{
  description = "personal NixOS configurations";

  inputs = {
    # Nixpkgs, NixOS's official repo
    nixpkgs.url = "github:nixos/nixpkgs/release-21.11";

    utils.url = "github:numtide/flake-utils";

    # We use the unstable nixpkgs repo for some packages.
    nixpkgs-unstable.url = "github:nixos/nixpkgs/nixpkgs-unstable";

    emacs-overlay.url = "github:nix-community/emacs-overlay";

    agenix = {
      url = "github:ryantm/agenix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    nur.url = "github:nix-community/NUR";

    home-manager = {
      url = "github:nix-community/home-manager/release-21.11";
      # We want home-manager to use the same set of nixpkgs as our system.
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  # Output config, or config for NixOS system
  outputs = { ... }@inputs:
    let lib = import ./lib { inherit inputs; };
    in {
      nixosConfigurations = {
        carmel = lib.mkSystem {
          hostname = "carmel";
          system = "x86_64-linux";
        };
        aptos = lib.mkSystem {
          hostname = "aptos";
          system = "x86_64-linux";
        };
        tahoe = lib.mkSystem {
          hostname = "tahoe";
          system = "x86_64-linux";
        };
      };

      homeConfigurations = {
        "fcuny@carmel" = lib.mkHome {
          username = "fcuny";
          system = "x86_64-linux";
          hostname = "carmel";
          isDesktop = true;
        };
        "fcuny@aptos" = lib.mkHome {
          username = "fcuny";
          system = "x86_64-linux";
          hostname = "aptos";
          isDesktop = true;
        };
        "fcuny@tahoe" = lib.mkHome {
          username = "fcuny";
          system = "x86_64-linux";
          hostname = "tahoe";
        };
      };
    } // inputs.utils.lib.eachDefaultSystem (system:
      let
        pkgs = import inputs.nixpkgs { inherit system; };
        home-manager = inputs.home-manager.defaultPackage."${system}";
      in {
        packages = pkgs // { inherit home-manager; };

        devShell = pkgs.mkShell {
          buildInputs = with pkgs; [
            nixUnstable
            nixfmt
            rnix-lsp
            home-manager
            git
          ];
        };
      });
}