一 按照阿里云docker镜像配置方法配置docker的镜像，出现如下报错
[root@centos docker]# tee /etc/docker/daemon.json <<-'EOF'
> {
> "registry-mirrors": ["https://48yz3v3v.mirror.aliyuncs.com"]
> }
> EOF
{
"registry-mirrors": ["https://48yz3v3v.mirror.aliyuncs.com"]
}
[root@centos docker]# systemctl daemon-reload
[root@centos docker]# systemctl restart docker
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.这里告诉我们执行 systemctl status docker.service 命令进行排错。
二 排错方法
[root@centos docker]# systemctl status docker
● docker.service - Docker Application Container Engine
Loaded: loaded (/etc/systemd/system/docker.service; enabled; vendor preset: disabled)
Active: failed (Result: start-limit) since Fri 2020-10-09 21:30:04 CST; 1min 11s ago
Docs: https://docs.docker.com
Process: 15511 ExecStart=/usr/bin/dockerd --registry-mirror=https://48yz3v3v.mirror.aliyuncs.com (code=exited, status=1/FAILURE)
Main PID: 15511 (code=exited, status=1/FAILURE)
Oct 09 21:30:04 centos systemd[1]: docker.service: main process exited, code=exited, status=1/FAILURE
Oct 09 21:30:04 centos systemd[1]: Failed to start Docker Application Container Engine.
Oct 09 21:30:04 centos systemd[1]: Unit docker.service entered failed state.
Oct 09 21:30:04 centos systemd[1]: docker.service failed.
Oct 09 21:30:04 centos systemd[1]: docker.service holdoff time over, scheduling restart.
Oct 09 21:30:04 centos systemd[1]: Stopped Docker Application Container Engine.
Oct 09 21:30:04 centos systemd[1]: start request repeated too quickly for docker.service
Oct 09 21:30:04 centos systemd[1]: Failed to start Docker Application Container Engine.
Oct 09 21:30:04 centos systemd[1]: Unit docker.service entered failed state.
Oct 09 21:30:04 centos systemd[1]: docker.service failed.
[root@centos docker]# rm daemon.json
rm: remove regular file ‘daemon.json’? y
[root@centos docker]# systemctl daemon-reload
[root@centos docker]# systemctl restart docker重点关注下面两点：
1 报错文件
/etc/systemd/system/docker.service
2 报错信息
Process: 15511 ExecStart=/usr/bin/dockerd --registry-mirror=https://48yz3v3v.mirror.aliyuncs.com (code=exited, status=1/FAILURE)
三 查看 /etc/systemd/system/docker.service 文件
[root@centos docker]# cat /etc/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target
[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 --registry-mirror=https://48yz3v3v.mirror.aliyuncs.com
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s
[Install]
WantedBy=multi-user.target这里提到了 ExecStart=/usr/bin/dockerd --registry-mirror=https://48yz3v3v.mirror.aliyuncs.com，这句话告诉我们启动后，使用该地址作为镜像加速，其实已经配置了镜像加速。所以无需再配置镜像加速了。
在两个地方都配置镜像加速，系统冲突报错。我们只需配置一个地方即可。