Any new app on runcloud uses a combination of Apache and NGINX, don't ask me how I know this, it just works like that.
Normally we use
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
In the .htaccess.
Because runcloud have different config, we use
RewriteEngine On
RewriteCond %{HTTP:X-Forwarded-Proto} !https
RewriteRule ^(.*)$ https://%{SERVER_NAME}/$1 [R,L]
