systemd: Add support for path units.

This allows to define systemd.path(5) units, for example like this:

{
  systemd = let
    description = "Set Key Permissions for xyz.key";
  in {
    paths.set-key-perms = {
      inherit description;
      before = [ "network.target" ];
      wantedBy = [ "multi-user.target" ];
      pathConfig.PathChanged = "/run/keys/xyz.key";
    };

    services.set-key-perms = {
      inherit description;
      serviceConfig.Type = "oneshot";
      script = "chown myspecialkeyuser /run/keys/xyz.key";
    };
  };
}

The example here is actually useful in order to set permissions for the
NixOps keys target to ensure those permisisons aren't reset whenever the
key file is reuploaded.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/nixos/modules/system/boot/systemd-unit-options.nix b/nixos/modules/system/boot/systemd-unit-options.nix
index 113990814ef..d9dc6549f36 100644
--- a/nixos/modules/system/boot/systemd-unit-options.nix
+++ b/nixos/modules/system/boot/systemd-unit-options.nix
@@ -321,6 +321,23 @@ in rec {
   };
 
 
+  pathOptions = unitOptions // {
+
+    pathConfig = mkOption {
+      default = {};
+      example = { PathChanged = "/some/path"; Unit = "changedpath.service"; };
+      type = types.attrsOf unitOption;
+      description = ''
+        Each attribute in this set specifies an option in the
+        <literal>[Path]</literal> section of the unit.  See
+        <citerefentry><refentrytitle>systemd.path</refentrytitle>
+        <manvolnum>5</manvolnum></citerefentry> for details.
+      '';
+    };
+
+  };
+
+
   mountOptions = unitOptions // {
 
     what = mkOption {