安装完DOCKER，配置完加速源后，
执行systemctl restart docker后，报错：
Job for docker.service failed because the control process exited with error code. See "systemctl status docker.service" and "journalctl -xe" for details.
查看docker.service状态，执行systemctl status docker.service：
Failed to start Docker Application Container Engine.
解决：
卸载docker：
列出你安装过的包：yum list installed | grep docker
删除安装包：yum -y remove docker-engine.x86_64 docker-client.x86_64 docker-common.x86_64
删除镜像/容器等： rm -rf /var/lib/docker
重新安装：
重新安装docker：yum install docker