modules/drumknotty: split into several parts

This also fixes a few issues, such as enabling `createLocalDatabase` for multiple programs, and wraps all the screen logic within a screenrc file. Some assertions were also added to avoid some easy-to-make mistakes.
2026-03-27 10:07:32 +01:00 · 2026-03-26 16:46:02 +09:00
parent 45a32fad73
commit e64b75f5c5
6 changed files with 551 additions and 400 deletions
--- a/modules/drumknotty/default.nix
+++ b/modules/drumknotty/default.nix
@@ -0,0 +1,198 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  cfg = config.services.drumknotty;
+in
+{
+  imports = [
+    ./dibbler.nix
+    ./worblehat.nix
+  ];
+
+  options.services.drumknotty = {
+    enable = lib.mkEnableOption "DrumknoTTY";
+
+    kioskMode = lib.mkEnableOption "" // {
+      description = ''
+        Whether to let dibbler take over the entire machine.
+
+        This will restrict the machine to a single TTY and make the program unquittable.
+        You can still get access to PTYs via SSH and similar, if enabled.
+      '';
+    };
+
+    screen = {
+      package = lib.mkPackageOption pkgs "screen" { };
+
+      sessionName = lib.mkOption {
+        type = lib.types.str;
+        default = "drumknotty";
+        example = "myscreensessionname";
+        description = ''
+          Sets the screen session name.
+        '';
+      };
+
+      limitHeight = lib.mkOption {
+        type = with lib.types; nullOr ints.unsigned;
+        default = null;
+        example = 42;
+        description = ''
+          If set, limits the height of the screen dibbler uses to the given number of lines.
+        '';
+      };
+
+      limitWidth = lib.mkOption {
+        type = with lib.types; nullOr ints.unsigned;
+        default = null;
+        example = 80;
+        description = ''
+          If set, limits the width of the screen dibbler uses to the given number of columns.
+        '';
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = cfg.enable -> lib.any (b: b) [
+          cfg.dibbler.enable
+          cfg.worblehat.enable
+        ];
+        message = "DrumknoTTY must have at least one service enabled";
+      }
+    ];
+
+    users = {
+      users.drumknotty = {
+        group = "drumknotty";
+        extraGroups = [ "lp" ];
+        isNormalUser = true;
+
+        # TODO: make this display the error log or error message in case that
+        #       the screen session service is bootlooping or otherwise off.
+        shell =
+          lib.mkIf cfg.kioskMode
+          (pkgs.writeShellScriptBin "login-shell"
+            "${lib.getExe' cfg.screen.package "screen"} -x ${cfg.screen.sessionName} -p dibbler"
+          // {
+            shellPath = "/bin/login-shell";
+          });
+      };
+      groups.drumknotty = { };
+    };
+
+    boot.kernelParams = lib.mkIf cfg.kioskMode [
+      "console=tty1"
+    ];
+
+    services.getty.autologinUser = lib.mkIf cfg.kioskMode "drumknotty";
+
+    systemd.services.drumknotty-screen-session = lib.mkIf cfg.kioskMode {
+      description = "Drumknotty Screen Session";
+      wantedBy = [
+        "default.target"
+      ];
+      after =
+        # TODO: this could be refined
+        if (cfg.dibbler.createLocalDatabase || cfg.worblehat.createLocalDatabase) then
+          [
+            "postgresql.service"
+            "dibbler-setup-database.service"
+            "worblehat-setup-database.service"
+          ]
+        else
+          [
+            "network.target"
+          ];
+
+      serviceConfig = {
+        Type = "forking";
+        RemainAfterExit = false;
+        Restart = "always";
+        RestartSec = "5s";
+        SuccessExitStatus = 1;
+
+        User = "drumknotty";
+        Group = "drumknotty";
+
+        ExecStartPre =
+          let
+            screenArgs = lib.escapeShellArgs [
+              # Send the specified command to a running screen session
+              "-X"
+
+              # Session name
+              "-S"
+              "${cfg.screen.sessionName}"
+
+              "kill"
+            ];
+          in
+          "-${lib.getExe' cfg.screen.package "screen"} ${screenArgs}";
+
+        ExecStart =
+          let
+            screenrc = let
+              convertToFile = lines: lib.pipe lines [
+                lib.concatLists
+                (lib.concatStringsSep "\n")
+                (pkgs.writeText "drumknotty-screenrc")
+              ];
+            in convertToFile [
+              (lib.optionals (cfg.screen.limitWidth != null) [
+                "screen width ${toString cfg.screen.limitWidth}"
+              ])
+              (lib.optionals (cfg.screen.limitHeight != null) [
+                "screen height ${toString cfg.screen.limitHeight}"
+              ])
+
+              (let
+                dibblerArgs = lib.cli.toCommandLineShellGNU { } {
+                  config = "/etc/dibbler/dibbler.toml";
+                };
+              in lib.optionals cfg.dibbler.enable [
+                "screen -t worblehat ${lib.getExe cfg.dibbler.package} ${dibblerArgs} loop"
+
+              ])
+
+              (let
+                worblehatArgs = lib.cli.toCommandLineShellGNU { } {
+                  config = "/etc/worblehat/config.toml";
+                };
+              in lib.optionals cfg.worblehat.enable [
+                "screen -t worblehat ${lib.getExe cfg.worblehat.package} ${worblehatArgs} cli"
+              ])
+
+              [ "select 0" ]
+            ];
+
+            screenArgs = lib.escapeShellArgs [
+              # -dm creates the screen in detached mode without accessing it
+              "-dm"
+
+              # Session name
+              "-S"
+              "${cfg.screen.sessionName}"
+
+              # Set optimal output mode instead of VT100 emulation
+              "-O"
+
+              # Enable login mode, updates utmp entries
+              "-l"
+
+              # Config file path
+              "-c"
+              "${screenrc}"
+            ];
+          in
+            "${lib.getExe' cfg.screen.package "screen"} ${screenArgs}";
+      };
+    };
+  };
+}