From 8d74aeac0bb9772546c4c45938f70250acffe6d0 Mon Sep 17 00:00:00 2001
From: Yan Lin <github@yanlincs.com>
Date: Wed, 22 Oct 2025 09:54:03 +0200
Subject: [PATCH] add borg lock mechanism

---
 modules/borg-client.nix | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/modules/borg-client.nix b/modules/borg-client.nix
index c1a5dae..9c64cf9 100644
--- a/modules/borg-client.nix
+++ b/modules/borg-client.nix
@@ -158,14 +158,23 @@ in
       description = "Borg Backup Service";
       wants = [ "network-online.target" ];
       after = [ "network-online.target" ];
-      
+
       # Add borg and required tools to the service's PATH
       path = [ pkgs.borgbackup pkgs.openssh pkgs.curl ];
 
+      # Prevent concurrent backup runs
+      unitConfig = {
+        ConditionPathExists = "!/var/run/borg-backup.lock";
+      };
+
       serviceConfig = {
         Type = "oneshot";
         User = "root";  # Need root to access all backup paths
         Group = "root";
+
+        # Create lock file on start, remove on stop
+        ExecStartPre = "${pkgs.coreutils}/bin/touch /var/run/borg-backup.lock";
+        ExecStopPost = "${pkgs.coreutils}/bin/rm -f /var/run/borg-backup.lock";
         
         # Security settings
         PrivateTmp = true;