ubuntu 16.04 docker 无法启动

报错日志：
Failed to chown socket at step GROUP: No such process
Failed to listen on Docker Socket for the API.
Subject: Unit docker.socket has failed
解决方法：

vim /usr/lib/systemd/system/docker.socket
SocketGroup=root
systemctl list-unit-files | grep docker
systemctl enable docker.service && systemctl enable docker.socket
systemctl daemon-reload
systemctl restart docker