Hi!
Thanks for your feedback. First of all, I've just dropped a new update that will create a subdomain if you specify one on the environment variables that does not exist. That was a cool feature I use a lot on previous Docker images I used with other providers.
I don't know if that solves your problem (I think not), but I will be glad of hearing your issue. I don't know if you want to put a single * or something like that in the field of subdomains to update, instead of writing all down (sub1, sub2, sub3, sub4, sub5).
Regarding IPv4 and IPv6, I'm working on implement IPv6 now, I want that to be part of the next release (within one month), as well as multi-arch images. Definitely, I will try to update both at the same time as you want.
Thanks again!
Edit: and of course, feel free to open an issue to ask for more features or bug fixes you may face!
Yes! I use it and yes, I looked into that package and then realised that it uses DynHost too (I don't believe that all packages and docker images all around the web uses DynHost and not API).
It's on my list to learn how to integrate this method into ddns-scripts package of OpenWRT. But I develop this tools on my free time, so there is a lot to do and no time. But I will look into it.
thanks for your comment!