sys: implement primitive impermanence

1 files changed, 17 insertions, 4 deletions

diff --git a/sys/fs/default.nix b/sys/fs/default.nix
index 9f2f646..d24e357 100644
--- a/sys/fs/default.nix
+++ b/sys/fs/default.nix
@@ -1,19 +1,32 @@
 { lib, config, ... }:
 with lib; let
-  cfg = config.local;
+  cfg = config.local.fs;
 in {
   imports = [ ./btrfs.nix ./layout.nix ];
 
-  options.local.fs.boot.device = with lib.types; mkOption {
-    type = str;
+  options.local.fs = with lib.types; {
+    impermanence = mkOption {
+      type = bool;
+      default = false;
+    };
+
+    boot.device = mkOption {
+      type = str;
+    };
   };
 
   config = {
     # !!!
     boot.tmpOnTmpfs = true;
 
+    fileSystems."/" = mkIf cfg.impermanence {
+      device = "tmpfs";
+      fsType = "tmpfs";
+      options = [ "size=1G" "mode=755" ];
+    };
+
     fileSystems."/boot" = {
-      inherit (cfg.fs.boot) device;
+      inherit (cfg.boot) device;
       fsType = "vfat";
       options = [ "noatime" "umask=027" ];
     };