There currently is a Certbot hook written in Python that handles this behind the scenes, check: https://github.com/joohoi/acme-dns-certbot-joohoi
However, @edspess I see that you are using my test instance of acme-dns for the validation. I’m not planning to take it offline any time soon, but it should be noted that by using this instance (pointing your CNAME records towards it) you are effectively giving me, the domain owner the power to validate certificates for your domains.
Acme-dns was designed to be run as a self hosted service, but you are of course free to use the testing instance as well but I think the issue with the trust chain needs to be acknowledged.