https://docs.docker.com/engine/admin/systemd/
mkdir /etc/systemd/system/docker.service.d
/etc/systemd/system/docker.service.d/http-proxy.conf
[Service] Environment="HTTP_PROXY=http://192.168.56.1:3128/" "HTTPS_PROXY=http://192.168.56.1:3128/" "NO_PROXY=localhost,127.0.0.0/8"
systemctl daemon-reload
systemctl show --property=Environment docker
systemctl restart docker