删除旧版本

apt-get remove docker docker-engine docker.io
更新软件包
apt-get update
添加https支持
apt-get install apt-transport-https ca-certificates curl gnupg2 software-properties-common
添加GPGkey
curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -
添加Debian的docker源
add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/debian $(lsb_release -cs) stable"
更新
apt-get update
安装
apt-get install docker-ce
来源：https://sunzq.io/2018/05/25/Debian9%E5%AE%89%E8%A3%85Docker/