当虚拟机无法连接访问到外网https://registry-1.docker.io/v2，执行docker pull命令会抛出异常，如下：

[root@localhost default]# docker pull debian

Using default tag: latest

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

通过设置代理可以解决：

  • 创建http-proxy.conf文件:


$ mkdir -p /etc/systemd/system/docker.service.d
$ vim /etc/systemd/system/docker.service.d/http-proxy.conf
添加如下内容：
Environment="HTTP_PROXY=http://(host_name):(port_number)/" "HTTPS_PROXY=http://(host_name):(port_number)/"


如果设置格式如下会有 Get https://registry-1.docker.io/v2/: proxyconnect tcp: tls: first record does not look like a TLS 报错



[Service]　　　　
Environment="HTTP_PROXY=http://<allowed_proxy_ipv4_address>:<proxy_port_num>/"
[Service]　　　　
Environment="HTTPS_PROXY=https://<allowed_proxy_ipv4_address>:<proxy_port_num>/"



执行reload命令:  
$ sudo systemctl daemon-reload

重启docker:  
$ sudo systemctl restart docker

查看环境变量值： 
$ systemctl show --property=Environment docker


再次执行



[root@localhost docker.service.d]# docker pull debian
Using default tag: latest
latest: Pulling from library/debian
55cbf04beb70: Pull complete
Digest: sha256:f1f61086ea01a72b30c7287adee8c929e569853de03b7c462a8ac75e0d0224c4
Status: Downloaded newer image for debian:latest