modules/openssh-pregenerated: use persistent key file path

Signed-off-by: Sefa Eyeoglu <[email protected]>

modules/openssh-pregenerated.nix

@@ -1,13 +1,15 @@
 let
   keyFile = "/etc/ssh/ssh_host_ed25519_key";
+  persistentKeyFile = "/nix/persistence/${keyFile}";
 in
 {
   services.openssh = {
     hostKeys = [ ];
     settings.HostKey = keyFile;
   };
 
+  # age will be activated, before impermanence mounts persistent files and directories. A workaround is to specify the persistent path for the key file
   age.identityPaths = [
-    keyFile
+    persistentKeyFile
   ];
 }