编辑docker配置文件/etc/docker/daemon.json，具体如下：
sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
{
"registry-mirrors": ["https://we7rwaj4.mirror.aliyuncs.com"]
}
EOF
重启docker服务，以便使配置生效:
sudo systemctl daemon-reload
sudo systemctl restart docker
