docker: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers).

although I have already set the https_proxy value, but it still do not work, but setting https_proxy in the systemd configuration of docker will do the trick

systemctl edit docker

[Service]
Environment="HTTP_PROXY=http://USER:PASSWD@SERVER:PORT/"
Environment="HTTPS_PROXY=http://USER:PASSWD@SERVER:PORT/"

systemctl daemon-reload
systemctl restart docker

but when I try kubeadm config images pull, it still return timeout as docker pull, even I tried prefix the command with tsocks, I didnot find any problem with the proxy

I didnot try the solution in this link
https://github.com/docker/for-win/issues/1534#issuecomment-559947758
because I work around the problem by using a mirror without the need of a proxy