puppy-tracker/module.nix

self: { config, lib, pkgs, ... }:

let
  cfg = config.services.puppy-tracker;
  staticPkg = self.packages.${pkgs.system}.static;
  serverPkg = self.packages.${pkgs.system}.server;
in
{
  options.services.puppy-tracker = {
    enable = lib.mkEnableOption "Puppy Tracker (offline-first puppy tracking app with sync server)";

    address = lib.mkOption {
      type = lib.types.str;
      default = "0.0.0.0";
      description = "Address the server listens on.";
    };

    port = lib.mkOption {
      type = lib.types.port;
      default = 8080;
      description = "TCP port the server listens on.";
    };

    openFirewall = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = "Whether to open the configured port in the firewall.";
    };

    inviteCodeFile = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      example = "/run/secrets/puppy-invite-code";
      description = ''
        Path to an EnvironmentFile containing the shared registration secret as
        `PUPPY_INVITE_CODE=...`. Kept out of the Nix store so the code stays
        secret. When null, registration is disabled (existing accounts can still
        log in).
      '';
    };

    vapidKeyFile = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      example = "/run/secrets/puppy-vapid-key";
      description = ''
        Path to an EnvironmentFile containing the Web Push signing key as
        `PUPPY_VAPID_KEY=...` (a base64url P-256 private scalar). When null the
        server generates one on first start and keeps it in its state directory,
        which is fine for a single host. Note that browsers pin this key when
        they subscribe: replacing it silently breaks every existing reminder
        subscription until each device re-enables notifications.
      '';
    };

    secureCookies = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = ''
        Mark session cookies Secure. Enable once the service is reached over
        HTTPS (e.g. behind a TLS-terminating reverse proxy); leave off for plain
        HTTP on a LAN, or browsers will drop the cookie and logins won't stick.
      '';
    };

    package = lib.mkOption {
      type = lib.types.package;
      default = serverPkg;
      defaultText = lib.literalExpression "puppy-tracker.packages.\${system}.server";
      description = "The puppy-tracker server package.";
    };

    staticPackage = lib.mkOption {
      type = lib.types.package;
      default = staticPkg;
      defaultText = lib.literalExpression "puppy-tracker.packages.\${system}.static";
      description = "The puppy-tracker static-site package (HTML/CSS/JS).";
    };
  };

  config = lib.mkIf cfg.enable {
    systemd.services.puppy-tracker = {
      description = "Puppy Tracker server";
      wantedBy = [ "multi-user.target" ];
      after = [ "network.target" ];

      serviceConfig = {
        ExecStart = lib.concatStringsSep " " ([
          "${cfg.package}/bin/puppy-tracker-server"
          "-addr ${cfg.address}:${toString cfg.port}"
          "-static ${cfg.staticPackage}/share/puppy-tracker"
          "-data /var/lib/puppy-tracker/puppy.db"
        ] ++ lib.optional cfg.secureCookies "-secure-cookies");

        # Secrets (registration code, Web Push key) are read from env files kept
        # out of the store, exposed to the server as PUPPY_INVITE_CODE and
        # PUPPY_VAPID_KEY.
        EnvironmentFile = lib.filter (f: f != null) [ cfg.inviteCodeFile cfg.vapidKeyFile ];

        DynamicUser = true;
        StateDirectory = "puppy-tracker";
        StateDirectoryMode = "0750";
        Restart = "on-failure";
        RestartSec = "2s";

        # Hardening
        ProtectSystem = "strict";
        ProtectHome = true;
        PrivateTmp = true;
        PrivateDevices = true;
        NoNewPrivileges = true;
        ProtectKernelTunables = true;
        ProtectKernelModules = true;
        ProtectKernelLogs = true;
        ProtectControlGroups = true;
        RestrictSUIDSGID = true;
        RestrictRealtime = true;
        LockPersonality = true;
        MemoryDenyWriteExecute = true;
        SystemCallArchitectures = "native";
        SystemCallFilter = [ "@system-service" "~@privileged @resources" ];
        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
      };
    };

    networking.firewall.allowedTCPPorts = lib.mkIf cfg.openFirewall [ cfg.port ];
  };
}