docker Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon runn

Reference:
1. https://stackoverflow.com/questions/37227349/unable-to-start-docker-service-in-ubuntu-16-04
2. http://blog.csdn.net/qq_36763896/article/details/53268085

Program:

Process: 8913 ExecStart=/usr/bin/docker daemon -H fd:// -s overlay (code=exited, status=1/FAILURE)

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Do:
open /etc/systemd/system and remove docker.service.d folder

(因为先前配置了Docker Daemon用OverlayFS启动

sudo mkdir -p /etc/systemd/system/docker.service.d

sudo cat >/etc/systemd/system/docker.service.d/override.conf <

sudo systemctl daemon-reloadsystemctl show --property=ExexStart dockersudo systemctl restart docker

finally this problem is solved.