Create NixOS module

flake.nix

@@ -19,5 +19,11 @@
         oh-importer = pkgs.callPackage ./package.nix {};
         default = oh-importer;
       };
-    });
+    })
+    // {
+      nixosModules = rec {
+        oh-importer = import ./module.nix self;
+        default = oh-importer;
+      };
+    };
 }

module.nix

@@ -0,0 +1,51 @@
+self: {
+  config,
+  pkgs,
+  lib,
+  system,
+  ...
+}: let
+  cfg = config.programs.oh-importer;
+
+  appConfig = (pkgs.formats.yaml {}).generate "oh-importer.config.yaml" cfg.config;
+
+  app = pkgs.writeShellApplication {
+    name = "oh-import";
+    runtimeInputs = [self.packages.${system}.default];
+    text = ''
+      oh-import -c "${appConfig}" "$@";
+    '';
+  };
+in
+  with lib; {
+    options.programs.oh-importer = {
+      enable = mkEnableOption "oh-importer";
+
+      config = mkOption {
+        type = types.attrs;
+        description = "The oh-importer config which will be eventually converted to yaml";
+        example = {
+          openHAB = {
+            baseURL = "https://hab.lan";
+            token = "$__file:/run/openhab.token.key";
+          };
+
+          sources = {
+            zigbee = {
+              type = "zigbee2mqtt";
+              config = {
+                brokerURL = "mqtt://mqtt.lan";
+                username = "mqtt-username";
+                password = "$__file:/run/mqtt.password.key";
+                bridgeID = "main";
+                prefix = "zigbee";
+                idTransform = "snake-case";
+              };
+            };
+          };
+        };
+      };
+    };
+
+    config.environment.systemPackages = mkIf cfg.enable [app];
+  }