[root@docker ~]# systemctl status docker.service
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
Active: failed (Result: start-limit) since Mon 2019-12-09 17:11:38 CST; 6min ago
Docs: https://docs.docker.com
Main PID: 1183 (code=exited, status=1/FAILURE)
Dec 09 17:11:36 docker systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Dec 09 17:11:36 docker systemd[1]: Failed to start Docker Application Container Engine.
Dec 09 17:11:36 docker systemd[1]: Unit docker.service entered failed state.
Dec 09 17:11:36 docker systemd[1]: docker.service failed.
Dec 09 17:11:38 docker systemd[1]: docker.service holdoff time over, scheduling restart.
Dec 09 17:11:38 docker systemd[1]: Stopped Docker Application Container Engine.
Dec 09 17:11:38 docker systemd[1]: start request repeated too quickly for docker.service
Dec 09 17:11:38 docker systemd[1]: Failed to start Docker Application Container Engine.
Dec 09 17:11:38 docker systemd[1]: Unit docker.service entered failed state.
Dec 09 17:11:38 docker systemd[1]: docker.service failed.
解决方法：
[root@docker ~]# cd /etc/docker/
[root@docker docker]# ls
daemon.json key.json
[root@docker docker]# rm -rf daemon.json
[root@docker docker]# systemctl start docker