From 487689b35d0388e71464e7e384d60d321ca1ac16 Mon Sep 17 00:00:00 2001
From: Maximilian Bosch <maximilian@mbosch.me>
Date: Thu, 16 Jun 2022 23:36:28 +0200
Subject: [PATCH] nixos/prometheus-postfix-exporter: fixes for systemd
 integration

* Allow the service to read from the journal w/systemd.enable
* Ensure that the service is started after postfix.service

(cherry picked from commit 1f9375b92e8236b4881f080e3b43d8db8db2dc68)
---
 .../services/monitoring/prometheus/exporters/postfix.nix        | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix b/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
index 4d3c1fa267e5..53509b7a385b 100644
--- a/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
+++ b/nixos/modules/services/monitoring/prometheus/exporters/postfix.nix
@@ -74,11 +74,13 @@ in
     };
   };
   serviceOpts = {
+    after = mkIf cfg.systemd.enable [ cfg.systemd.unit ];
     serviceConfig = {
       DynamicUser = false;
       # By default, each prometheus exporter only gets AF_INET & AF_INET6,
       # but AF_UNIX is needed to read from the `showq`-socket.
       RestrictAddressFamilies = [ "AF_UNIX" ];
+      SupplementaryGroups = mkIf cfg.systemd.enable [ "systemd-journal" ];
       ExecStart = ''
         ${pkgs.prometheus-postfix-exporter}/bin/postfix_exporter \
           --web.listen-address ${cfg.listenAddress}:${toString cfg.port} \