From 29bdb29ab29bc50c90b91de29e982401e8a16328 Mon Sep 17 00:00:00 2001
From: Andreas Fuchs <asf@boinkor.net>
Date: Tue, 28 Apr 2026 11:19:07 -0400
Subject: [PATCH] vmalert: Fail if encountering missing rule paths

Previously, when using toString for interpolating paths, the build process wouldn't attempt to copy the given path into the store; that would then result in hard-to-debug errors when running the vmalert service (it launches, but treats the missing as a non-issue, so you run with no alerting).

Instead, use string interpolation to resolve the file from the given path. This properly fails the build if a missing file is referenced.
---
 nixos/modules/services/monitoring/vmalert.nix | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/services/monitoring/vmalert.nix b/nixos/modules/services/monitoring/vmalert.nix
index 0baaa039e395..6dc6a6dc6043 100644
--- a/nixos/modules/services/monitoring/vmalert.nix
+++ b/nixos/modules/services/monitoring/vmalert.nix
@@ -25,14 +25,16 @@ let
     in
     attrsOf (either valueType (listOf valueType));
 
+  mkCliVal = value: if isPath value then "${value}" else toString value;
+
   mkLine =
     key: value:
     if value == true then
       "-${key}"
     else if isList value then
-      concatMapStringsSep " " (v: "-${key}=${escapeShellArg (toString v)}") value
+      concatMapStringsSep " " (v: "-${key}=${escapeShellArg (mkCliVal v)}") value
     else
-      "-${key}=${escapeShellArg (toString value)}";
+      "-${key}=${escapeShellArg (mkCliVal value)}";
 
   vmalertName = name: "vmalert" + lib.optionalString (name != "") ("-" + name);
   enabledInstances = lib.filterAttrs (name: conf: conf.enable) config.services.vmalert.instances;