Earlier quoted context omitted.
You're not wrong, but Docker comes at it from a different angle; Docker expects you to be handing around tagged images, to solve a similar set (but not the same set!) of problems that reproducible builds solve. Ideally, I want _both_ of them: tagged Docker images being sent between environments (with `docker run -e SOME_ENV=testing imagename` for changing the internal config), but reproducible builds in my Dockerfile…
Yes, you can do this. There is a utility "nix-docker" that will convert a Nix configuration file into a BusyBox Docker image (see e.g. http://zef.me/blog/6049/nix-docker )
and it is actually rather cool since you don't rely on any docker command :)