snowflake/hosts/sora/services/tailscale.nix

{
  config,
  lib,
  pkgs,
  ...
}:
{
  sops.secrets.tsauth-sora = {
    sopsFile = ../../../secrets/tailscale/secrets.yaml;
  };
  environment.systemPackages = [
    pkgs.jq
    pkgs.tailscale
  ];
  services.tailscale = {
    useRoutingFeatures = lib.mkDefault "server"; # important to make it a server, it sets sysctl for ip forwarding without intervention and reboot
  };
  networking.firewall.allowedUDPPorts = [ config.services.tailscale.port ];
  networking.firewall.trustedInterfaces = [ config.services.tailscale.interfaceName ];

  systemd.services.tailscale-autoconnect = {
    description = "Automatic connection to Tailscale";

    # make sure tailscale is running before trying to connect to tailscale
    after = [
      "network-pre.target"
      "tailscale.service"
    ];
    wants = [
      "network-pre.target"
      "tailscale.service"
    ];
    wantedBy = [ "multi-user.target" ];

    # set this service as a oneshot job
    serviceConfig.Type = "oneshot";

    # have the job run this shell script
    script = with pkgs; ''
      # wait for tailscaled to settle
      sleep 2

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

      # otherwise authenticate with tailscale
      ${tailscale}/bin/tailscale up --authkey file:${config.sops.secrets.tsauth-sora.path} --advertise-exit-node=true --accept-dns=false
    '';
  };
}