From c4cfa6e398f44bf965e5d452036ae37e8ec5f471 Mon Sep 17 00:00:00 2001
From: Edgar <39066502+Guekka@users.noreply.github.com>
Date: Mon, 29 Jul 2024 09:09:39 +0200
Subject: [PATCH] Update nixos-server-1.md

#5
---
 content/nixos-server-1.md | 96 +++++++++++++++++----------------------
 1 file changed, 41 insertions(+), 55 deletions(-)

diff --git a/content/nixos-server-1.md b/content/nixos-server-1.md
index 301a670..779aae2 100644
--- a/content/nixos-server-1.md
+++ b/content/nixos-server-1.md
@@ -161,66 +161,52 @@ We've created our volumes, we've configured the system... But I promised we woul
 We're going to use the following script, credit of mt-caret. Do not forget to replace `vda3` with your data partition.
 
 **16/07/23 update**: it was brought to my attention that [postDeviceCommands can cause data loss](https://discourse.nixos.org/t/what-does-impermanence-add-over-built-in-functionality/27939/16).
-While I did not experience any issue, I have updated the script to use a safer alternative.
+While I did not experience any issue, I have updated the script to use a safer alternative. 
+
+**29/07/24 update**: according to Nire Bryce, the updated script did not work. I'm surprised as it seemed to work locally, but I made the change anyway. I appreciate [their help](https://github.com/Guekka/guekka.github.io/issues/5).
 ```nix
   boot.initrd = {
     enable = true;
     supportedFilesystems = [ "btrfs" ];
 
-    systemd.services.restore-root = {
-      description = "Rollback btrfs rootfs";
-      wantedBy = [ "initrd.target" ];
-      requires = [
-        "dev-vda3"
-      ];
-      after = [
-        "dev-vda3"
-        # for luks
-        "systemd-cryptsetup@${config.networking.hostName}.service"
-      ];
-      before = [ "sysroot.mount" ];
-      unitConfig.DefaultDependencies = "no";
-      serviceConfig.Type = "oneshot";
-      script = ''
-        mkdir -p /mnt
-
-        # We first mount the btrfs root to /mnt
-        # so we can manipulate btrfs subvolumes.
-        mount -o subvol=/ /dev/vda3 /mnt
-
-        # While we're tempted to just delete /root and create
-        # a new snapshot from /root-blank, /root is already
-        # populated at this point with a number of subvolumes,
-        # which makes `btrfs subvolume delete` fail.
-        # So, we remove them first.
-        #
-        # /root contains subvolumes:
-        # - /root/var/lib/portables
-        # - /root/var/lib/machines
-        #
-        # I suspect these are related to systemd-nspawn, but
-        # since I don't use it I'm not 100% sure.
-        # Anyhow, deleting these subvolumes hasn't resulted
-        # in any issues so far, except for fairly
-        # benign-looking errors from systemd-tmpfiles.
-        btrfs subvolume list -o /mnt/root |
-        cut -f9 -d' ' |
-        while read subvolume; do
-          echo "deleting /$subvolume subvolume..."
-          btrfs subvolume delete "/mnt/$subvolume"
-        done &&
-        echo "deleting /root subvolume..." &&
-        btrfs subvolume delete /mnt/root
-
-        echo "restoring blank /root subvolume..."
-        btrfs subvolume snapshot /mnt/root-blank /mnt/root
-
-        # Once we're done rolling back to a blank snapshot,
-        # we can unmount /mnt and continue on the boot process.
-        umount /mnt
-      '';
-    };
-  };
+    postResumeCommands = lib.mkAfter ''
+      mkdir -p /mnt
+      # We first mount the btrfs root to /mnt
+      # so we can manipulate btrfs subvolumes.
+      mount -o subvol=/ /dev/vda3 /mnt
+  
+      # While we're tempted to just delete /root and create
+      # a new snapshot from /root-blank, /root is already
+      # populated at this point with a number of subvolumes,
+      # which makes `btrfs subvolume delete` fail.
+      # So, we remove them first.
+      #
+      # /root contains subvolumes:
+      # - /root/var/lib/portables
+      # - /root/var/lib/machines
+      #
+      # I suspect these are related to systemd-nspawn, but
+      # since I don't use it I'm not 100% sure.
+      # Anyhow, deleting these subvolumes hasn't resulted
+      # in any issues so far, except for fairly
+      # benign-looking errors from systemd-tmpfiles.
+      btrfs subvolume list -o /mnt/root |
+      cut -f9 -d' ' |
+      while read subvolume; do
+        echo "deleting /$subvolume subvolume..."
+        btrfs subvolume delete "/mnt/$subvolume"
+      done &&
+      echo "deleting /root subvolume..." &&
+      btrfs subvolume delete /mnt/root
+
+      echo "restoring blank /root subvolume..."
+      btrfs subvolume snapshot /mnt/root-blank /mnt/root
+  
+      # Once we're done rolling back to a blank snapshot,
+      # we can unmount /mnt and continue on the boot process.
+      umount /mnt
+    '';
+ };
 ```
 
 We can then specify the files we want to keep.