nixos-servers/nixos-modules/tailscale.nix

{ lib, config, ... }:
let
  cfg = config.lab.tailscale;
in
{
  options = {
    lab.tailscale.advertiseExitNode = lib.mkOption {
      type = lib.types.bool;
      default = false;
    };
  };

  config = {
    services.tailscale = {
      enable = true;
      authKeyFile = config.sops.secrets."tailscale/authKey".path;
      useRoutingFeatures = "server";
      openFirewall = true;

      extraUpFlags = [
        "--hostname=${config.networking.hostName}"
      ] ++ lib.lists.optional cfg.advertiseExitNode "--advertise-exit-node"
      ++ lib.lists.optional cfg.advertiseExitNode "--advertise-routes=192.168.30.0/24";
    };

    sops.secrets."tailscale/authKey" = { };
  };
}