system-version: add assertioon for stateVersion

1 files changed, 5 insertions, 1 deletions

diff --git a/modules/system/version.nix b/modules/system/version.nix
index 5a6b247..087e8dd 100644
--- a/modules/system/version.nix
+++ b/modules/system/version.nix
@@ -1,10 +1,12 @@
-{ config, lib, pkgs, ... }:
+{ options, config, lib, pkgs, ... }:
 
 with lib;
 
 let
   cfg = config.system;
 
+  defaultStateVersion = options.system.stateVersion.default;
+
   gitCommitId = lib.substring 0 7 (commitIdFromGitRepo gitRepo);
   gitRepo = "${toString pkgs.path}/.git";
   releaseFile = "${toString pkgs.path}/.version";
@@ -72,5 +74,7 @@ in
     system.nixpkgsRevision = mkIf (pathIsDirectory gitRepo) (mkDefault gitCommitId);
     system.nixpkgsVersionSuffix = mkIf (pathIsDirectory gitRepo) (mkDefault (".git." + gitCommitId));
 
+    assertions = [ { assertion = cfg.stateVersion <= defaultStateVersion; message = "system.stateVersion = ${toString cfg.stateVersion}; is not a valid value"; } ];
+
   };
 }