dotfiles/nixos/tailscale/default.nix

{
  config,
  pkgs,
  inputs,
  ...
}: let
  inherit
    (inputs.nixpkgs-nixos-unstable.legacyPackages."x86_64-linux")
    tailscale
    ;
in {
  environment.systemPackages = [tailscale];
  services.tailscale = {
    enable = true;
    package = tailscale;
  };

  networking.firewall = {
    trustedInterfaces = ["tailscale0"];
    allowedUDPPorts = [config.services.tailscale.port];
  };
  sops.secrets."tailscale-key-${config.networking.hostName}" = {
    sopsFile = ./keys.sops.yaml;
    restartUnits = ["tailscale-auth.service"];
  };
  systemd.services.tailscale-auth = {
    description = "Auth with tailscale";

    after = ["network-pre.target" "tailscale.service"];
    wants = ["network-pre.target" "tailscale.service"];
    wantedBy = ["multi-user.target"];

    serviceConfig.Type = "oneshot";

    script = ''
      sleep 2

      status="$(${tailscale}/bin/tailscale status -json | ${pkgs.jq}/bin/jq -r .BackendState)"
      if [ $status = "Running" ]; then # if so, then do nothing
        echo "already connected"
        exit 0
      fi

      echo "$status, reauthing"
      ${tailscale}/bin/tailscale up --authkey `cat /run/secrets/tailscale-key-${config.networking.hostName}`
    '';
  };
}