Mask systemd-networkd-wait-online.service during boot (#13611)

Author: OneBlue

src/linux/init/init.cpp

@@ -329,6 +329,10 @@ int GenerateSystemdUnits(int Argc, char** Argv)
             File.reset();
         }
 
+        // Mask systemd-networkd-wait-online.service since WSL always ensures that networking is configured during boot.
+        // That unit can cause systemd boot timeouts since WSL's network interface is unmanaged by systemd.
+        THROW_LAST_ERROR_IF(symlink("/dev/null", std::format("{}/systemd-networkd-wait-online.service", installPath).c_str()) < 0);
+
         // Only create the wslg unit if both enabled in wsl.conf, and if the wslg folder actually exists.
         if (enableGuiApps && access("/mnt/wslg/runtime-dir", F_OK) == 0)
         {

test/windows/UnitTests.cpp

@@ -211,6 +211,12 @@ class UnitTests
 
         auto revert = EnableSystemd();
         VERIFY_IS_TRUE(IsSystemdRunning(L"--system"));
+
+        // Validate that systemd-networkd-wait-online.service is masked.
+        auto [out, _] =
+            LxsstuLaunchWslAndCaptureOutput(L"systemctl status systemd-networkd-wait-online.service  | grep -iF Loaded:");
+
+        VERIFY_ARE_EQUAL(out, L"     Loaded: masked (Reason: Unit systemd-networkd-wait-online.service is masked.)\n");
     }
 
     TEST_METHOD(SystemdUser)