1 files changed, 45 insertions, 0 deletions
diff --git a/modules/core/impermanence.nix b/modules/core/impermanence.nix
new file mode 100644
index 0000000..c5f3009
--- /dev/null
+++ b/modules/core/impermanence.nix
@@ -0,0 +1,45 @@
+{ pkgs, lib, ... }:
+
+{
+  boot.initrd.postDeviceCommands = lib.mkAfter ''
+    mkdir /btrfs_tmp
+    mount /dev/root_vg/root /btrfs_tmp
+    if [[ -e /btrfs_tmp/root ]]; then
+        mkdir -p /btrfs_tmp/old_roots
+        timestamp=$(date --date="@$(stat -c %Y /btrfs_tmp/root)" "+%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
+  '';
+
+  fileSystems."/persist".neededForBoot = true;
+  environment.persistence."/persist/system" = {
+    hideMounts = true;
+    directories = [
+      "/etc/nixos"
+      "/var/log"
+      "/var/lib/bluetooth"
+      "/var/lib/nixos"
+      "/var/lib/systemd/coredump"
+      "/etc/NetworkManager/system-connections"
+    ];
+    files = [
+      "/etc/machine-id"
+      { file = "/var/keys/secret_file"; parentDirectory = { mode = "u=rwx,g=,o="; }; }
+    ];
+  };
+}