How To Install Docker Engine on Ubuntu 18.04 LTS – 20.04 LTS – 21.10 LTS – 22.04 LTS

To get started with Docker Engine on Ubuntu, make sure you meet the prerequisites, then install Docker.

OS requirements

To install Docker Engine, you need the 64-bit version of one of these Ubuntu versions:

• Ubuntu Jammy 22.04 (LTS)
• Ubuntu Impish 21.10
• Ubuntu Focal 20.04 (LTS)
• Ubuntu Bionic 18.04 (LTS)

Docker Engine is compatible with x86_64 (or amd64), armhf, arm64, and s390x architectures.

Uninstall Existing Docker Engine

Older versions of Docker went by the names of docker, docker.io, or docker-engine. Uninstall any such older versions before attempting to install a new version:

# Remove existing version of Docker among docker, docker.io, or docker-engine
moalaa@NetDevOps:~$ sudo apt-get remove docker docker-engine docker.io containerd runc

Images, containers, volumes, and networks stored in /var/lib/docker/ aren’t automatically removed when you uninstall Docker.

Install Docker Engine using Docker Repository:

Before you install Docker Engine for the first time on a new host machine, you need to set up the Docker repository. Afterward, you can install and update Docker from the repository.

Set up the repository

• 1) Update the apt package index and install packages to allow apt to use a repository over HTTPS:

# Refresh the repositories
moalaa@NetDevOps:~$ sudo apt-get update

moalaa@NetDevOps:~$ sudo apt-get install \
   ca-certificates \
   curl \
   gnupg \
   lsb-release

• 2) Add Docker’s official GPG key:

moalaa@NetDevOps:~$ sudo mkdir -p /etc/apt/keyrings

moalaa@NetDevOps:~$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

• 3) Use the following command to set up the repository:

moalaa@NetDevOps:~$ 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/null

Install Docker Engine:

• 1) Update the apt package index:

moalaa@NetDevOps:~$ sudo apt-get update

Note: If you received a GPG error when running apt-get update?

moalaa@NetDevOps:~$ sudo chmod a+r /etc/apt/keyrings/docker.gpg

moalaa@NetDevOps:~$ sudo apt-get update

• 2) Install Docker Engine, containerd, and Docker Compose.

# Install most recent version of Docker Engine:
moalaa@NetDevOps:~$ sudo apt-get install docker-ce docker-ce-cli containerd.io docker-compose-plugin

• 3)Now check the status of Docker Engined as shown below.

moalaa@NetDevOps:~$ sudo systemctl status docker
● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enab>
     Active: active (running) since Sun 2022-10-23 23:46:02 U>
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 11748 (dockerd)
      Tasks: 9
     Memory: 36.0M
     CGroup: /system.slice/docker.service
             └─11748 /usr/bin/dockerd -H fd:// --containerd=/>

• 4) In this step, we will verify that the Docker Engine installation is successful by running the hello-world image:
  sudo docker run hello-world

# Run Hello World Image

moalaa@NetDevOps:~$ sudo docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete 
Digest: sha256:18a657d0cc1c7d0678a3fbea8b7eb4918bba25968d3e1b0adebfa71caddbc346
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.
------

This command downloads a test image and runs it in a container. When the container runs, it prints a confirmation message and exits.

Start Docker Rootless

You have now successfully installed and started Docker Engine. The docker user group exists but contains no users, which is why you’re required to use sudo to run Docker commands.

To add your user to the docker group, run below command:

# Add User to Docker group
moalaa@NetDevOps:~$ sudo usermod -aG docker $USER

Log out and log back in so that your group membership is re-evaluated.

On Linux, you can also run the following command to activate the changes to groups:

moalaa@NetDevOps:~$ newgrp docker

Verify that you can run docker commands without sudo.

moalaa@NetDevOps:~$ docker run hello-world

Hello from Docker!
This message shows that your installation appears to be working correctly.

Install Docker Compose ¶

The Docker Compose documentation keeps pushing you to Docker Desktop.

Luckily, we don’t even need to download Docker Compose from GitHub as it actually came included during the installation of Docker Engine. The only thing we need to do is link to the executable and grant execution permissions.

sudo ln -s /usr/libexec/docker/cli-plugins/docker-compose /usr/bin/docker-compose
sudo chmod u+x /usr/bin/docker-compose