[#9] first impermanence config support

nixos/roles/default.nix

@@ -1,4 +1,32 @@
-{ ... } : {
+{pkgs, config, lib, ...} : {
+
+imports = [
+  ./admins.nix
+  ./nix_keys.nix
+  ../modules/impermanence.nix
+  ];
+nix = {
+  extraOptions = ''
+    experimental-features = nix-command flakes
+    builders-use-substitutes = true
+  '';
+};
+
+networking = {
+  firewall = { # these shoud be default, but better make sure!
+    enable = true;
+    allowPing = true;
+  };
+  nftables.enable = true;
+  useDHCP = false; # We don't speak DHCP and even if we would, we should enable it per interface
+  # hosts = # TODO write something to autogenerate ip adresses!
+};
+
+users = {
+  mutableUsers = false;
+};
+
+impermanence.enable = true;
 
 sops.age.sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
 }