"Tailscale up" auth workaround?

Tailscale user:
I’m trying tailscale on my small personal VPS cluster that runs with Ubuntu 18.04 and Docker. Currently, the command tailscale up requires me to authenticate by opening a URL. I wonder if there is an alternative way to do it automatically?

Have you seen “tailscale up --authkey=…” ?
Help article link

You can authenticate by opening the link from another computer with a browser, or wget/curl the given url first,inspect the html, then again wget/curl the POST/GET link inside the html. it works either way.