Moved to systemd for initrd, added integration for vmWithDisko

modules/nixos/impermanence.nix

@@ -24,18 +24,32 @@ in
     resetScript = mkOption {
       type = types.lines;
       description = ''
-        Script to run on boot that resets the root partition.
+        Script to run in order to reset the system to a clean state.
       '';
     };
   };
 
   config = mkIf cfg.enable {
+    # Filesystem setup
     fileSystems."/persist".neededForBoot = true;
-    boot.initrd.postResumeCommands = mkAfter cfg.resetScript;
+    # boot.initrd.postResumeCommands = mkAfter cfg.resetScript;
+    # TODO: Reduce dependency on the root filesystem being ZFS?
+    boot.initrd.systemd.services.impermanence-rollback = {
+      description = "Rollback filesystem to clean state.";
+      wantedBy = [ "initrd.target" ];
+      after = [ "zfs-import.target" ];
+      before = [ "sysroot.mount" ];
+      unitConfig.DefaultDependencies = "no";
+      serviceConfig.Type = "oneshot";
+      script = cfg.resetScript;
+    };
 
     # For home-manager persistence
     programs.fuse.userAllowOther = true;
 
+    # For testing purposes with VM
+    virtualisation.vmVariantWithDisko.virtualisation.fileSystems."/persist".neededForBoot = true;
+
     environment.persistence."/persist/system" = {
       enable = true;
       hideMounts = true;