nixos-servers/nixos/physical.nix

{ pkgs, config, lib, modulesPath, microvm, disko, agenix, machines, dns, machine, nixos-hardware, ... }: {
  imports = [
    (modulesPath + "/installer/scan/not-detected.nix")
    microvm.nixosModules.host
    nixos-hardware.nixosModules.raspberry-pi-4
  ];

  config = {

    fileSystems = {
      "/" = {
        device = "/dev/disk/by-label/NIXOS_SD";
        fsType = "ext4";
        options = [ "noatime" ];
      };
    };

    # boot.loader.grub.device = "/dev/sda";
    # boot.loader.grub.enable = true;
    # boot.loader.grub.efiSupport = true;
    # boot.loader.grub.efiInstallAsRemovable = true;
    # boot.loader.grub.device = "nodev";
    # boot = {
    #   # kernelModules = [ "kvm-intel" ];
    #   kernelModules = [ ];
    #   extraModulePackages = [ ];

    #   initrd = {
    #     availableKernelModules = [
    #       "ahci"
    #       "xhci_pci"
    #       "nvme"
    #       "usbhid"
    #       "usb_storage"
    #       "sd_mod"
    #       "sdhci_pci"
    #     ];
    #     kernelModules = [ ];
    #   };

    #   loader = {
    #     # systemd-boot.enable = true;
    #     efi.canTouchEfiVariables = true;
    #   };
    # };

    nixpkgs = {
      config.allowUnfree = true;
      # hostPlatform = machine.arch;
    };

    # hardware.cpu.intel.updateMicrocode = config.hardware.enableRedistributableFirmware;

    age.identityPaths = [ "/etc/age_ed25519" ];

    nix = {
      package = pkgs.nixFlakes;
      extraOptions = ''
        experimental-features = nix-command flakes
      '';
    };

    system = {
      stateVersion = "23.05";

      activationScripts.diff = ''
        if [[ -e  /run/current-system ]]; then
          ${pkgs.nix}/bin/nix store diff-closures /run/current-system "$systemConfig"
        fi
      '';
    };

    microvm.vms =
      let
        vmsForHypervisor = lib.filterAttrs (n: v: v.type == "virtual" && v.hypervisorName == config.networking.hostName) machines;
      in
      builtins.mapAttrs
        (name: vm:
          {
            # Do not restart virtual machines to apply configuration changes.
            # While conceptually this seems useful, it could result in annoying situations.
            # For example, changing the default VM configuration will restart ALL VMs simultaneously, causing a lot of stress on the servers.
            # Downside of not restarting, is that we may need to do this manually now to apply changes.
            restartIfChanged = false;

            specialArgs = {
              inherit agenix disko pkgs lib microvm dns;
              machine = vm;
              hypervisorConfig = config;
            };

            config.imports = [
              ./.
              { networking.hostName = name; }
            ];
          }
        )
        vmsForHypervisor;
  };
}