From 6ccc6bf4d2a6fac38236f7453149e402e443721e Mon Sep 17 00:00:00 2001
From: r-vdp <ramses@well-founded.dev>
Date: Wed, 4 Sep 2024 12:17:39 +0200
Subject: [PATCH] initrd: emit a warning when tmpfiles config is created
 manually

---
 nixos/modules/system/boot/systemd/tmpfiles.nix | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/nixos/modules/system/boot/systemd/tmpfiles.nix b/nixos/modules/system/boot/systemd/tmpfiles.nix
index f609da314c86..44c72f2768cc 100644
--- a/nixos/modules/system/boot/systemd/tmpfiles.nix
+++ b/nixos/modules/system/boot/systemd/tmpfiles.nix
@@ -163,6 +163,20 @@ in
   };
 
   config = {
+    warnings =
+      let
+        paths = lib.filter (path:
+          path != null && lib.hasPrefix "/etc/tmpfiles.d/" path
+        ) (map (path: path.target) config.boot.initrd.systemd.storePaths);
+      in
+      lib.optional (lib.length paths > 0) (lib.concatStringsSep " " [
+        "Files inside /etc/tmpfiles.d in the initrd need to be created with"
+        "boot.initrd.systemd.tmpfiles.settings."
+        "Creating them by hand using boot.initrd.systemd.contents or"
+        "boot.initrd.systemd.storePaths will lead to errors in the future."
+        "Found these problematic files: ${lib.concatStringsSep ", " paths}"
+      ]);
+
     systemd.additionalUpstreamSystemUnits = [
       "systemd-tmpfiles-clean.service"
       "systemd-tmpfiles-clean.timer"