啟動docker報錯Failed to listen on Docker Socket for the API.

1. 啟動時查看日志發現報錯

# journalctl -xe
Failed to listen on Docker Socket for the API.

2. 查找socket這個配置文件，修改如下

# find / -name docker.socket
/etc/systemd/system/sockets.target.wants/docker.socket

# vim docker.socket 
[Unit]
Description=Docker Socket for the API

[Socket]
ListenStream=/var/run/docker.sock
SocketMode=0660
SocketUser=root
SocketGroup=root  # 這里原來是docker改成root即可，保存退出

[Install]
WantedBy=sockets.target

3. 再次重啟docker

# systemctl restart docker && systemctl enable docker
# systemctl status docker
docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
Active: active (running) since Mar 2021-03-25 13:04:49 CST; 4s ago
Docs: https://docs.docker.com
Main PID: 35283 (dockerd)
Tasks: 9
CGroup: /system.slice/docker.service
└─35283 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.033752207+08:00" level=info msg="ClientConn switching balancer to \"pick_first\"" m
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.120893423+08:00" level=warning msg="Your kernel does not support swap memory limit"
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.120928599+08:00" level=warning msg="Your kernel does not support CPU realtime sched
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.121049967+08:00" level=info msg="Loading containers: start."
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.395286964+08:00" level=info msg="Default bridge (docker0) is assigned with an IP ad
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.600646552+08:00" level=info msg="Loading containers: done."
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.640003408+08:00" level=info msg="Docker daemon" commit=8728dd2 graphdriver(s)=overl
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.640101482+08:00" level=info msg="Daemon has completed initialization"
March  25 13:04:49 harbor-https-144 dockerd[35283]: time="2021-03-25T13:04:49.704265015+08:00" level=info msg="API listen on /var/run/docker.sock"
March  25 13:04:49 harbor-https-144 systemd[1]: Started Docker Application Container Engine.