refactor(wyoming+): assert instead of import docker module

devices/homie/default.nix

@@ -13,6 +13,7 @@ in {
 
     ./modules
 
+    self.nixosModules.docker
     self.nixosModules.kmscon
     self.nixosModules.server
   ];

devices/nos/default.nix

@@ -13,6 +13,7 @@ in {
 
     ./modules
 
+    self.nixosModules.docker
     self.nixosModules.kmscon
     self.nixosModules.server
   ];

nixosModules/default.nix

@@ -7,5 +7,5 @@ self: {
   nvidia = import ./nvidia;
   plymouth = import ./plymouth;
   server = import ./server;
-  wyoming-plus = import ./wyoming-plus self;
+  wyoming-plus = import ./wyoming-plus;
 }

nixosModules/docker/default.nix

@@ -4,9 +4,10 @@ khepri: {
   pkgs,
   ...
 }: let
-  inherit (lib) mkOption types;
+  inherit (lib) mkIf mkOption types;
-
   inherit (config.vars) mainUser;
+
+  cfg = config.khepri;
 in {
   imports = [khepri.nixosModules.default];
 
@@ -18,15 +19,20 @@ in {
         Directory to place persistent data in.
       '';
     };
+
+    storageDriver = mkOption {
+      default = "btrfs"; # I use BTRFS on all my servers
+      type = types.str;
+    };
   };
 
-  config = {
+  config = mkIf (cfg.compositions != {}) {
     users.extraUsers.${mainUser}.extraGroups = ["docker"];
 
     virtualisation = {
       docker = {
         enable = true;
-        storageDriver = "btrfs";
+        storageDriver = cfg.storageDriver;
 
         package = pkgs.docker_27;
 

nixosModules/wyoming-plus/default.nix

@@ -1,4 +1,4 @@
-self: {
+{
   config,
   lib,
   pkgs,
@@ -10,6 +10,7 @@ self: {
     escapeShellArgs
     flatten
     filterAttrs
+    hasAttr
     listToAttrs
     map
     mkEnableOption
@@ -26,8 +27,6 @@ self: {
 
   cfg = config.services.wyoming.openwakeword-docker;
 in {
-  imports = [self.nixosModules.docker];
-
   options.services.wyoming.openwakeword-docker = {
     enable = mkEnableOption "Wyoming openWakeWord server";
 
@@ -114,6 +113,19 @@ in {
   };
 
   config = {
+    assertions = [
+      {
+        assertion =
+          (cfg.enable
+          && hasAttr "khepri" config
+          && hasAttr "rwDataDir" config.khepri) || !cfg.enable;
+        message = ''
+          The module `docker` from this same flake is needed to use
+          this openwakeword implementation.
+        '';
+      }
+    ];
+
     systemd.services = let
       unitNames = attrNames (
         filterAttrs (_: v: v.device == "cpu") config.services.wyoming.faster-whisper.servers
@@ -147,7 +159,4 @@ in {
       };
     };
   };
-
-  # For accurate stack trace
-  _file = ./default.nix;
 }