(towards) lightweight virtual machines with NixOS and systemd-vmspawn

NixOS provides native systemd-nspawn containers which share /nix/store with the host, reducing their disk footprint. NixOS also provides a build-vm option to nixos-rebuild to create a qemu VM capable of running the whole system with a /nix/store shared with the host, which is similarly very disk-space-efficient. today we’re going to make steps towards combining these two workflows to create…