Enable preservation for SIIT-DC

hosts/siit-dc/configuration.nix

@@ -1,6 +1,7 @@
-{ ... }:
+{ lib, ... }:
 {
-  networking.hostId = "f1636fe0";
+  preservation.enable = true;
+  swapDevices = lib.mkForce [ ];
   imports = [
     ../../shared/base.nix
 

hosts/siit-dc/state.nix

@@ -1,5 +1,6 @@
 { lib, modulesPath, ... }:
 {
+  networking.hostId = "f1636fe0";
   networking.networkmanager.enable = lib.mkForce false;
   networking.useDHCP = false;
   systemd.network.enable = true;

shared/base.nix

@@ -34,6 +34,35 @@
       ssss
     ];
 
+    ######################################## Preservation ###########################################
+    preservation = {
+      enable = lib.mkDefault false;
+      preserveAt."/persist" = {
+        files = [
+          {
+            file = "/etc/machine-id";
+            inInitrd = true;
+          }
+          {
+            file = "/etc/ssh/ssh_host_rsa_key";
+            how = "symlink";
+            inInitrd = true; # sops-nix
+          }
+          {
+            file = "/etc/ssh/ssh_host_ed25519_key";
+            how = "symlink";
+            inInitrd = true; # sops-nix
+          }
+        ];
+        directories = [
+          "/var/lib/systemd/timers"
+          "/var/lib/nixos"
+          "/var/log"
+        ];
+      };
+    };
+    systemd.suppressedSystemUnits = [ "systemd-machine-id-commit.service" ];
+
     ######################################## ZSH configuration ######################################
     users.defaultUserShell = pkgs.zsh;
     environment.shells = with pkgs; [ zsh ];