From 815de32c44ef9974cfc1b6649579df85ca9d325d Mon Sep 17 00:00:00 2001
From: Dirk Heilig <heilig@adesso-mobile.de>
Date: Fri, 16 Aug 2024 14:36:40 +0200
Subject: [PATCH] add retained-ignore

---
 Readme.md     | 6 +++++-
 mqtt2prom/run | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Readme.md b/Readme.md
index 6dbc4dc..3d3cd40 100644
--- a/Readme.md
+++ b/Readme.md
@@ -12,9 +12,13 @@ MQTT_PASS
 MQTT_CLIENT_ID|mqtt2prometheus
 MQTT_TOPIC|prometheus
 MQTT_QOS|2
-
+IGNORE_RETAINED|1
 ```
 
+
+
+`IGNORE_RETAINED`: when set, retained messages are dropped and will be reported as errors.
+
 it will listen on the configured mqtt server at `$MQTT_TOPIC` for metrics in json_format.
 
 The payload needs to be an object containing only the following keys:
diff --git a/mqtt2prom/run b/mqtt2prom/run
index ba6523c..9e9b209 100755
--- a/mqtt2prom/run
+++ b/mqtt2prom/run
@@ -24,6 +24,8 @@ $mqttPass = getEnvWithDefaultStr("MQTT_PASS", "");
 $mqttClientId = getEnvWithDefaultStr("MQTT_CLIENT_ID", "mqtt2prometheus");
 $mqttTopic = getEnvWithDefaultStr("MQTT_TOPIC", "prometheus");
 $qos = getEnvWithDefaultInt("MQTT_QOS", 2);
+$ignoreRetained = getEnvWithDefaultInt("IGNORE_RETAINED", 1)?1:0;
+
 
 $serviceReloadTime = getEnvWithDefaultStr("SERVICE_RELOAD_TIME", "03:30");
 
@@ -41,6 +43,7 @@ $usedConfig = [
     "MQTT_TOPIC" => $mqttTopic,
     "MQTT_QOS" => $qos,
     "SERVICE_RELOAD_TIME" => $serviceReloadTime,
+    "IGNORE_RETAINED" => $ignoreRetained,
 ];
 
 $padLength = max(array_map("strlen", array_keys($usedConfig)));
@@ -115,6 +118,11 @@ function error(string $msg): void
 }
 function precheck(Message $message): bool
 {
+    global $ignoreRetained;
+    if($ignoreRetained && $message->retain){
+        error("Ignoring retained message");
+        return false;
+    }
     $payloadRaw = $message->payload;
     $payload = json_decode($payloadRaw, true);
     if (json_last_error() != JSON_ERROR_NONE) {