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

当docker  ps出现Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running以下报错时，首先

systemctl  status   docker

查看docker服务的状态如果处于关闭状态则需要启动docker服务

systemctl  start  docker

如果服务是启动状态docker   ps还是报这个错

vim /usr/lib/systemd/system/docker.service
 
 
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target docker.socket firewalld.service containerd.service time-set.target
Wants=network-online.target containerd.service
Requires=docker.socket
 
[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock 
#此处的sock文件有两处确认一下自己的在/run下面还是/container下面
ExecReload=/bin/kill -s HUP $MAINPID

如果路径ok，那就是docker.socket进程没有关掉

 systemctl stop docker.socket   #停掉docker.socket进程
 systemctl stop docker          #同时把docker也停掉

重新启动服务即可