{
  description = "hacc infra stuff";

  inputs = {
    mattermost-webapp.url = "https://releases.mattermost.com/6.7.2/mattermost-6.7.2-linux-amd64.tar.gz";
    mattermost-webapp.flake = false;
    mattermost-server.url = "github:mattermost/mattermost-server?ref=v6.7.2";
    mattermost-server.flake = false;

    nixpkgs.url = "github:NixOS/nixpkgs?rev=df2bcbbd1c2aa144261cf1b0003c889c075dc693";
    nixpkgs-unstable.url = "github:NixOS/nixpkgs?rev=ae1dc133ea5f1538d035af41e5ddbc2ebcb67b90";
    nix-hexchen.url = "git+https://gitlab.com/hexchen/nixfiles?ref=main";
    nixos-mailserver.url = "git+https://gitlab.com/simple-nixos-mailserver/nixos-mailserver?rev=f535d8123c4761b2ed8138f3d202ea710a334a1d";
  };

  outputs = { self, nixpkgs, nix-hexchen, ... }@inputs:
    let modules = nix-hexchen.nixosModules;
        profiles = nix-hexchen.nixosModules.profiles;
        pkgs = import ./pkgs {
          sources = inputs;
          system = "x86_64-linux";
        };
        # simulate the evalConfig as contained in nix-hexchen/lib/hosts.nix,
        # but compatible with flakes
        evalConfig = extraSpecial: config: nixpkgs.lib.nixosSystem {
          system = "x86_64-linux";
          modules = [
            config
            nix-hexchen.nixosModules.network.nftables
            { nixpkgs.pkgs = pkgs; }
          ];
          specialArgs = {
            inherit modules profiles evalConfig;
            sources = inputs;
          } // extraSpecial;
        };
    in {
      # do this by hand instead of via nix-hexchen/lib/hosts.nix, since that one
      # apparently can't support pkgs depending on flake inputs
      nixosConfigurations.parsons = nixpkgs.lib.nixosSystem {
        system = "x86_64-linux";
        modules = [
          ./hosts/parsons/configuration.nix
          # not used anymore, but other things in nix-hexchen still depend on it
          nix-hexchen.nixosModules.deploy
          { nixpkgs.pkgs = pkgs; }
        ];
        specialArgs = {
          # with a few exceptions, the flake inputs can be used the same
          # as the niv-style (import nix/sources.nix {})
          sources = inputs;
          inherit modules profiles evalConfig;
        };
      };
    };
}