Hi, I tried to use the get_ceritificate http <url> tls directive with on_demand.
I am not using a domain but a static IP address.
In my server I found out that in the /ask (from the on_demand config) request I was getting the IP address but in the /certs request I got an empty string in the "server_name" query param.
I found out that the reason for it is that the domain query param in the on-demand TLS ask request comes from this function in certmagic, but in the get_certificate http <url> request in comes directly from the TLS ClientHello packet (here).
I suggest to use the same function (or the same logic) to get the server name also in the get_certificate HTTP handler.

Thank you very much!