Instalar Docker no Ubuntu 18.04

Segue os comandos para instalar o docker:

$ sudo apt update
$ sudo apt install apt-transport-https ca-certificates curl software-properties-common
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable"

$ sudo apt update

$ sudo apt install docker-ce

Se precisar ver o status do serviço:

$ sudo systemctl status docker