nixos/zram-generator: init

nixos/modules/module-list.nix

···
   ./services/system/self-deploy.nix
   ./services/system/systembus-notify.nix
   ./services/system/uptimed.nix
+  ./services/system/zram-generator.nix
   ./services/torrent/deluge.nix
   ./services/torrent/flexget.nix
   ./services/torrent/magnetico.nix

nixos/modules/services/system/zram-generator.nix

···
+{ config, lib, pkgs, ... }:
+let
+  cfg = config.services.zram-generator;
+  settingsFormat = pkgs.formats.ini { };
+in
+{
+  meta = {
+    maintainers = with lib.maintainers; [ nickcao ];
+  };
+
+  options.services.zram-generator = {
+    enable = lib.mkEnableOption (lib.mdDoc "Systemd unit generator for zram devices");
+
+    package = lib.mkPackageOptionMD pkgs "zram-generator" { };
+
+    settings = lib.mkOption {
+      type = lib.types.submodule {
+        freeformType = settingsFormat.type;
+      };
+      default = { };
+      description = lib.mdDoc ''
+        Configuration for zram-generator,
+        see https://github.com/systemd/zram-generator for documentation.
+      '';
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    system.requiredKernelConfig = with config.lib.kernelConfig; [
+      (isModule "ZRAM")
+    ];
+
+    # Disabling this for the moment, as it would create and mkswap devices twice,
+    # once in stage 2 boot, and again when the zram-reloader service starts.
+    # boot.kernelModules = [ "zram" ];
+
+    systemd.packages = [ cfg.package ];
+    systemd.services."systemd-zram-setup@".path = [ pkgs.util-linux ]; # for mkswap
+
+    environment.etc."systemd/zram-generator.conf".source = settingsFormat.generate "zram-generator.conf" cfg.settings;
+  };
+}