file.nix

installer-test = (nixpkgs.lib.nixosSystem {
    system = "x86_64-linux";
    modules = [
      "${nixpkgs}/nixos/modules/virtualisation/qemu-vm.nix"
      "${nixpkgs}/nixos/modules/profiles/qemu-guest.nix"
      ({
        config,
        lib,
        pkgs,
        ...
      }: rec {
        boot.initrd.availableKernelModules = [ "ata_piix" "uhci_hcd" "virtio_pci" "sr_mod" "virtio_blk" ];
        boot.kernelModules = [ "kvm-intel" ];
        boot.kernelParams = lib.mkIf (! virtualisation.graphics) [
          "console=tty1"
          "console=ttyS0,115200"
        ];

        virtualisation = {
          memorySize = 2048;
          useDefaultFilesystems = false;
          graphics = true;
          # fileSystems."/" = {
          #   device = "/dev/vda1";
          #   fsType = "iso9660";
          # };
          fileSystems."/" = {
            device = "none";
            fsType = "tmpfs";
            options = ["mode=0755"];
          };
          forwardPorts = [
            {
              from = "host";
              host.port = 2222;
              guest.port = 22;
            }
          ];
          qemu = {
            drives = [
              {
                file = "${self.outputs.packages.x86_64-linux.installer}/iso/installer.iso";
                driveExtraOpts = {
                  media = "cdrom";
                  format = "raw";
                  readonly = "on";
                };
              }
            ];
          };
        };
      })
    ];
  })
  .config
  .system
  .build
  .vm;