add impermanence

hosts/canopus/default.nix

@@ -1,14 +1,16 @@
 {
   inputs,
   pkgs,
+  lib,
   ...
 }: {
   imports = [
     inputs.nixos-hardware.nixosModules.asus-zephyrus-ga503
     inputs.disko.nixosModules.default
-    (import ./disko.nix {device = "/dev/nvme0n1";})
 
+    (import ./disko.nix {device = "/dev/nvme0n1";})
     ./hardware-configuration.nix
+
     ../common
     ../../modules/nixos/desktop
     ../../modules/nixos/desktop/awesome
@@ -46,7 +48,43 @@
   boot = {
     kernelPackages = pkgs.linuxPackages_zen;
     supportedFilesystems = ["ntfs"];
-    initrd.systemd.enable = true;
+
+    initrd.systemd = {
+      enable = lib.mkForce true;
+
+      services.wipe-my-fs = {
+        wantedBy = ["initrd.target"];
+        after = ["initrd-root-device.target"];
+        before = ["sysroot.mount"];
+        unitConfig.DefaultDependencies = "no";
+        serviceConfig.Type = "oneshot";
+        script = ''
+          mkdir /btrfs_tmp
+          mount /dev/disk/by-partlabel/disk-primary-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
+        '';
+      };
+    };
 
     loader = {
       systemd-boot = {
@@ -213,5 +251,24 @@
 
   fonts.packages = with pkgs; [(nerdfonts.override {fonts = ["FiraCode" "JetBrainsMono"];})];
 
+  programs.fuse.userAllowOther = true;
+  fileSystems."/persist".neededForBoot = true;
+  environment.persistence."/persist" = {
+    hideMounts = true;
+    directories = [
+      "/var/log"
+      "/var/lib/tailscale"
+      "/var/lib/nixos"
+      "/etc/NetworkManager/system-connections"
+    ];
+    files = [
+      "/etc/machine-id"
+      "/etc/ssh/ssh_host_ed25519_key"
+      "/etc/ssh/ssh_host_ed25519_key.pub"
+      "/etc/ssh/ssh_host_rsa_key"
+      "/etc/ssh/ssh_host_rsa_key.pub"
+    ];
+  };
+
   system.stateVersion = "24.11";
 }