Move validate to a different file

flake.nix

@@ -123,6 +123,7 @@
 						(builtins.readFile ./.gitlab-ci-build.yml.in)
 					);
 				cache = pkgs.callPackage (import ./nix/cache.nix) { inherit active distroFile; };
+				validate = pkgs.callPackage (import ./nix/validate.nix) {};
 				cache-restore = pkgs.writeShellApplication {
 					name = "cache-restore";
 					runtimeInputs = with pkgs; [
@@ -161,19 +162,6 @@
 						shellcheck -e SC2239 "''${scripts[@]}"
 					'';
 				};
-				validate = pkgs.writeShellApplication {
-					name = "validate";
-					runtimeInputs = with pkgs; [
-						packer
-					];
-					text = ''
-						shopt -s globstar
-						packer init sources
-						for vars in distros/**/*.pkrvars.hcl; do
-							packer validate -except=upload "-var-file=''${vars}" sources/
-						done
-					'';
-				};
 			};
 
 			# https://numtide.github.io/treefmt/