Option to reuse the MQTT configuration of the plugin if not provided on the backend

platypush/backend/mqtt.py

@@ -39,7 +39,9 @@ class MqttBackend(Backend):
                  client_id: Optional[str] = None, listeners=None,
                  *args, **kwargs):
         """
-        :param host: MQTT broker host
+        :param host: MQTT broker host. If no host configuration is specified then
+            the backend will use the host configuration specified on the ``mqtt``
+            plugin if it's available.
         :param port: MQTT broker port (default: 1883)
         :param topic: Topic to read messages from (default: ``platypush_bus_mq/<device_id>``)
         :param subscribe_default_topic: Whether the backend should subscribe the default topic (default:
@@ -83,22 +85,39 @@ class MqttBackend(Backend):
 
         super().__init__(*args, **kwargs)
 
+        if host:
             self.host = host
             self.port = port
-        self.topic = '{}/{}'.format(topic, self.device_id)
-        self.subscribe_default_topic = subscribe_default_topic
-        self.username = username
-        self.password = password
-        self.client_id = client_id or Config.get('device_id')
-        self._client = None
-        self._listeners = []
-
             self.tls_cafile = self._expandpath(tls_cafile) if tls_cafile else None
             self.tls_certfile = self._expandpath(tls_certfile) if tls_certfile else None
             self.tls_keyfile = self._expandpath(tls_keyfile) if tls_keyfile else None
             self.tls_version = MQTTPlugin.get_tls_version(tls_version)
             self.tls_ciphers = tls_ciphers
             self.tls_insecure = tls_insecure
+            self.username = username
+            self.password = password
+            self.client_id = client_id or Config.get('device_id')
+        else:
+            client = get_plugin('mqtt')
+            assert client.host, 'No host specified on backend.mqtt nor mqtt configuration'
+
+            self.host = client.host
+            self.port = client.port
+            self.tls_cafile = client.tls_cafile
+            self.tls_certfile = client.tls_certfile
+            self.tls_keyfile = client.tls_keyfile
+            self.tls_version = client.tls_version
+            self.tls_ciphers = client.tls_ciphers
+            self.tls_insecure = client.tls_insecure
+            self.username = client.username
+            self.password = client.password
+            self.client_id = client_id or client.client_id
+
+        self.topic = '{}/{}'.format(topic, self.device_id)
+        self.subscribe_default_topic = subscribe_default_topic
+        self._client = None
+        self._listeners = []
+
         self.listeners_conf = listeners or []
 
     def send_message(self, msg, topic: Optional[str] = None, **kwargs):

platypush/plugins/mqtt.py

@@ -69,15 +69,9 @@ class MqttPlugin(Plugin):
         self.username = username
         self.password = password
         self.client_id = client_id or Config.get('device_id')
-        self.tls_cafile = os.path.abspath(os.path.expanduser(tls_cafile)) \
+        self.tls_cafile = self._expandpath(tls_cafile) if tls_cafile else None
-            if tls_cafile else None
+        self.tls_certfile = self._expandpath(tls_certfile) if tls_certfile else None
-
+        self.tls_keyfile = self._expandpath(tls_keyfile) if tls_keyfile else None
-        self.tls_certfile = os.path.abspath(os.path.expanduser(tls_certfile)) \
-            if tls_certfile else None
-
-        self.tls_keyfile = os.path.abspath(os.path.expanduser(tls_keyfile)) \
-            if tls_keyfile else None
-
         self.tls_version = self.get_tls_version(tls_version)
         self.tls_insecure = tls_insecure
         self.tls_ciphers = tls_ciphers
@@ -100,14 +94,17 @@ class MqttPlugin(Plugin):
 
         assert 'Unrecognized TLS version: {}'.format(version)
 
+    @staticmethod
+    def _expandpath(path: Optional[str] = None) -> Optional[str]:
+        return os.path.abspath(os.path.expanduser(path)) if path else None
+
     @action
     def publish(self, topic: str, msg: Any, host: Optional[str] = None, port: int = 1883,
                 reply_topic: Optional[str] = None, timeout: int = 60,
                 tls_cafile: Optional[str] = None, tls_certfile: Optional[str] = None,
                 tls_keyfile: Optional[str] = None, tls_version: Optional[str] = None,
                 tls_ciphers: Optional[str] = None, tls_insecure: Optional[bool] = None,
-                username: Optional[str] = None, password: Optional[str] = None,
+                username: Optional[str] = None, password: Optional[str] = None):
-                client_id: Optional[str] = None):
         """
         Sends a message to a topic.
 
@@ -131,15 +128,15 @@ class MqttPlugin(Plugin):
             required, specify it here (default: None).
         :param username: Specify it if the MQTT server requires authentication (default: None).
         :param password: Specify it if the MQTT server requires authentication (default: None).
-        :param client_id: Override the default client_id (default: None).
         """
         from paho.mqtt.client import Client
 
         if not host and not self.host:
             raise RuntimeError('No host specified and no default host configured')
 
-        client_id = client_id or self.client_id
         if not host:
+            host = self.host
+            port = self.port
             tls_cafile = self.tls_cafile
             tls_certfile = self.tls_certfile
             tls_keyfile = self.tls_keyfile
@@ -149,12 +146,15 @@ class MqttPlugin(Plugin):
             username = self.username
             password = self.password
         else:
+            tls_cafile = self._expandpath(tls_cafile)
+            tls_certfile = self._expandpath(tls_certfile)
+            tls_keyfile = self._expandpath(tls_keyfile)
             if tls_version:
                 tls_version = self.get_tls_version(tls_version)
             if tls_insecure is None:
                 tls_insecure = self.tls_insecure
 
-        client = Client(client_id)
+        client = Client()
 
         if username and password:
             client.username_pw_set(username, password)