Rework MQTT config merging and adding defaults

homeassistant/components/mqtt/__init__.py

@@ -209,14 +209,16 @@ async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
     # Fetch configuration and add default values
     hass_config = await conf_util.async_hass_config_yaml(hass)
     mqtt_yaml = PLATFORM_CONFIG_SCHEMA_BASE(hass_config.get(DOMAIN, {}))
+    client = MQTT(hass, entry, conf)
     if DOMAIN in hass.data:
         mqtt_data = get_mqtt_data(hass)
         mqtt_data.config = mqtt_yaml
+        mqtt_data.client = client
     else:
-        hass.data[DATA_MQTT] = mqtt_data = MqttData(config=mqtt_yaml)
+        hass.data[DATA_MQTT] = mqtt_data = MqttData(config=mqtt_yaml, client=client)
+    client.start(mqtt_data)
 
     await async_create_certificate_temp_files(hass, dict(entry.data))
-    mqtt_data.client = MQTT(hass, entry, conf)
     # Restore saved subscriptions
     if mqtt_data.subscriptions_to_restore:
         mqtt_data.client.async_restore_tracked_subscriptions(
@@ -282,7 +284,7 @@ async def async_publish_service(call: ServiceCall) -> None:
                 )
                 return
 
-        assert mqtt_data.client is not None and msg_topic is not None
+        assert msg_topic is not None
         await mqtt_data.client.async_publish(msg_topic, payload, qos, retain)
 
     hass.services.async_register(
@@ -518,7 +520,6 @@ def unsubscribe() -> None:
 def is_connected(hass: HomeAssistant) -> bool:
     """Return if MQTT client is connected."""
     mqtt_data = get_mqtt_data(hass)
-    assert mqtt_data.client is not None
     return mqtt_data.client.connected
 
 
@@ -536,7 +537,6 @@ async def async_remove_config_entry_device(
 async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
     """Unload MQTT dump and publish service when the config entry is unloaded."""
     mqtt_data = get_mqtt_data(hass)
-    assert mqtt_data.client is not None
     mqtt_client = mqtt_data.client
 
     # Unload publish and dump services.

homeassistant/components/mqtt/client.py

@@ -69,6 +69,7 @@
 from .models import (
     AsyncMessageCallbackType,
     MessageCallbackType,
+    MqttData,
     PublishMessage,
     PublishPayloadType,
     ReceiveMessage,
@@ -116,7 +117,6 @@ async def async_publish(
             f"Cannot publish to topic '{topic}', MQTT is not enabled"
         )
     mqtt_data = get_mqtt_data(hass)
-    assert mqtt_data.client is not None
     outgoing_payload = payload
     if not isinstance(payload, bytes):
         if not encoding:
@@ -167,7 +167,6 @@ async def async_subscribe(
             f"Cannot subscribe to topic '{topic}', MQTT is not enabled"
         )
     mqtt_data = get_mqtt_data(hass)
-    assert mqtt_data.client is not None
     # Support for a deprecated callback type was removed with HA core 2023.3.0
     # The signature validation code can be removed from HA core 2023.5.0
     non_default = 0
@@ -377,21 +376,18 @@ async def async_cleanup(self) -> None:
 class MQTT:
     """Home Assistant MQTT client."""
 
-    _mqttc: mqtt.Client
+    _mqttc: mqtt.Client = None  # type: ignore[assignment]
     _last_subscribe: float
+    _mqtt_data: MqttData
 
     def __init__(
-        self,
-        hass: HomeAssistant,
-        config_entry: ConfigEntry,
-        conf: ConfigType,
+        self, hass: HomeAssistant, config_entry: ConfigEntry, conf: ConfigType
     ) -> None:
         """Initialize Home Assistant MQTT client."""
-        self._mqtt_data = get_mqtt_data(hass)
-
         self.hass = hass
         self.config_entry = config_entry
         self.conf = conf
+
         self._simple_subscriptions: dict[str, list[Subscription]] = {}
         self._wildcard_subscriptions: list[Subscription] = []
         self.connected = False
@@ -417,8 +413,6 @@ def ha_started(_: Event) -> None:
 
             self.hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STARTED, ha_started)
 
-        self.init_client()
-
         async def async_stop_mqtt(_event: Event) -> None:
             """Stop MQTT component."""
             await self.async_disconnect()
@@ -427,6 +421,14 @@ async def async_stop_mqtt(_event: Event) -> None:
             hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, async_stop_mqtt)
         )
 
+    def start(
+        self,
+        mqtt_data: MqttData,
+    ) -> None:
+        """Start Home Assistant MQTT client."""
+        self._mqtt_data = mqtt_data
+        self.init_client()
+
     @property
     def subscriptions(self) -> list[Subscription]:
         """Return the tracked subscriptions."""

homeassistant/components/mqtt/mixins.py

@@ -562,7 +562,6 @@ async def async_will_remove_from_hass(self) -> None:
     def available(self) -> bool:
         """Return if the device is available."""
         mqtt_data = get_mqtt_data(self.hass)
-        assert mqtt_data.client is not None
         client = mqtt_data.client
         if not client.connected and not self.hass.is_stopping:
             return False

homeassistant/components/mqtt/models.py

@@ -288,8 +288,8 @@ def write_state_request(self, entity: Entity) -> None:
 class MqttData:
     """Keep the MQTT entry data."""
 
+    client: MQTT
     config: ConfigType
-    client: MQTT | None = None
     debug_info_entities: dict[str, EntityDebugInfo] = field(default_factory=dict)
     debug_info_triggers: dict[tuple[str, str], TriggerDebugInfo] = field(
         default_factory=dict