{
  description = "Felixalb System flake";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05-small";
    unstable.url = "github:NixOS/nixpkgs/nixos-unstable-small";

    sops-nix.url = "github:Mic92/sops-nix";
    sops-nix.inputs.nixpkgs.follows = "nixpkgs";
  };

  outputs = { self, nixpkgs, unstable, sops-nix, ... }@inputs:
    let
      system = "x86_64-linux";
      overlay-unstable = final: prev: {
        unstable = unstable.legacyPackages.${prev.system};
      };
    in
    {
      nixosConfigurations = {
        voyager = nixpkgs.lib.nixosSystem {
          inherit system;
          specialArgs = {
            inherit inputs;
          };
          modules = [
            # Overlays-module makes "pkgs.unstable" available in configuration.nix
            ({ config, pkgs, ... }: { nixpkgs.overlays = [ overlay-unstable ]; })

            ./hosts/voyager/configuration.nix
            sops-nix.nixosModules.sops
          ];
        };
        chapel = nixpkgs.lib.nixosSystem {
          inherit system;
          specialArgs = {
            inherit inputs;
          };
          modules = [
            ./hosts/chapel/configuration.nix
            sops-nix.nixosModules.sops
          ];
        };
        redshirt = nixpkgs.lib.nixosSystem {
          inherit system;
          specialArgs = {
            inherit inputs;
          };
          modules = [
            ./hosts/redshirt/configuration.nix
            ({ config, pkgs, ... }: { nixpkgs.overlays = [ overlay-unstable ]; })
            sops-nix.nixosModules.sops
          ];
        };
      };

      devShells.x86_64-linux = {
        default = nixpkgs.legacyPackages.x86_64-linux.callPackage ./shell.nix { };
      };
    };
}