4 files changed, 59 insertions, 2 deletions
diff --git a/nixos/modules/config/i18n.nix b/nixos/modules/config/i18n.nix
index 8182b8ae8081..7a7d713ef687 100644
--- a/nixos/modules/config/i18n.nix
+++ b/nixos/modules/config/i18n.nix
@@ -76,7 +76,7 @@ in
 
     environment.systemPackages = [ glibcLocales ];
 
-    environment.variables =
+    environment.systemVariables =
       { LANG = config.i18n.defaultLocale;
         LOCALE_ARCHIVE = "/run/current-system/sw/lib/locale/locale-archive";
       };
diff --git a/nixos/modules/config/shells-environment.nix b/nixos/modules/config/shells-environment.nix
index 9e212847e489..e3ddf9e3c5fa 100644
--- a/nixos/modules/config/shells-environment.nix
+++ b/nixos/modules/config/shells-environment.nix
@@ -19,6 +19,7 @@ in
       default = {};
       description = ''
         A set of environment variables used in the global environment.
+        These variables will be set on shell initialisation.
         The value of each variable can be either a string or a list of
         strings.  The latter is concatenated, interspersed with colon
         characters.
diff --git a/nixos/modules/config/system-environment.nix b/nixos/modules/config/system-environment.nix
new file mode 100644
index 000000000000..b30c4e064750
--- /dev/null
+++ b/nixos/modules/config/system-environment.nix
@@ -0,0 +1,56 @@
+# This module defines a system-wide environment that will be
+# initialised by pam_env (that is, not only in shells).
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.environment;
+
+in
+
+{
+
+  options = {
+
+    environment.systemVariables = mkOption {
+      default = {};
+      description = ''
+        A set of environment variables used in the global environment.
+        These variables will be set by PAM.
+        The value of each variable can be either a string or a list of
+        strings.  The latter is concatenated, interspersed with colon
+        characters.
+      '';
+      type = types.attrsOf (mkOptionType {
+        name = "a string or a list of strings";
+        merge = loc: defs:
+          let
+            defs' = filterOverrides defs;
+            res = (head defs').value;
+          in
+          if isList res then concatLists (getValues defs')
+          else if lessThan 1 (length defs') then
+            throw "The option `${showOption loc}' is defined multiple times, in ${showFiles (getFiles defs)}."
+          else if !isString res then
+            throw "The option `${showOption loc}' does not have a string value, in ${showFiles (getFiles defs)}."
+          else res;
+      });
+      apply = mapAttrs (n: v: if isList v then concatStringsSep ":" v else v);
+    };
+
+  };
+
+  config = {
+
+    system.build.pamEnvironment = pkgs.writeText "pam-environment"
+       ''
+         ${concatStringsSep "\n" (
+           (mapAttrsToList (n: v: ''${n}="${concatStringsSep ":" v}"'')
+             (zipAttrsWith (const concatLists) ([ (mapAttrs (n: v: [ v ]) cfg.systemVariables) ]))))}
+       '';
+
+  };
+
+}
diff --git a/nixos/modules/config/timezone.nix b/nixos/modules/config/timezone.nix
index 65703d8bb080..4f7fc9ab262b 100644
--- a/nixos/modules/config/timezone.nix
+++ b/nixos/modules/config/timezone.nix
@@ -30,7 +30,7 @@ in
 
   config = {
 
-    environment.variables.TZDIR = "/etc/zoneinfo";
+    environment.systemVariables.TZDIR = "/etc/zoneinfo";
 
     systemd.globalEnvironment.TZDIR = tzdir;