feat(odin): adding impermanence

hosts/odin/default.nix

@@ -5,7 +5,7 @@
     { config.facter.reportPath = ./facter.json; }
 
     outputs.modules.global.nix-config
-    # inputs.impermanence.nixosModules.impermanence
+    inputs.impermanence.nixosModules.impermanence
     inputs.disko.nixosModules.disko
 
     ./disko.nix
@@ -37,50 +37,48 @@
       "vm.swappiness" = 10;
       "net.core.default_qdisc" = "cake";
     };
-  };
 
-  #   # Impermanence: reset root on boot
-  #   initrd.postDeviceCommands = lib.mkAfter ''
-  #     # Get device from disko config
-  #     DEVICE=/dev/disk/by-id/nvme-KINGSTON_SNV3S1000G_50026B7383CC0908-part2
-  #
-  #     mkdir -p /mnt
-  #     mount -o subvol=/ $DEVICE /mnt
-  #
-  #     # Create a directory for old roots if it doesn't exist
-  #     mkdir -p /mnt/old-roots
-  #
-  #     # Move current root to old-roots with timestamp if it exists
-  #     if [[ -e /mnt/@root && ! -e /mnt/@root-blank ]]; then
-  #       timestamp=$(date --date="@$(stat -c %Y /mnt/@root)" "+%Y-%m-%d_%H:%M:%S")
-  #       mv /mnt/@root "/mnt/old-roots/@root-$timestamp"
-  #     fi
-  #
-  #     # Function to recursively delete subvolumes
-  #     delete_subvolume_recursively() {
-  #       for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
-  #         delete_subvolume_recursively "/mnt/$i"
-  #       done
-  #       btrfs subvolume delete "$1"
-  #     }
-  #
-  #     # Delete old roots older than 30 days
-  #     for i in $(find /mnt/old-roots/ -maxdepth 1 -mtime +30); do
-  #       delete_subvolume_recursively "$i"
-  #     done
-  #
-  #     # Create fresh root from blank if needed or create blank if it doesn't exist
-  #     if [[ -e /mnt/@root-blank ]]; then
-  #       btrfs subvolume delete /mnt/@root || true
-  #       btrfs subvolume snapshot /mnt/@root-blank /mnt/@root
-  #     else
-  #       btrfs subvolume create /mnt/@root-blank
-  #       btrfs subvolume create /mnt/@root
-  #     fi
-  #
-  #     umount /mnt
-  #   '';
-  # };
+    # Impermanence: reset root on boot
+    initrd.postDeviceCommands = lib.mkAfter ''
+      DEVICE=${config.disko.devices.disk.main.device}-part2
+
+      mkdir -p /mnt
+      mount -o subvol=/ $DEVICE /mnt
+
+      # Create a directory for old roots if it doesn't exist
+      mkdir -p /mnt/old-roots
+
+      # Move current root to old-roots with timestamp if it exists
+      if [[ -e /mnt/@root && ! -e /mnt/@root-blank ]]; then
+        timestamp=$(date --date="@$(stat -c %Y /mnt/@root)" "+%Y-%m-%d_%H:%M:%S")
+        mv /mnt/@root "/mnt/old-roots/@root-$timestamp"
+      fi
+
+      # Function to recursively delete subvolumes
+      delete_subvolume_recursively() {
+        for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+          delete_subvolume_recursively "/mnt/$i"
+        done
+        btrfs subvolume delete "$1"
+      }
+
+      # Delete old roots older than 30 days
+      for i in $(find /mnt/old-roots/ -maxdepth 1 -mtime +30); do
+        delete_subvolume_recursively "$i"
+      done
+
+      # Create fresh root from blank if needed or create blank if it doesn't exist
+      if [[ -e /mnt/@root-blank ]]; then
+        btrfs subvolume delete /mnt/@root || true
+        btrfs subvolume snapshot /mnt/@root-blank /mnt/@root
+      else
+        btrfs subvolume create /mnt/@root-blank
+        btrfs subvolume create /mnt/@root
+      fi
+
+      umount /mnt
+    '';
+  };
 
   hardware = {
     fancontrol = {
@@ -248,26 +246,27 @@
     };
   };
 
-  # # Persistent directories for impermanence
-  # environment.persistence."/persist" = {
-  #   hideMounts = true;
-  #   directories = [
-  #     "/etc/nixos"
-  #     "/etc/ssh"
-  #     "/var/lib/nixos"
-  #     "/var/lib/systemd"
-  #     "/srv"
-  #   ];
-  #   files = [
-  #     "/etc/machine-id"
-  #   ];
-  #   users.thomas = {
-  #     directories = [
-  #       ".ssh"
-  #       ".config"
-  #     ];
-  #   };
-  # };
+  # Persistent directories for impermanence
+  fileSystems."/persist".neededForBoot = true;
+  environment.persistence."/persist" = {
+    hideMounts = true;
+    directories = [
+      "/etc/nixos"
+      "/etc/ssh"
+      "/var/lib/nixos"
+      "/var/lib/systemd"
+      "/srv"
+    ];
+    files = [
+      "/etc/machine-id"
+    ];
+    users.thomas = {
+      directories = [
+        ".ssh"
+        ".config"
+      ];
+    };
+  };
 
   # System state version
   system.stateVersion = "25.05";