Job for docker.service failed. See 'systemctl status docker.service' and 'journalctl -xn' for details.*** 启动报错，下载相关libs***
sudo yum install device-mapper-event-libs
1.查看当前Docker安装状态：
yum list installed | grep docker
2.下载相关libs （不下载可能会出现 Job for docker.service failed. See 'systemctl status docker.service' and 'journalctl -xn' for details.错误）
sudo yum install device-mapper-event-libs
3.下载Docker
sudo yum install -y docker
4.启动Docker
sudo systemctl start docker.service
5.查看Docker 当前状态
sudo systemctl start docker.service
