add-apt-repository docker code example

Example 1: docker install ubuntu

$ sudo apt-get update

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

Example 2: docker ubuntu installation

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