Unfree packages

Which unfree packages are allowed is configured at the flake level via an option. That is then used in the configuration of Nixpkgs. See definition at unfree-packages.nix. See usage at vscode. The value of this option is available as a flake output:

$ nix eval .#meta.nixpkgs.allowedUnfreePackages

Hosts

The set of NixOS hosts is defined via an option which accepts deferred modules. Differentiating the hosts as a subset of the NixOS modules allows us to map over the hosts both when generating NixOS configurations and when defining checks for the flake.

See definition at hosts.nix. See usage at autolycus.