From 57fbdcb3e29f29b48f74dd89f2537d0ea53f3c88 Mon Sep 17 00:00:00 2001
From: Merrkry <merrkry@tsubasa.moe>
Date: Sun, 5 Apr 2026 20:53:56 +0800
Subject: [PATCH] sing-box: allow empty settings

---
 .../modules/services/networking/sing-box.nix  | 15 ++++++----
 nixos/tests/sing-box.nix                      | 28 +++++++++++++++++++
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/nixos/modules/services/networking/sing-box.nix b/nixos/modules/services/networking/sing-box.nix
index c6ae9cb5c290..3076d94e83b9 100644
--- a/nixos/modules/services/networking/sing-box.nix
+++ b/nixos/modules/services/networking/sing-box.nix
@@ -50,6 +50,7 @@ in
       serviceConfig = {
         User = "sing-box";
         Group = "sing-box";
+        ConfigurationDirectory = "sing-box";
         StateDirectory = "sing-box";
         StateDirectoryMode = "0700";
         RuntimeDirectory = "sing-box";
@@ -62,11 +63,15 @@ in
               chown --reference=/run/sing-box /run/sing-box/config.json
             '';
           in
-          "+${script}";
-        ExecStart = [
-          ""
-          "${lib.getExe cfg.package} -D \${STATE_DIRECTORY} -C \${RUNTIME_DIRECTORY} run"
-        ];
+          lib.mkIf (cfg.settings != { }) "+${script}";
+        ExecStart =
+          let
+            configDir = if cfg.settings != { } then "RUNTIME_DIRECTORY" else "CONFIGURATION_DIRECTORY";
+          in
+          [
+            ""
+            "${lib.getExe cfg.package} -D \${STATE_DIRECTORY} -C \${${configDir}} run"
+          ];
       };
       # After= is specified by upstream
       requires = [ "network-online.target" ];
diff --git a/nixos/tests/sing-box.nix b/nixos/tests/sing-box.nix
index cc890fa6fe69..820675d69a11 100644
--- a/nixos/tests/sing-box.nix
+++ b/nixos/tests/sing-box.nix
@@ -511,6 +511,31 @@ in
           };
         };
       };
+
+    empty_settings =
+      { ... }:
+      {
+        environment.etc."sing-box/config.json".text = builtins.toJSON {
+          inbounds = [
+            {
+              type = "mixed";
+              listen = "127.0.0.1";
+              listen_port = 1088;
+            }
+          ];
+          outbounds = [
+            {
+              type = "direct";
+              tag = "outbound:direct";
+            }
+          ];
+        };
+
+        services.sing-box = {
+          enable = true;
+          settings = { };
+        };
+      };
   };
 
   testScript = ''
@@ -558,6 +583,9 @@ in
       fakeip.wait_for_unit("sing-box.service")
       fakeip.wait_until_succeeds("ip route get ${hosts."${target_host}"} | grep 'dev ${tunInbound.interface_name}'")
       fakeip.succeed("dig +short A ${target_host} @${target_host} | grep '^198.18.'")
+
+    with subtest("empty settings"):
+      empty_settings.wait_for_unit("sing-box.service")
   '';
 
 }