From 1e70382b81def87bd4d273a6ef504eae754450f2 Mon Sep 17 00:00:00 2001
From: nikstur <nikstur@outlook.com>
Date: Sat, 30 Dec 2023 00:42:54 +0100
Subject: [PATCH] nixos/version: add options to identify images

This is useful when building appliance images that use among other
things partition based A/B updates.
---
 nixos/modules/misc/version.nix | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/nixos/modules/misc/version.nix b/nixos/modules/misc/version.nix
index 45dbf45b3ae7..4b33a2e3151a 100644
--- a/nixos/modules/misc/version.nix
+++ b/nixos/modules/misc/version.nix
@@ -28,6 +28,8 @@ let
     DOCUMENTATION_URL = lib.optionalString (cfg.distroId == "nixos") "https://nixos.org/learn.html";
     SUPPORT_URL = lib.optionalString (cfg.distroId == "nixos") "https://nixos.org/community.html";
     BUG_REPORT_URL = lib.optionalString (cfg.distroId == "nixos") "https://github.com/NixOS/nixpkgs/issues";
+    IMAGE_ID = lib.optionalString (config.system.image.id != null) config.system.image.id;
+    IMAGE_VERSION = lib.optionalString (config.system.image.version != null) config.system.image.version;
   } // lib.optionalAttrs (cfg.variant_id != null) {
     VARIANT_ID = cfg.variant_id;
   };
@@ -110,6 +112,38 @@ in
       example = "installer";
     };
 
+    image = {
+
+      id = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = lib.mdDoc ''
+          Image identifier.
+
+          This corresponds to the IMAGE_ID field in os-release. See the
+          upstream docs for more details on valid characters for this field:
+          https://www.freedesktop.org/software/systemd/man/latest/os-release.html#IMAGE_ID=
+
+          You would only want to set this option if you're build NixOS appliance images.
+        '';
+      };
+
+      version = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = null;
+        description = lib.mdDoc ''
+          Image version.
+
+          This corresponds to the IMAGE_VERSION field in os-release. See the
+          upstream docs for more details on valid characters for this field:
+          https://www.freedesktop.org/software/systemd/man/latest/os-release.html#IMAGE_VERSION=
+
+          You would only want to set this option if you're build NixOS appliance images.
+        '';
+      };
+
+    };
+
     stateVersion = mkOption {
       type = types.str;
       # TODO Remove this and drop the default of the option so people are forced to set it.