Failed to start Docker Application Container Engine.

[root@dockertest ~]# 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 Sat 2019-05-04 19:56:57 CST; 4s ago
Docs: https://docs.docker.com
Process: 13092 ExecStart=/usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock (code=exited, status=1/FAILURE)
Main PID: 13092 (code=exited, status=1/FAILURE)

May 04 19:56:55 dockertest systemd[1]: Failed to start Docker Application Container Engine.
May 04 19:56:55 dockertest systemd[1]: Unit docker.service entered failed state.
May 04 19:56:55 dockertest systemd[1]: docker.service failed.
May 04 19:56:57 dockertest systemd[1]: docker.service holdoff time over, scheduling restart.
May 04 19:56:57 dockertest systemd[1]: Stopped Docker Application Container Engine.
May 04 19:56:57 dockertest systemd[1]: start request repeated too quickly for docker.service
May 04 19:56:57 dockertest systemd[1]: Failed to start Docker Application Container Engine.
May 04 19:56:57 dockertest systemd[1]: Unit docker.service entered failed state.
May 04 19:56:57 dockertest systemd[1]: docker.service failed.

解决办法： //就是删除这个文件就好了，

[root@dockertest /]# cd /etc/docker
[root@dockertest docker]# ls
certs.d daemon.json daemon.json.rpmnew seccomp.json
[root@dockertest docker]# rm daemon.json
rm: remove regular file ‘daemon.json’? y
[root@dockertest docker]# ll
total 16
drwxr-xr-x. 5 root root 75 May 4 20:40 certs.d
-rw-r--r--. 1 root root 3 May 1 22:52 daemon.json.rpmnew
-rw-r--r--. 1 root root 10837 May 1 22:52 seccomp.json
[root@dockertest docker]# systemctl start docker
[root@dockertest docker]# systemctl enable docker

[root@dockertest docker]# systemctl status docker
● docker.service - Docker Application Container Engine
Loaded: loaded (/usr/lib/systemd/system/docker.service; enabled; vendor preset: disabled)
Active: active (running) since Sat 2019-05-04 21:00:23 CST; 1min 16s ago
Docs: http://docs.docker.com
Main PID: 83247 (dockerd-current)
CGroup: /system.slice/docker.service
├─83247 /usr/bin/dockerd-current --add-runtime docker-runc=/usr/libexec/docker/docker-runc-current --default-runtime=docker-runc --exec-opt native.cgroupdri...
└─83255 /usr/bin/docker-containerd-current -l unix:///var/run/docker/libcontainerd/docker-containerd.sock --metrics-interval=0 --start-timeout 2m --state-di...

May 04 21:00:21 dockertest dockerd-current[83247]: time="2019-05-04T21:00:21.945869452+08:00" level=info msg="libcontainerd: new containerd process, pid: 83255"
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.057214144+08:00" level=info msg="Graph migration to content-addressability took 0.00 seconds"
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.058452705+08:00" level=info msg="Loading containers: start."
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.104400849+08:00" level=info msg="Firewalld running: true"
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.385892651+08:00" level=info msg="Default bridge (docker0) is assigned with an IP ... address"
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.632043070+08:00" level=info msg="Loading containers: done."
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.691412948+08:00" level=info msg="Daemon has completed initialization"
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.691454541+08:00" level=info msg="Docker daemon" commit="b2f74b2/1.13.1" graphdriv...on=1.13.1
May 04 21:00:23 dockertest dockerd-current[83247]: time="2019-05-04T21:00:23.746297646+08:00" level=info msg="API listen on /var/run/docker.sock"
May 04 21:00:23 dockertest systemd[1]: Started Docker Application Container Engine.
Hint: Some lines were ellipsized, use -l to show in full.