Modularise config. Add sops-nix for secrets management.

configuration/server/vm.nix

@@ -0,0 +1,30 @@
+{ lib, modulesPath, ... }:
+{
+  # Import qemu guest configuration.
+  imports = [
+    (modulesPath + "/profiles/qemu-guest.nix")
+  ];
+
+  # Load kernel modules.
+  boot.initrd.availableKernelModules = [
+    "ata_piix"
+    "uhci_hcd"
+    "virtio_pci"
+    "virtio_scsi"
+    "sd_mod"
+  ];
+
+  boot.kernelModules = [ "kvm-intel" ];
+
+  # Enable DHCP.
+  networking.useDHCP = lib.mkDefault true;
+
+  # Configure the bootloader.
+  boot.loader.grub = {
+    enable = true;
+    device = "/dev/sda";
+  };
+
+  # Enable QEMU guest agent
+  services.qemuGuest.enable = true;
+}