ubuntu 18.04 docker on ARM

1. sudo apt update
2. sudo apt install apt-transport-https ca-certificates curl software-properties-common
3. curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
4. sudo add-apt-repository "deb [arch=armhf] https://download.docker.com/linux/ubuntu bionic stable"
5. sudo apt update
6. apt-cache policy docker-ce
7. sudo apt install docker-ce