os/modules/wireguard-client/default.nix

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

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

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

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

  config = {
    networking.firewall.allowedUDPPorts = [51899];

    systemd.services.wireguard-wg0 = {
      after = [
        "network.target"
        "network-online.target"
        "nss-lookup.target"
      ];

      serviceConfig = {
        Type = mkForce "simple";
        Restart = "on-failure";
        RestartSec = "30";
      };

      environment = {
        WG_ENDPOINT_RESOLUTION_RETRIES = "infinity";
      };
    };

    networking.wireguard.interfaces = {
      wg0 = {
        listenPort = 51899;
        mtu = 1300;
        ips = cfg.ownIPs;
        privateKeyFile = cfg.wireguardPrivateKeyFile;
        postSetup = lib.mkIf cfg.useDNS ''
          printf "nameserver 10.13.12.7\nnameserver fd00:b12f:acab:1312:acab:7::" | resolvconf -a wg0 -m 0 -x
        '';
        postShutdown = lib.mkIf cfg.useDNS ''
          resolvconf -d wg0 -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";
            persistentKeepalive = 25;
          }
        ];
      };
    };
  };
}