Added impermenence module and set Incarceron to be imperm so we can test

this

flake.lock

@@ -211,6 +211,21 @@
         "type": "github"
       }
     },
+    "impermanence": {
+      "locked": {
+        "lastModified": 1737831083,
+        "narHash": "sha256-LJggUHbpyeDvNagTUrdhe/pRVp4pnS6wVKALS782gRI=",
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "rev": "4b3e914cdf97a5b536a889e939fb2fd2b043a170",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "impermanence",
+        "type": "github"
+      }
+    },
     "mnw": {
       "locked": {
         "lastModified": 1756659871,
@@ -644,6 +659,7 @@
         "disko": "disko",
         "hardware": "hardware",
         "home-manager": "home-manager",
+        "impermanence": "impermanence",
         "niri-flake": "niri-flake",
         "nix-darwin": "nix-darwin",
         "nix-secrets": "nix-secrets",

flake.nix

@@ -96,6 +96,7 @@
       url = "github:nix-community/home-manager/release-25.05";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+    impermanence.url = "github:nix-community/impermanence";
 
     # 3rd party inputs
     disko = {

hosts/common/core/default.nix

@@ -18,6 +18,7 @@ in {
   imports = lib.flatten [
     inputs.home-manager.${platformModules}.home-manager
     inputs.sops-nix.${platformModules}.sops
+    inputs.impermanence.${platformModules}.impermanence
 
     (map lib.custom.relativeToRoot [
       "hosts/common/core/${platform}.nix"

hosts/common/core/impermanence.nix

@@ -0,0 +1,50 @@
+{
+  lib,
+  config,
+  ...
+}:
+lib.mkIf config.hostSpec.isImpermanent {
+  environment.persistence.${config.hostSpec.persistFolder} = {
+    enable = true;
+    directories = [
+      "/var/log"
+      "/var/lib/bluetooth"
+      "/var/lib/nixos"
+      "/var/lib/systemd/coredump"
+      "/etc/NetworkManager/system-connections"
+    ];
+    files = [
+      "/etc/machine-id"
+    ];
+    users.${config.hostSpec.username} = {
+      directories = [
+        "Downloads"
+        "Music"
+        "Pictures"
+        "Documents"
+        "Videos"
+        "VirtualBox VMs"
+        {
+          directory = ".gnupg";
+          mode = "0700";
+        }
+        {
+          directory = ".ssh";
+          mode = "0700";
+        }
+        {
+          directory = ".nixops";
+          mode = "0700";
+        }
+        {
+          directory = ".local/share/keyrings";
+          mode = "0700";
+        }
+        ".local/share/direnv"
+      ];
+      files = [
+        ".screenrc"
+      ];
+    };
+  };
+}

hosts/nixos/Incarceron/default.nix

@@ -48,6 +48,7 @@
 
   hostSpec = {
     hostName = "Incarceron";
+    isImpermanent = true;
     persistFolder = "/persist";
   };