Install Docker on Ubuntu: A Step-by Step Guide

Learn how to install Docker on Ubuntu in this easy to follow guide for beginners. Just follow the steps and start using Docker in a matter of minutes.

Docker is a platform that packages the application and all its dependencies in the container so that the application works seamlessly. It uses virtualization technology to provide isolated containers for software and tools. They are similar to virtual machines, but containers are more portable, and more resource-friendly.

This article will show you the easiest way to install Docker on Ubuntu and get it running.

For a detailed introduction to the different components of a Docker container, you can check out What is Docker Container: An Introductory Guide for Beginners.

Installing Docker on Ubuntu

Docker is available for installation from the standard Ubuntu repos, but it may not always be the latest version. To ensure we get the latest version, we’ll install Docker from the official Docker repository.

1. Update Packages

First, update the packages index and install the dependencies necessary to add a new HTTPS repository.

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

2. Add the Docker Repo

Next, import the GPG key for the official Docker repository to your system. This is a security feature to ensure that the software you’re installing is authentic.

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

In order to be able to install Docker on your Ubuntu system, you must first add the stable Docker APT repository to it:

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

Finally, update the package database with the Docker packages from the newly added repo:

sudo apt update

3. Install Docker

To install the latest version of Docker on Ubuntu, run the command below. 

sudo apt install docker-ce docker-ce-cli containerd.io

Congratulations! Docker should now be installed, the service started and enabled to start on boot. In addition, you can check the Docker state using:

systemctl is-active docker

active

When a new version of Docker is released, you can just update the packages using the standard apt update procedure.

Enabling Non-root Users to Run Docker Commands

So far, we have successfully installed a Docker on your Ubuntu system.

By default, only root and user with sudo privileges can execute Docker commands. If you attempt to run the docker command without prefixing it with sudo, you’ll get an output like this:

Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.24/containers/json: dial unix /var/run/docker.sock: connect: permission denied

To run Docker commands as a non-root user, you have to add your user to the docker group. To do that, type in:

sudo usermod -aG docker ${USER}

In the command shown above, ${USER} is an environment variable that holds your username. To apply the new group membership, log out and back in.

Conclusion

In this tutorial we’ve shown you how to install Docker on Ubuntu. To learn more about Docker, check out the official Docker documentation.