WIP introduce nixos module system for configuration

merge-modules.nix

@@ -0,0 +1,8 @@
+module : initial : pkgs :
+let evalModules = (import <nixpkgs/lib>).evalModules;
+in evalModules {
+  modules = [
+    { _module.args = { inherit pkgs; }; }
+    module
+  ];
+}

tests/module/configuration.nix

@@ -0,0 +1,10 @@
+{ config, pkgs, ... } :
+{
+  imports = [ ./defs.nix ./module.nix ];
+  config = {
+    services.a.enable = true;
+    services.b.enable = true;
+
+    systemPackages = [ pkgs.hello ] ;
+  };
+}

tests/module/defs.nix

@@ -0,0 +1,16 @@
+{ lib, ...}:
+let inherit (lib) mkEnableOption mkOption types;
+in {
+  options = {
+    services.a = {
+      enable = mkEnableOption "hello service";
+    };
+    services.b = {
+      enable = mkEnableOption "other service";
+    };
+    services.z = mkOption {   };
+    systemPackages = mkOption {
+      type = types.listOf types.package;
+    };
+  };
+}

tests/module/module.nix

@@ -0,0 +1,6 @@
+{ config, pkgs, ... } :
+{
+  services.z = pkgs.figlet;
+
+  systemPackages = [ pkgs.units ] ;
+}

tests/module/run.sh

@@ -0,0 +1,2 @@
+set -e
+NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM=1 nix-build --arg device "import <liminix/devices/qemu.nix>" test.nix

tests/module/test.nix

@@ -0,0 +1,17 @@
+{ device }:
+let
+  overlay = import <liminix/overlay.nix> ;
+  nixpkgs = import <nixpkgs> ( device.system // {overlays = [overlay]; });
+  inherit (nixpkgs) lib pkgs;
+  inherit (lib.asserts) assertMsg;
+  config =
+    (import <liminix/merge-modules.nix>) ./configuration.nix {} pkgs;
+  res1 = assertMsg
+    # check we have packages from both modules
+    (config.config.systemPackages == ( with pkgs; [ units hello ])) "failed";
+  res2 = let s = config.config.services;
+         in assertMsg (s.a.enable && s.b.enable && (s.z != null) ) "failed";
+in pkgs.writeText "foo" ''
+   ${if res1 then "OK" else "not OK"}
+   ${if res2 then "OK" else "not OK"}
+''