Install docker on debian stretch [9]

 # apt-get install apt-transport-https ca-certificates curl gnupg2 software-properties-common
 # curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
 # add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"
 # apt-get update
 # apt-cache policy docker-ce
 # apt-get install docker-ce