Quick Notes: Install Docker CE on Ubuntu 18.04 LTS

$ sudo apt-get update

$ sudo apt-get install \
     apt-transport-https \
     ca-certificates \
     curl \
     gnupg-agent \
     software-properties-common

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

Verify that you now have the key with the fingerprint 9DC8 5822 9FC7 DD38 854A E2D8 8D81 803C 0EBF CD88, by searching for the last 8 characters of the fingerprint.

$ sudo apt-key fingerprint 0EBFCD88

 Setup stable repository: 

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

$ sudo apt-get update

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

Verify that Docker CE is installed correctly by running the hello-world image.

$ sudo docker run hello-world
$ sudo systemctl enable docker 

Reference:

Get Docker CE for Ubuntu