From 3f1354a3cd61d37d9b5c91706945f849c9af71c4 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Wed, 5 Aug 2015 12:03:19 +0200
Subject: [PATCH] =?UTF-8?q?Add=20an=20option=20=E2=80=98nix.nixPath?=
 =?UTF-8?q?=E2=80=99=20for=20specifying=20$NIX=5FPATH?=
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---
 nixos/modules/programs/environment.nix     |  9 ---------
 nixos/modules/services/misc/nix-daemon.nix | 19 ++++++++++++++++++-
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/nixos/modules/programs/environment.nix b/nixos/modules/programs/environment.nix
index dce757ceb623..52f6cc221119 100644
--- a/nixos/modules/programs/environment.nix
+++ b/nixos/modules/programs/environment.nix
@@ -23,15 +23,6 @@ in
         EDITOR = mkDefault "nano";
       };
 
-    environment.sessionVariables =
-      { NIX_PATH =
-          [ "/nix/var/nix/profiles/per-user/root/channels/nixos"
-            "nixpkgs=/etc/nixos/nixpkgs"
-            "nixos-config=/etc/nixos/configuration.nix"
-            "/nix/var/nix/profiles/per-user/root/channels"
-          ];
-      };
-
     environment.profiles =
       [ "$HOME/.nix-profile"
         "/nix/var/nix/profiles/default"
diff --git a/nixos/modules/services/misc/nix-daemon.nix b/nixos/modules/services/misc/nix-daemon.nix
index 4088f9ff055d..7c42076280c2 100644
--- a/nixos/modules/services/misc/nix-daemon.nix
+++ b/nixos/modules/services/misc/nix-daemon.nix
@@ -309,6 +309,21 @@ in
         '';
       };
 
+      nixPath = mkOption {
+        type = types.listOf types.str;
+        default =
+          [ "/nix/var/nix/profiles/per-user/root/channels/nixos"
+            "nixpkgs=/etc/nixos/nixpkgs"
+            "nixos-config=/etc/nixos/configuration.nix"
+            "/nix/var/nix/profiles/per-user/root/channels"
+          ];
+        description = ''
+          The default Nix expression search path, used by the Nix
+          evaluator to look up paths enclosed in angle brackets
+          (e.g. <literal>&lt;nixpkgs&gt;</literal>).
+        '';
+      };
+
     };
 
   };
@@ -378,7 +393,9 @@ in
       };
 
     # Set up the environment variables for running Nix.
-    environment.sessionVariables = cfg.envVars;
+    environment.sessionVariables = cfg.envVars //
+      { NIX_PATH = concatStringsSep ":" cfg.nixPath;
+      };
 
     environment.extraInit =
       ''