nixos-config/machines/chungus/network-wireguard.nix

{ config, factsGenerator, clanLib, ... }:
{
  networking.firewall.allowedUDPPorts = [ 51820 ];
  clan.core.facts.services.wireguard = factsGenerator.wireguard { name = "wg0"; };
  clan.core.facts.services.wireguard_ip = factsGenerator.public {
    "wireguard.wg0.cidr" = "10.100.0.2/32";
    "wireguard.wg0.ip" = "10.100.0.2";
  };

  # Enable WireGuard
  networking.wg-quick.interfaces = {
    # Hub and Spoke Setup
    # https://www.procustodibus.com/blog/2020/11/wireguard-hub-and-spoke-config/
    wg0 = {
      address = [
        config.clan.core.facts.services.wireguard_ip.public."wireguard.wg0.cidr".value
      ];
      listenPort = 51820; # to match firewall allowedUDPPorts (without this wg uses random port numbers)
      privateKeyFile = config.clan.core.facts.services.wireguard.secret."wireguard.wg0.key".path;
      mtu = 1280;

      peers = [
        {
          publicKey = clanLib.readFact "wireguard.wg0.pub" "orbi";
          allowedIPs = [
            (clanLib.readFact "wireguard.wg0.cidr" "orbi")
          ];
          endpoint = clanLib.readFact "wireguard.wg0.endpoint" "orbi";
          persistentKeepalive = 25;
        }
      ];
    };
  };
}