coturn external-ip from DNS?

I have a coturn server running on my NAT, but do not have a static IP address from my ISP. However, I have DDNS set up for all other network services, such that my domain name always points to my current IP address. Given the way coturn's config file works, I would have to script ddclient to rewrite coturn's config file with my current IP address and restart coturn to use the new config each time the address changes. It would be much easier if I could just supply a domain name for coturn to check the A record of in place of external-ip.