Support templating MQTT triggers (#45614)

* Add support for limited templates (no HASS access)

* Pass variables to automation triggers

* Support templates in MQTT triggers

* Spelling

* Handle trigger referenced by variables

* Raise on unsupported function in limited templates

* Validate MQTT trigger schema in MQTT device trigger

* Add trigger_variables to automation config schema

* Don't print stacktrace when setting up trigger throws

* Make pylint happy

* Add trigger_variables to variables

* Add debug prints, document limited template

* Add tests

* Validate MQTT trigger topic early when possible

* Improve valid_subscribe_topic_template

homeassistant/components/automation/__init__.py

@@ -60,6 +60,7 @@ from .const import (
     CONF_ACTION,
     CONF_INITIAL_STATE,
     CONF_TRIGGER,
+    CONF_TRIGGER_VARIABLES,
     DEFAULT_INITIAL_STATE,
     DOMAIN,
     LOGGER,
@@ -221,6 +222,7 @@ class AutomationEntity(ToggleEntity, RestoreEntity):
         action_script,
         initial_state,
         variables,
+        trigger_variables,
     ):
         """Initialize an automation entity."""
         self._id = automation_id
@@ -236,6 +238,7 @@ class AutomationEntity(ToggleEntity, RestoreEntity):
         self._referenced_devices: Optional[Set[str]] = None
         self._logger = LOGGER
         self._variables: ScriptVariables = variables
+        self._trigger_variables: ScriptVariables = trigger_variables
 
     @property
     def name(self):
@@ -471,6 +474,16 @@ class AutomationEntity(ToggleEntity, RestoreEntity):
         def log_cb(level, msg, **kwargs):
             self._logger.log(level, "%s %s", msg, self._name, **kwargs)
 
+        variables = None
+        if self._trigger_variables:
+            try:
+                variables = self._trigger_variables.async_render(
+                    cast(HomeAssistant, self.hass), None, limited=True
+                )
+            except template.TemplateError as err:
+                self._logger.error("Error rendering trigger variables: %s", err)
+                return None
+
         return await async_initialize_triggers(
             cast(HomeAssistant, self.hass),
             self._trigger_config,
@@ -479,6 +492,7 @@ class AutomationEntity(ToggleEntity, RestoreEntity):
             self._name,
             log_cb,
             home_assistant_start,
+            variables,
         )
 
     @property
@@ -556,6 +570,18 @@ async def _async_process_config(
             else:
                 cond_func = None
 
+            # Add trigger variables to variables
+            variables = None
+            if CONF_TRIGGER_VARIABLES in config_block:
+                variables = ScriptVariables(
+                    dict(config_block[CONF_TRIGGER_VARIABLES].as_dict())
+                )
+            if CONF_VARIABLES in config_block:
+                if variables:
+                    variables.variables.update(config_block[CONF_VARIABLES].as_dict())
+                else:
+                    variables = config_block[CONF_VARIABLES]
+
             entity = AutomationEntity(
                 automation_id,
                 name,
@@ -563,7 +589,8 @@ async def _async_process_config(
                 cond_func,
                 action_script,
                 initial_state,
-                config_block.get(CONF_VARIABLES),
+                variables,
+                config_block.get(CONF_TRIGGER_VARIABLES),
             )
 
             entities.append(entity)

homeassistant/components/automation/config.py

@@ -21,6 +21,7 @@ from .const import (
     CONF_HIDE_ENTITY,
     CONF_INITIAL_STATE,
     CONF_TRIGGER,
+    CONF_TRIGGER_VARIABLES,
     DOMAIN,
 )
 from .helpers import async_get_blueprints
@@ -43,6 +44,7 @@ PLATFORM_SCHEMA = vol.All(
             vol.Required(CONF_TRIGGER): cv.TRIGGER_SCHEMA,
             vol.Optional(CONF_CONDITION): _CONDITION_SCHEMA,
             vol.Optional(CONF_VARIABLES): cv.SCRIPT_VARIABLES_SCHEMA,
+            vol.Optional(CONF_TRIGGER_VARIABLES): cv.SCRIPT_VARIABLES_SCHEMA,
             vol.Required(CONF_ACTION): cv.SCRIPT_SCHEMA,
         },
         script.SCRIPT_MODE_SINGLE,

homeassistant/components/automation/const.py

@@ -3,6 +3,7 @@ import logging
 
 CONF_ACTION = "action"
 CONF_TRIGGER = "trigger"
+CONF_TRIGGER_VARIABLES = "trigger_variables"
 DOMAIN = "automation"
 
 CONF_DESCRIPTION = "description"