==dns challenge==

Caddyfile:
<pre>
http://o.umine.io:4433/st30t {
    tls {
        dns cloudflare
    }
    root /st30t/
    browse
}

</pre>


https://stackoverflow.com/questions/48306864/caddy-linux-cloudflare-credentials-missing

https://www.cylindric.net/web/caddyserver-and-cloudflare


==Caddyfile guide==
https://caddyserver.com/v1/docs/caddyfile