Simplifying

modules/boot.nix

@@ -0,0 +1,34 @@
+{ config, pkgs, lib, ... }:
+
+{
+    boot = {
+        loader = {
+            systemd-boot.enable = true;
+            efi.canTouchEfiVariables = true;
+        };
+        initrd.postDeviceCommands = lib.mkAfter ''
+            mkdir /btrfs_tmp
+            mount /dev/disk/by-label/NIXOS /btrfs_tmp
+            if [[ -e /btrfs_tmp/root ]]; then
+                mkdir -p /btrfs_tmp/old_roots
+                timestamp=$(dat +%Y-%m-%d_%H-%M-%S)
+                mv /btrfs_tmp/root "/btrfs_tmp/old_roots/$timestamp"
+            fi
+
+            delete_subvolume_recursively() {
+                IFS=$'\n'
+                for i in $(btrfs subvolume list -o "$1" | cut -f 9 -d ' '); do
+                    delete_subvolume_recursively "/btrfs_tmp/$i"
+                done
+                btrfs subvolume delete "$1"
+            }
+
+            for i in $(find /btrfs_tmp/old_roots/ -maxdepth 1 -mtime +30); do
+                delete_subvolume_recursively "$i"
+            done
+
+            btrfs subvolume create /btrfs_tmp/root
+            umount /btrfs_tmp
+        '';
+    };
+}