Make MqttClient a singleton

app/mod_devices/__init__.py

@@ -3,12 +3,13 @@ from flask import Blueprint
 from .mqtt_client import MqttClient
 
 devices = Blueprint('devices', __name__)
-mqtt_client = MqttClient()
+mqtt_client = None
 
 
 # When app dies, stop mqtt connection
 def on_stop():
-    mqtt_client.tear_down()
+    if mqtt_client:
+        mqtt_client.tear_down()
 
 
 atexit.register(on_stop)
@@ -22,4 +23,8 @@ def hello():
 
 @devices.record
 def on_blueprint_setup(setup_state):
-    mqtt_client.setup(setup_state.app)
+    print('Blueprint setup')
+    mqtt_client = MqttClient()
+
+    if mqtt_client:
+        mqtt_client.setup(setup_state.app)

app/mod_devices/mqtt_client.py

@@ -5,11 +5,25 @@ from .models import Recording
 from app import db, app
 
 class MqttClient:
-    def __init__(self):
-        self.mqtt = Mqtt()
-        self.initialized = False
+    class __MqttClient:
+        def __init__(self):
+            self.mqtt = Mqtt()
+            self.initialized = False
+        def __str__(self):
+            return repr(self)
 
 
+    instance = None
+
+
+    def __init__(self):
+        if not MqttClient.instance:
+            MqttClient.instance = MqttClient.__MqttClient()
+
+
+    def __getattr__(self, name):
+        return getattr(self.instance, name)
+
     # Mqtt setup
     def setup(self, app):
         if not self.initialized: