Add multi-host configuration

based loosely on https://github.com/tom-on-the-internet/system-configuration

hosts/virtualbox/default.nix

@@ -0,0 +1,12 @@
+{ config, pkgs, ... }:
+
+{
+  imports = [ ./hardware-configuration.nix ];
+
+  boot.loader.grub = {
+    enable = true;
+    device = "/dev/sda";
+  };
+
+  networking.hostName = "virtualbox";
+}

hosts/virtualbox/hardware-configuration.nix

@@ -0,0 +1,30 @@
+# Do not modify this file!  It was generated by ‘nixos-generate-config’
+# and may be overwritten by future invocations.  Please make changes
+# to /etc/nixos/configuration.nix instead.
+{ config, lib, pkgs, modulesPath, ... }:
+
+{
+  imports = [ ];
+
+  boot.initrd.availableKernelModules = [ "ata_piix" "ohci_pci" "sd_mod" "sr_mod" ];
+  boot.initrd.kernelModules = [ ];
+  boot.kernelModules = [ ];
+  boot.extraModulePackages = [ ];
+
+  fileSystems."/" =
+    { device = "/dev/disk/by-label/nixos";
+      fsType = "ext4";
+    };
+
+  swapDevices = [ ];
+
+  # Enables DHCP on each ethernet and wireless interface. In case of scripted networking
+  # (the default) this is the recommended approach. When using systemd-networkd it's
+  # still possible to use this option, but it's recommended to use it in conjunction
+  # with explicit per-interface declarations with `networking.interfaces.<interface>.useDHCP`.
+  networking.useDHCP = lib.mkDefault true;
+  # networking.interfaces.enp0s3.useDHCP = lib.mkDefault true;
+
+  hardware.cpu.intel.updateMicrocode = lib.mkDefault config.hardware.enableRedistributableFirmware;
+  virtualisation.virtualbox.guest.enable = true;
+}

hosts/virtualbox/home.nix

@@ -0,0 +1,3 @@
+{ pkgs, ... }: {
+
+}