Some way of diff'ing your system closure before and after applying facter

[brianmcgee]

Perhaps "nix-diff" combined with extendModules can be used to set an empty report?

@r-vdp I heard this is something that you do, is there a pattern you can share?

[r-vdp]

So, what you can do is something like adding this in your config:

{ config, extendModules }: {
    config.system.build.toplevelWithEmptyFacter =
      (extendModules {
        modules =
          let
            prevConfig = config;
          in
          [
            {
              config.facter.report = {
                inherit (prevConfig.facter.report) system;
                hardware.graphics_card = [ ];
              };
            }
          ];
      }).config.system.build.toplevel;
} 

And then nix-diff this with your normal toplevel:

nix run 'nixpkgs#nix-diff' -- (nix build -vL '.#nixosConfigurations.framework.config.system.build.toplevelWithEmptyFacter' --print-out-paths) (nix build -vL '.#nixosConfigurations.framework.config.system.build.toplevel' --print-out-paths)

This works ok, but I'm not sure it captures everything.

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/nixos-facter-moved-to-nix-community/58818/13