{ config, pkgs, lib, ... }:
{
systemd.services."nixos-fallback" = {
  after = [ "sshd.service" ];
  #wantedBy = [ "multi-user.target" ];
  serviceConfig = {
    ExecStart = pkgs.writeShellScript "nixos-fallback-start" ''
      set -ux
      # Note that even if switch-to-configuration test
      # restarts nixos-fallback.service,
      # it does not change the system profile.
      profile=/nix/var/nix/profiles/system
      fallback=$(readlink -e /root/nixos-fallback || readlink -e $profile)
      sleep $((10 * 60))
      nix-env --profile $profile --set $fallback
      $fallback/bin/switch-to-configuration switch
      #systemctl reboot
    '';
  };
};
}