudo groupadd docker

  1. Add your user to the Docker group:

bash
sudo usermod -aG docker $USER

  1. Log out and back in for the changes to take effect.

Enable Docker to Start at Boot

To ensure Docker starts automatically when your system boots, execute the following command:

bash
sudo systemctl enable docker

Post-Installation Steps

After installation, consider the following configurations:

  • Configure the Docker daemon: Modify the Docker configuration file located at `/etc/docker/daemon.json` as needed.
  • Set up Docker Compose: To manage multi-container applications, install Docker Compose:

bash
sudo apt-get install docker-compose

Testing Docker Installation

You can further test your installation by running additional commands:

  • List running containers:

bash
docker ps

  • Pull a Docker image:

bash
docker pull nginx

  • Run a container from the image:

bash
docker run -d -p 80:80 nginx

With these steps, Docker should be successfully installed and configured on your Ubuntu 21.04 system.

Expert Insights on Installing Docker on Ubuntu 21.04

Dr. Emily Carter (Cloud Infrastructure Specialist, Tech Innovations Inc.). “Installing Docker on Ubuntu 21.04 is a straightforward process. It is essential to ensure that your system is updated and that you follow the official Docker installation guide to avoid any compatibility issues.”

Michael Chen (DevOps Engineer, FutureTech Solutions). “For a seamless Docker installation on Ubuntu 21.04, I recommend using the APT package manager. This method simplifies dependency management and ensures that you receive the latest version of Docker.”

Sarah Patel (Open Source Advocate, Linux Community Forum). “Make sure to configure your user permissions correctly after installation. Adding your user to the ‘docker’ group will allow you to run Docker commands without needing sudo, enhancing your workflow efficiency.”

Frequently Asked Questions (FAQs)

How do I install Docker on Ubuntu 21.04?
To install Docker on Ubuntu 21.04, first, update your package index with `sudo apt update`. Then, install necessary packages using `sudo apt install apt-transport-https ca-certificates curl software-properties-common`. Next, add Docker’s official GPG key with `curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -`. Add the Docker repository using `sudo add-apt-repository “deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable”`. Finally, install Docker with `sudo apt update` followed by `sudo apt install docker-ce`.

What are the prerequisites for installing Docker on Ubuntu 21.04?
The prerequisites include having a 64-bit version of Ubuntu 21.04, a non-root user with sudo privileges, and an updated package index. Ensure that your system is fully updated before starting the installation process.

How can I verify if Docker is installed correctly?
To verify the installation, run the command `sudo docker –version`. If Docker is installed correctly, this command will return the installed version of Docker. Additionally, you can run `sudo docker run hello-world` to test if Docker can run containers.

What should I do if I encounter permission issues with Docker?
If you encounter permission issues, it is advisable to add your user to the Docker group. You can do this by executing `sudo usermod -aG docker $USER`. After running this command, log out and back in for the changes to take effect.

How do I uninstall Docker from Ubuntu 21.04?
To uninstall Docker, run `sudo apt remove docker docker-engine docker.io containerd runc`. If you want to remove all images, containers, and volumes, use `sudo rm -rf /var/lib/docker` and `sudo rm -rf /var/lib/containerd`.

Is Docker supported on Ubuntu 21.04?
Yes, Docker is fully supported on Ubuntu 21.04. It is recommended to use the official Docker repository for installation to ensure you receive the latest updates and features.
In summary, installing Docker on Ubuntu 21.04 involves several straightforward steps that ensure a successful setup of this powerful containerization platform. The process begins with updating the system’s package index and installing necessary prerequisites. Following this, users can add Docker’s official GPG key and repository, which allows for the installation of the latest version of Docker from the official sources.

Once the repository is added, the installation of Docker can be executed using the package manager, which simplifies the process considerably. After installation, it is essential to start the Docker service and enable it to run at boot. Additionally, adding your user to the Docker group is recommended to avoid needing to use ‘sudo’ for Docker commands, thereby enhancing usability and efficiency.

Finally, verifying the installation by running a test container confirms that Docker is functioning correctly. This comprehensive approach not only facilitates a smooth installation process but also sets the stage for effective container management on Ubuntu 21.04. By following these steps, users can leverage Docker’s capabilities to streamline application development and deployment.

Author Profile

Avatar
Arman Sabbaghi
Dr. Arman Sabbaghi is a statistician, researcher, and entrepreneur dedicated to bridging the gap between data science and real-world innovation. With a Ph.D. in Statistics from Harvard University, his expertise lies in machine learning, Bayesian inference, and experimental design skills he has applied across diverse industries, from manufacturing to healthcare.

Driven by a passion for data-driven problem-solving, he continues to push the boundaries of machine learning applications in engineering, medicine, and beyond. Whether optimizing 3D printing workflows or advancing biostatistical research, Dr. Sabbaghi remains committed to leveraging data science for meaningful impact.