卸载（如果默认有装Docker）

sudo apt-get remove docker docker-engine docker.io containerd runc

安装Docker

sudo apt-get update
# 安装依赖包
sudo apt-get install apt-transport-https ca-certificates curl gnupg-agent software-properties-common
# 添加 Docker 的官方 GPG 密钥
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
# 验证您现在是否拥有带有指纹的密钥
sudo apt-key fingerprint 0EBFCD88
# 设置稳定版仓库
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

安装 Docker Engine-Community

# 更新
$ sudo apt-get update
# 安装最新的Docker-ce 
sudo apt-get install docker-ce
# 启动
sudo systemctl enable docker
sudo systemctl start docker

测试

sudo docker run hello-world

Ubuntu18.04 安装Docker