[#9] first impermanence config support

nixos/flake-module.nix

@@ -12,6 +12,7 @@
           imports = [
             (import (./. + "/machines/${name}/configuration.nix") inputs)
             inputs.sops-nix.nixosModules.sops
+            inputs.impermanence.nixosModules.impermanence
           ];
         };
     in lib.genAttrs machines makeSystem);

nixos/modules/impermanence.nix

@@ -0,0 +1,42 @@
+{lib, config, ...} :
+
+let 
+  inherit (lib)
+    mkEnableOption
+    mkIf
+    mkOption
+    types
+    ;
+  cfg = config.impermanence;
+in
+
+{
+imports = [ ];
+
+options.impermanence = {
+  enable = mkEnableOption "impermanence";
+  storagePath = mkOption {
+    type = types.path;
+    default = "/persist/persist";
+    description = "The path where persistent data is stored";
+  };
+  name = mkOption {
+    type = types.str;
+    default = "persist";
+    description = "the name of the persistent data store";
+  };
+};
+
+config = mkIf cfg.enable {
+  environment.persistence.${cfg.name} = {
+    persistentStoragePath = cfg.storagePath;
+    directories = [
+      "/var/log"
+      "/etc/ssh"
+      "/var/lib/nixos"
+    ];
+  };
+  environment.etc.machine-id.source = "${cfg.storagePath}/machine-id";
+};
+
+}

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" ];
 }