From b7b2e0bc6572fc66c9c13079b71c6aa9abbd7bac Mon Sep 17 00:00:00 2001
From: Ingo Ratsdorf <ingo@envirology.co.nz>
Date: Fri, 27 Sep 2024 12:24:46 +1200
Subject: [PATCH] fixes to MQTT publisher

This wasn't working for EMQX due to callback trigger delays it never connected. Also added a reconnect feature and a client id so it looks better in the EMQX connection dashboard. No confirmed to be working with Mosquitto and EMQX
---
 front/plugins/_publisher_mqtt/mqtt.py | 54 ++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 9 deletions(-)

diff --git a/front/plugins/_publisher_mqtt/mqtt.py b/front/plugins/_publisher_mqtt/mqtt.py
index 20df275c..b29b10f3 100755
--- a/front/plugins/_publisher_mqtt/mqtt.py
+++ b/front/plugins/_publisher_mqtt/mqtt.py
@@ -273,29 +273,54 @@ def create_sensor(mqtt_client, deviceId, deviceName, sensorType, sensorName, ico
 #-------------------------------------------------------------------------------
 def mqtt_create_client():
 
+    # attempt reconnections on failure, ref https://www.emqx.com/en/blog/how-to-use-mqtt-in-python
+    FIRST_RECONNECT_DELAY = 1
+    RECONNECT_RATE = 2
+    MAX_RECONNECT_COUNT = 12
+    MAX_RECONNECT_DELAY = 60
+    
     mytransport = 'tcp' # or 'websockets'
 
-    def on_disconnect(mqtt_client, userdata, reason_code):
+    def on_disconnect(mqtt_client, userdata, rc):
         
         global mqtt_connected_to_broker
 
-        # REF: If we wanted a auto reconnect, a good source is here: https://www.emqx.com/en/blog/how-to-use-mqtt-in-python
-        mqtt_connected_to_broker = False
-        mylog('debug', [f"[{pluginName}]         Connection terminated, reason_code: {reason_code}"])
+        mylog('debug', [f"[{pluginName}]         Connection terminated, reason_code: {rc}"])
+        reconnect_count, reconnect_delay = 0, FIRST_RECONNECT_DELAY
+        while reconnect_count < MAX_RECONNECT_COUNT:
+            mylog('debug', [f"[{pluginName}]         Reconnecting in {reconnect_delay} seconds..."])
+            time.sleep(reconnect_delay)
 
-    def on_connect(mqtt_client, userdata, flags, reason_code, properties):
+            try:
+                mqtt_client.reconnect()
+                mqtt_connected_to_broker = True     # Signal connection 
+                mylog('debug', [f"[{pluginName}]         Reconnected successfully"])
+                return
+            except Exception as err:
+                mylog('debug', [f"[{pluginName}]         {err} Reconnect failed. Retrying..."])
+                pass
+
+            reconnect_delay *= RECONNECT_RATE
+            reconnect_delay = min(reconnect_delay, MAX_RECONNECT_DELAY)
+            reconnect_count += 1
+            
+        mqtt_connected_to_broker = False
+        
+
+    def on_connect(mqtt_client, userdata, flags, rc, properties):
         
         global mqtt_connected_to_broker
 
         # REF: Good docu on reason codes: https://www.emqx.com/en/blog/mqtt5-new-features-reason-code-and-ack
-        if reason_code == 0: 
+        if rc == 0: 
             mylog('verbose', [f"[{pluginName}]         Connected to broker"])            
             mqtt_connected_to_broker = True     # Signal connection 
         else: 
-            mylog('verbose', [f"[{pluginName}]         Connection failed, reason_code: {reason_code}"])
+            mylog('verbose', [f"[{pluginName}]         Connection failed, reason_code: {rc}"])
             mqtt_connected_to_broker = False
 
     global mqtt_client
+    global mqtt_connected_to_broker
 
     # Paho will be soon not supporting V1 anymore, so this really should not be a user choice to start with
     # This code now uses V2 by default
@@ -306,10 +331,13 @@ def mqtt_create_client():
     else:
         version = mqtt.MQTTv5
 
+    # we now hardcode the client id into here.
+    # TODO: Add config ffor client id
     mqtt_client = mqtt.Client(
+        client_id='netalertx',
         callback_api_version = mqtt.CallbackAPIVersion.VERSION2,
         transport=mytransport,
-        protocol=mqtt.MQTTv5)
+        protocol=version)
     mqtt_client.on_connect = on_connect
     mqtt_client.on_disconnect = on_disconnect
 
@@ -317,7 +345,15 @@ def mqtt_create_client():
         mqtt_client.tls_set()
 
     mqtt_client.username_pw_set(username = get_setting_value('MQTT_USER'), password = get_setting_value('MQTT_PASSWORD'))    
-    mqtt_client.connect(host = get_setting_value('MQTT_BROKER'), port = get_setting_value('MQTT_PORT'))
+    err_code = mqtt_client.connect(host = get_setting_value('MQTT_BROKER'), port = get_setting_value('MQTT_PORT'))
+    if (err_code == mqtt.MQTT_ERR_SUCCESS):
+        # We (prematurely) set the connection state to connected
+        # the callback may be delayed
+        mqtt_connected_to_broker = True
+    # the client connects but connect callbacks will be called async and there may be a waiting time
+    # Mosquitto works straight away
+    # EMQX has a delay and does not update in loop below, so we cannot rely on it, we wait 1 sec
+    time.sleep(1)
     mqtt_client.loop_start() 
 
     return mqtt_client