Is the docker daemon running?

原文

刚在新的Centos上安装Docker-CE,后运行docker run hello-world报错Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

解决办法
$ systemctl daemon-reload
$ sudo service docker restart
$ sudo service docker status (should see active (running))
$ sudo docker run hello-world

docker 客户端经过unix:///var/run/docker.sock与docker daemon通讯，unix:///var/run/docker.sock须要管理员权限才能访问，因此要么运行sudo docker run hello-world，要么将当前用户添加在docker用户组中
sudo usermod -aG docker $USER