Centos7 dockers下载镜像报错: Get https://registry-1.docker.io/v2/: net/http: request canceled

docker: Error response from daemon: Get https://registry-1.docker.io/v2/: net/http: request canceled (Client.Timeout exceeded while awaiting headers).

解决方案：
1）创建daemon.json文件
vim /etc/docker/daemon.json
2) 写入：

{
    "registry-mirrors":["https://docker.mirrors.ustc.edu.cn"]
}

3）重启：

[root@km docker]# systemctl daemon-reload 
[root@km docker]# systemctl restart docker

4）问题解决。