From 9abcb29cd4c4dab94d100ffc877797bf97cc8dde Mon Sep 17 00:00:00 2001
From: Ilan Joselevich <personal@ilanjoselevich.com>
Date: Thu, 16 Apr 2026 20:54:26 +0100
Subject: [PATCH] nixos/prometheus-postfix-exporter: use socket activation

Run postfix_exporter with `--web.systemd-socket` and move the
listen-address/port configuration into a companion `.socket` unit.
---
 .../services/monitoring/prometheus/exporters/postfix.nix   | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix b/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
index 53a4056b86dd..e0abda068b2f 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
@@ -85,6 +85,7 @@ in
       };
     };
   };
+
   serviceOpts = {
     after = mkIf cfg.systemd.enable [ cfg.systemd.unit ];
     serviceConfig = {
@@ -95,7 +96,7 @@ in
       SupplementaryGroups = mkIf cfg.systemd.enable [ "systemd-journal" ];
       ExecStart = ''
         ${lib.getExe cfg.package} \
-          --web.listen-address ${cfg.listenAddress}:${toString cfg.port} \
+          --web.systemd-socket \
           --web.telemetry-path ${cfg.telemetryPath} \
           --postfix.showq_path ${escapeShellArg cfg.showqPath} \
           ${concatStringsSep " \\\n  " (
@@ -115,4 +116,8 @@ in
       '';
     };
   };
+
+  socketOpts = {
+    socketConfig.ListenStream = "${cfg.listenAddress}:${toString cfg.port}";
+  };
 }