Add murk and impermanence

modules/nixos/core/boot.nix

@@ -11,10 +11,11 @@
       timeout = 2;
       efi.canTouchEfiVariables = true;
       grub = {
-        enable = true;
+        enable = lib.mkDefault true;
         zfsSupport = true;
         efiSupport = true;
         device = "nodev";
+      } // lib.optionalAttrs (config.mods.monitors != { }) {
         gfxmodeEfi = config.mods.monitors.primary.config.mode;
       };
     };

modules/nixos/default.nix

@@ -7,6 +7,8 @@
     ./server
     ./sops
 
+    ./impermanence.nix
+
     # </3
     ./unfree
   ];

modules/nixos/impermanence.nix

@@ -0,0 +1,41 @@
+{ pkgs, lib, config, ... }:
+with lib; {
+  options.mods.impermanence.enable = mkEnableOption "enables impermanence";
+
+  config = mkIf config.mods.impermanence.enable {
+    environment.persistence."/persistent" = {
+      directories = [
+        "/var/lib/bluetooth"
+        "/var/lib/nixos"
+        "/var/lib/systemd/coredump"
+        "/etc/NetworkManager/system-connections"
+      ];
+      files = [ "/etc/machine-id" ];
+    };
+
+    boot.initrd.postResumeCommands = lib.mkAfter ''
+      mkdir /btrfs_tmp
+      mount /dev/mapper/crypted /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
+    '';
+  };
+}