1.connect： Network is unreachable，如果在虚拟机上记得开网关，
https://www.jianshu.com/p/1677468c4501
2.docker安装不全显示failed to start docker.service unit not found，把防火墙关了再重新下载即可
查看防火墙状态
firewall-cmd --state
停止firewall
systemctl stop firewalld.service
禁止firewall开机启动
systemctl disable firewalld.service
重新下载
yum install docker-ce
https://blog.csdn.net/zytmaster/article/details/106170908
