1 files changed, 16 insertions, 0 deletions
diff --git a/nixos/lib/systemd-unit-options.nix b/nixos/lib/systemd-unit-options.nix
index 1c56b1b9aa0..79c01921781 100644
--- a/nixos/lib/systemd-unit-options.nix
+++ b/nixos/lib/systemd-unit-options.nix
@@ -48,6 +48,22 @@ in rec {
       '';
     };
 
+    overrideStrategy = mkOption {
+      default = "asDropinIfExists";
+      type = types.enum [ "asDropinIfExists" "asDropin" ];
+      description = lib.mdDoc ''
+        Defines how unit configuration is provided for systemd:
+
+        `asDropinIfExists` creates a unit file when no unit file is provided by the package
+        otherwise a drop-in file name `overrides.conf`.
+
+        `asDropin` creates a drop-in file named `overrides.conf`.
+        Mainly needed to define instances for systemd template units (e.g. `systemd-nspawn@mycontainer.service`).
+
+        See also systemd.unit(1).
+      '';
+    };
+
     requiredBy = mkOption {
       default = [];
       type = types.listOf unitNameType;