stable machine id

common.nix

@@ -123,6 +123,7 @@ in
 
   # keep some stuff persistent
   environment.persistence."/nix/persistent" = {
+    hideMounts = true;
     directories = [
       # systemd timers
       { directory = "/var/lib/systemd/timers"; user = "root"; group = "root"; mode = "u=rwx,g=rx,o=rx"; }
@@ -130,6 +131,9 @@ in
       # clamav database
       { directory = "/var/lib/clamav"; user = "clamav"; group = "clamav"; mode = "u=rwx,g=rx,o=rx"; }
     ];
+    files = [
+      "/etc/machine-id"
+    ];
   };
 
   # enable fast dbus