flake.nix

@@ -7,6 +7,23 @@
 
   outputs = { self, nixpkgs }: {
     lib = {
+      # Prepare an update package for the system.
+      mkUpdate = nixos:
+        let
+          config = nixos.config;
+          pkgs = nixpkgs.legacyPackages.x86_64-linux.pkgs;
+        in
+        nixos.pkgs.runCommand "update-${config.system.image.version}"
+          {
+            nativeBuildInputs = with pkgs; [ xz ];
+          } ''
+          mkdir -p $out
+          xz -1 -cz ${config.system.build.uki}/${config.system.boot.loader.ukiFile} \
+            > $out/${config.system.boot.loader.ukiFile}.xz
+          xz -1 -cz ${config.system.build.image}/${config.boot.uki.name}_${config.system.image.version}.store.raw \
+            > $out/${config.boot.uki.name}_${config.system.image.version}.img.xz
+        '';
+
       # Prepare a ready-to-boot disk image.
       mkInstallImage = nixos:
         let
@@ -36,6 +53,7 @@
       default = self.packages.x86_64-linux.patos_image;
 
       patos_image = self.lib.mkInstallImage self.nixosConfigurations.patos;
+      patos_update = self.lib.mkUpdate self.nixosConfigurations.patos;
 
       # A helper script to run the disk images above.
       qemu-efi =

modules/sysupdate.nix

@@ -36,7 +36,7 @@
       "20-store" = {
         Source = {
           MatchPattern = [
-            "store_@v.img.xz"
+            "${config.boot.uki.name}_@v.img.xz"
           ];
           # Path = "https://download.example.com/";
           # Type = "url-file";
@@ -52,7 +52,7 @@
           # Path = "auto";
           Path = "/dev/sda";
 
-          MatchPattern = "store_@v";
+          MatchPattern = "${config.boot.uki.name}_@v";
 
           Type = "partition";
           ReadOnly = "yes";