Azure
image-build-args doesn't support pass-through envvar propagation
in #772, image-build-args was implemented, but the way it is implemented it wasn't clear how to make it work for pass-through envvars. to better explain this, in docker-compose's environment:, one can do either - BUILD_TIME_ARG=build-time-argument-value or simply just - BUILD_TIME_ARG, with the idea that it would be filled in from $BUILD_TIME_ARG from the environment where docker-compose is being called.
as discussed with @bacongobbler, this doesn't seem to be working for filling the envvars from where draft up is being called, thus resulting in a regression from docker-compose.
if draft.toml supported envvar injection, it may be possible to do something like image-build-args = { BUILD_TIME_ARG = "$BUILD_TIME_ARG", HTTP_PROXY = "$HTTP_PROXY" } as a workaround, but this is an implementation detail that is probably better left to the draft project owners to sort out.
Also related to this would be the inclusion of support for loading said env vars from a .env file
