From 9abcf007c789701710b1a40dc84007dc773da5b2 Mon Sep 17 00:00:00 2001
From: HeHongbo <hehongbo@mail.com>
Date: Tue, 8 Oct 2024 02:11:07 +0800
Subject: [PATCH 1/2] collectd: bring back xencpu plugin

---
 pkgs/tools/system/collectd/plugins.nix | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pkgs/tools/system/collectd/plugins.nix b/pkgs/tools/system/collectd/plugins.nix
index 7202ec795e8b2..9fe1f1d185d40 100644
--- a/pkgs/tools/system/collectd/plugins.nix
+++ b/pkgs/tools/system/collectd/plugins.nix
@@ -39,8 +39,7 @@
 , xen
 , yajl
 , IOKit
-# Defaults to `null` for all supported plugins (except xen, which is marked as
-# insecure), otherwise a list of plugin names for a custom build
+# Defaults to `null` for all supported plugins list of plugin names for a custom build
 , enabledPlugins ? null
 , ...
 }:
@@ -134,7 +133,8 @@ let
   buildInputs =
     if enabledPlugins == null
     then builtins.concatMap pluginBuildInputs
-      (builtins.attrNames (builtins.removeAttrs plugins ["xencpu"]))
+      (builtins.attrNames (
+        builtins.removeAttrs plugins (lib.optional (!lib.meta.availableOn stdenv.hostPlatform xen) "xencpu")))
     else builtins.concatMap pluginBuildInputs enabledPlugins;
 in {
   inherit configureFlags buildInputs;

From c1a8455bf36031662aa853702f76c10b8e6f4623 Mon Sep 17 00:00:00 2001
From: HeHongbo <hehongbo@mail.com>
Date: Tue, 8 Oct 2024 14:27:14 +0800
Subject: [PATCH 2/2] collectd: show warning if the xencpu plugin is enabled
 without root

---
 nixos/modules/services/monitoring/collectd.nix | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/nixos/modules/services/monitoring/collectd.nix b/nixos/modules/services/monitoring/collectd.nix
index fe9b1214e5c12..4fb439d5b52b8 100644
--- a/nixos/modules/services/monitoring/collectd.nix
+++ b/nixos/modules/services/monitoring/collectd.nix
@@ -104,6 +104,14 @@ in {
   };
 
   config = mkIf cfg.enable {
+    warnings = lib.optional ((cfg.plugins ? xencpu) || cfg.user == "root") ''
+      The xencpu plugin for collectd typically requires root privileges. You
+      have enabled the xencpu plugin but collectd is not configured to run as
+      root. If you're running in a Xen dom0 environment and want to collect
+      metrics of hardware CPU load, you may need
+      `services.collectd.user = "root"`;
+    '';
+
     # 1200 is after the default (1000) but before mkAfter (1500).
     services.collectd.extraConfig = lib.mkOrder 1200 ''
       ${baseDirLine}