Nixorium – NixOS for a school computer lab where only the controller has Internet

I teach at a high school in Italy, and manage a few computer labs with about 30 PCs each. Our PCs can’t access the Internet until someone logs into the school network, which made installing and updating them a pain. Two years ago I switched the labs to NixOS and started building tools to deal with it. That’s how Nixorium started. Now only one machine (the controller) needs Internet. It builds and signs the systems, serves them from a local Harmonia cache, and installs clients over PXE or USB...