Hey Albert!
At present there isn't any plan to add that feature, nor would I
or the other devs working on Adjutant likely have the time to
build it.
That said if you have a developer who wants to work on such a
feature, I'd be happy to help work with them to design it so it
fits into what we currently have. The original design was going to
be closer to that (allow customers to ask for a specific quota
changes), but we kept finding that they'd ask for one quota, then
another because they didn't realise they were related. So we opted
for defined sizes as default.
I'm not at all against finding a way to offer both options in a
way that works together. :)
Future plans though do include splitting the quota parts of
Adjutant into their own plugin (and a second horizon plugin) so we
can keep some of that logic out of the core service as well but
maintain it as a 'core' plugin. So this could be a good time to
fit that work in together and deprecate the quota parts in
Adjutant itself for removal later.
Feel free to bug me about anything as you need, and do come say
hello in #openstack-adjutant on freenode!
Cheers,
Adrian