Add modules

modules/environment/path.nix

@@ -0,0 +1,67 @@
+# Licensed under GNU Lesser General Public License v3 or later, see COPYING.
+# Copyright (c) 2019 Alexander Sosedkin and other contributors, see AUTHORS.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.environment;
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    environment = {
+      packages = mkOption {
+        type = types.listOf types.package;
+        default = [];
+        description = "List of packages to be installed as user packages.";
+      };
+
+      path = mkOption {
+        type = types.package;
+        readOnly = true;
+        internal = true;
+        description = "Derivation for installing user packages.";
+      };
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    build.activation.installPackages = ''
+      $DRY_RUN_CMD nix-env --install ${cfg.path}
+    '';
+
+    environment = {
+      packages = [
+        (pkgs.callPackage ../../nix-on-droid { })
+        pkgs.bashInteractive
+        pkgs.cacert
+        pkgs.coreutils
+        pkgs.less  # since nix tools really want a pager available, #27
+        pkgs.nix
+      ];
+
+      path = pkgs.buildEnv {
+        name = "nix-on-droid-path";
+
+        paths = cfg.packages;
+
+        meta = {
+          description = "Environment of packages installed through nix-on-droid.";
+        };
+      };
+    };
+
+  };
+
+}