{
machine1 = {pkgs, lib, config, options, ...}:
let ipv4 = if options.networking.privateIPv4.isDefined
           then config.networking.privateIPv4
           else "X.X.X.X";
in
{

  config = {
    deployment.targetEnv             = "virtualbox";
    deployment.virtualbox.headless   = true;
    deployment.virtualbox.memorySize = 1024;
    deployment.virtualbox.vcpu       = 2;
    deployment.virtualbox.disks.disk1.baseImage = <sys/var/virtualbox/nixops.vmdk>;
    #deployment.virtualbox.disks.disk1.size = 6024;
     # NOTE: resize not yet supported.

    deployment.storeKeysOnMachine = true;
    deployment.autoLuks = {
      # NOTE: not working on virtualbox deployment
      secretdisk = {
        device     = "/dev/sda";
        passphrase = "foobar";
        autoFormat = true;
        cipher     = "aes-cbc-essiv:sha256";
      };
     };
    networking = {
      interfaces."enp0s8" = {
        #macAddress = "00:11:22:33:44:55";
        ipv4.addresses = [ { address = ipv4; prefixLength = 32; } ];
        ipv6.addresses = [ { address = "fe80::1"; prefixLength = 64; } ];
      };
      zones = {
        net = {
          iface = "enp0s3";
          ipv4  = ipv4;
        };
        lan = {
          iface = "enp0s8";
          ipv4  = ipv4;
          #ipv6  = "fe80::1";
        };
      };
    };
  };
};
}