nixos-anywhere-example/template/iso.nix

# This module defines a small NixOS installation CD.  It does not
# contain any graphical stuff.
# https://nixos.wiki/wiki/Creating_a_NixOS_live_CD
{ config, pkgs, ... }:
{
  imports = [
    <nixpkgs/nixos/modules/installer/cd-dvd/installation-cd-minimal.nix>
  ];

  # Enable SSH in the boot process.
  systemd.services.sshd.wantedBy = pkgs.lib.mkForce [ "multi-user.target" ];
  users.users.root.openssh.authorizedKeys.keys = [
    (builtins.readFile ./nitrokey.pub)
  ];
}