From 1fc937818d2919cf83e78a2e1357537f820db9ea Mon Sep 17 00:00:00 2001
From: networkException <git@nwex.de>
Date: Sun, 15 Dec 2024 19:13:48 +0100
Subject: [PATCH] nixos/wireguard-networkd: fix systemd credentials not working
 with multiple keys per interface

This patch fixes systemd credential loading for wireguard
with networkd not working when specifying more than one
credential per interface by properly flattening the resulting
multidimensional list instead of falling back on string concat
with a space.

Resolves #365402
---
 .../services/networking/wireguard-networkd.nix        | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/services/networking/wireguard-networkd.nix b/nixos/modules/services/networking/wireguard-networkd.nix
index 931f3305594c..ad7de97f1e5a 100644
--- a/nixos/modules/services/networking/wireguard-networkd.nix
+++ b/nixos/modules/services/networking/wireguard-networkd.nix
@@ -14,7 +14,12 @@ let
     mapAttrsToList
     nameValuePair
     ;
-  inherit (lib.lists) concatMap concatLists filter;
+  inherit (lib.lists)
+    concatMap
+    concatLists
+    filter
+    flatten
+    ;
   inherit (lib.modules) mkIf;
   inherit (lib.options) literalExpression mkOption;
   inherit (lib.strings) hasInfix;
@@ -215,7 +220,9 @@ in
 
     systemd.timers = mapAttrs' generateRefreshTimer refreshEnabledInterfaces;
     systemd.services = (mapAttrs' generateRefreshService refreshEnabledInterfaces) // {
-      systemd-networkd.serviceConfig.LoadCredential = mapAttrsToList interfaceCredentials cfg.interfaces;
+      systemd-networkd.serviceConfig.LoadCredential = flatten (
+        mapAttrsToList interfaceCredentials cfg.interfaces
+      );
     };
   };
 }