os/modules/wireguard/private.nix

{
  lib,
  config,
  pkgs,
  ...
}: let
  cfg = config.pub-solar.wireguard.private;
in {
  options.pub-solar.wireguard.private = {
    ownIPs = lib.mkOption {
      description = ''
        Internal ips in wireguard used for cluster control-plane communication.
      '';
      type = lib.types.listOf lib.types.str;
      default = [];
    };

    privateKeyFile = lib.mkOption {
      description = ''
        Location of private key file
      '';
      type = lib.types.path;
    };

    useDNS = lib.mkOption {
      description = ''
        Whether to use the wireguard DNS
      '';
      default = true;
      type = lib.types.bool;
    };

    fullTunnel = lib.mkOption {
      description = ''
        Whether to tunnel all traffic through the wireguard VPN
      '';
      default = false;
      type = lib.types.bool;
    };
  };

  config = lib.mkIf (builtins.length cfg.ownIPs != 0) {
    networking.firewall.allowedUDPPorts = [51899];

    systemd.network.wait-online.ignoredInterfaces = ["wg-private"];

    systemd.services.wireguard-wg-private = import ./service-override.nix lib;

    networking.wireguard.interfaces = {
      wg-private = {
        listenPort = 51899;
        mtu = 1300;
        ips = cfg.ownIPs;
        privateKeyFile = cfg.privateKeyFile;
        postSetup =
          ""
          + (
            if cfg.useDNS
            then ''
              printf "nameserver 10.13.12.7\nnameserver fd00:b12f:acab:1312:acab:7::" | resolvconf -a wg-private -m 0 -x
            ''
            else ""
          )
          + (
            if cfg.fullTunnel
            then ''
              defaultRoute=$(${pkgs.iproute2}/bin/ip r | ${pkgs.gnugrep}/bin/grep "default via" | head -n 1 | ${pkgs.gawk}/bin/awk '{ print $3 " " $4 " " $5 }')
              ipv4=$(${pkgs.dnsutils}/bin/dig +short A vpn.b12f.io)
              ${pkgs.iproute2}/bin/ip route add $ipv4 metric 256 via $defaultRoute
              ipv6=$(${pkgs.dnsutils}/bin/dig +short AAAA vpn.b12f.io)
              ${pkgs.iproute2}/bin/ip route add $ipv6 metric 256 via $defaultRoute
              ip -4 route delete default dev wg-private || true
              ip -4 route replace default dev wg-private metric 512
              ip -6 route delete default dev wg-private || true
              ip -6 route replace default dev wg-private metric 512
            ''
            else ""
          );
        postShutdown = lib.mkIf cfg.useDNS ''
          resolvconf -d wg-private -f
        '';
        peers = [
          {
            # frikandel
            publicKey = "p6YKNYBlySKfhTN+wbSsKdoNjzko/XSAiTAlCJzP1jA=";
            allowedIPs =
              [
                "10.13.12.0/24"
                "fd00:b12f:acab:1312::/64"
              ]
              ++ (
                if cfg.fullTunnel
                then [
                  "0.0.0.0/0"
                  "::/0"
                ]
                else []
              );
            endpoint = "vpn.b12f.io:51899";
            dynamicEndpointRefreshSeconds = 30;
          }
        ];
      };
    };
  };
}