Prerequisites
To follow this tutorial, you will need the following:
One Ubuntu 18.04 server set up by following the Ubuntu 18.04 initial server setup guide, including a sudo non-root user and a firewall.
Installing Docker
The Docker installation package available in the official Ubuntu repository may not be the latest version. To ensure we get the latest version, we’ll install Docker from the official Docker repository. To do that, we’ll add a new package source, add the GPG key from Docker to ensure the downloads are valid, and then install the package.
First, update your existing list of packages:
sudo apt update
Next, install a few prerequisite packages which let apt use packages over HTTPS:
sudo apt install apt-transport-https ca-certificates curl software-properties-common
Then add the GPG key for the official Docker repository to your system:
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
Add the Docker repository to APT sources:
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable"
Next, update the package database with the Docker packages from the newly added repo:
sudo apt update
Make sure you are about to install from the Docker repo instead of the default Ubuntu repo:
apt-cache policy docker-ce
You’ll see output like this, although the version number for Docker may be different: Output of apt-cache policy docker-ce
docker-ce:
Installed: (none)
Candidate: 18.03.1~ce~3-0~ubuntu
Version table:
18.03.1~ce~3-0~ubuntu 500
500 https://download.docker.com/linux/ubuntu bionic/stable amd64 Packages
Notice that docker-ce is not installed, but the candidate for installation is from the Docker repository for Ubuntu 18.04 (bionic). Finally, install Docker:
sudo apt install docker-ce
Docker should now be installed, the daemon started, and the process enabled to start on boot. Check that it’s running:
sudo systemctl status docker
The output should be similar to the following, showing that the service is active and running: Output
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2021-08-09 19:42:32 UTC; 33s ago
Docs: https://docs.docker.com
Main PID: 5231 (dockerd)
Tasks: 7
CGroup: /system.slice/docker.service
└─5231 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock