Provide an option to select MQTT unique_id generator (#2701)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
Co-authored-by: Oxan van Leeuwen <oxan@oxanvanleeuwen.nl>

esphome/components/mqtt/__init__.py

@@ -14,6 +14,7 @@ from esphome.const import (
     CONF_DISCOVERY,
     CONF_DISCOVERY_PREFIX,
     CONF_DISCOVERY_RETAIN,
+    CONF_DISCOVERY_UNIQUE_ID_GENERATOR,
     CONF_ID,
     CONF_KEEPALIVE,
     CONF_LEVEL,
@@ -95,6 +96,12 @@ MQTTTextSensor = mqtt_ns.class_("MQTTTextSensor", MQTTComponent)
 MQTTNumberComponent = mqtt_ns.class_("MQTTNumberComponent", MQTTComponent)
 MQTTSelectComponent = mqtt_ns.class_("MQTTSelectComponent", MQTTComponent)
 
+MQTTDiscoveryUniqueIdGenerator = mqtt_ns.enum("MQTTDiscoveryUniqueIdGenerator")
+MQTT_DISCOVERY_UNIQUE_ID_GENERATOR_OPTIONS = {
+    "legacy": MQTTDiscoveryUniqueIdGenerator.MQTT_LEGACY_UNIQUE_ID_GENERATOR,
+    "mac": MQTTDiscoveryUniqueIdGenerator.MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR,
+}
+
 
 def validate_config(value):
     # Populate default fields
@@ -153,6 +160,9 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(
                 CONF_DISCOVERY_PREFIX, default="homeassistant"
             ): cv.publish_topic,
+            cv.Optional(CONF_DISCOVERY_UNIQUE_ID_GENERATOR, default="legacy"): cv.enum(
+                MQTT_DISCOVERY_UNIQUE_ID_GENERATOR_OPTIONS
+            ),
             cv.Optional(CONF_USE_ABBREVIATIONS, default=True): cv.boolean,
             cv.Optional(CONF_BIRTH_MESSAGE): MQTT_MESSAGE_SCHEMA,
             cv.Optional(CONF_WILL_MESSAGE): MQTT_MESSAGE_SCHEMA,
@@ -231,13 +241,22 @@ async def to_code(config):
     discovery = config[CONF_DISCOVERY]
     discovery_retain = config[CONF_DISCOVERY_RETAIN]
     discovery_prefix = config[CONF_DISCOVERY_PREFIX]
+    discovery_unique_id_generator = config[CONF_DISCOVERY_UNIQUE_ID_GENERATOR]
 
     if not discovery:
         cg.add(var.disable_discovery())
     elif discovery == "CLEAN":
-        cg.add(var.set_discovery_info(discovery_prefix, discovery_retain, True))
+        cg.add(
+            var.set_discovery_info(
+                discovery_prefix, discovery_unique_id_generator, discovery_retain, True
+            )
+        )
     elif CONF_DISCOVERY_RETAIN in config or CONF_DISCOVERY_PREFIX in config:
-        cg.add(var.set_discovery_info(discovery_prefix, discovery_retain))
+        cg.add(
+            var.set_discovery_info(
+                discovery_prefix, discovery_unique_id_generator, discovery_retain
+            )
+        )
 
     cg.add(var.set_topic_prefix(config[CONF_TOPIC_PREFIX]))
 

esphome/components/mqtt/mqtt_client.cpp

@@ -535,8 +535,10 @@ void MQTTClientComponent::set_birth_message(MQTTMessage &&message) {
 
 void MQTTClientComponent::set_shutdown_message(MQTTMessage &&message) { this->shutdown_message_ = std::move(message); }
 
-void MQTTClientComponent::set_discovery_info(std::string &&prefix, bool retain, bool clean) {
+void MQTTClientComponent::set_discovery_info(std::string &&prefix, MQTTDiscoveryUniqueIdGenerator unique_id_generator,
+                                             bool retain, bool clean) {
   this->discovery_info_.prefix = std::move(prefix);
+  this->discovery_info_.unique_id_generator = unique_id_generator;
   this->discovery_info_.retain = retain;
   this->discovery_info_.clean = clean;
 }

esphome/components/mqtt/mqtt_client.h

@@ -55,6 +55,12 @@ struct Availability {
   std::string payload_not_available;
 };
 
+/// available discovery unique_id generators
+enum MQTTDiscoveryUniqueIdGenerator {
+  MQTT_LEGACY_UNIQUE_ID_GENERATOR = 0,
+  MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR,
+};
+
 /** Internal struct for MQTT Home Assistant discovery
  *
  * See <a href="https://www.home-assistant.io/docs/mqtt/discovery/">MQTT Discovery</a>.
@@ -63,6 +69,7 @@ struct MQTTDiscoveryInfo {
   std::string prefix;  ///< The Home Assistant discovery prefix. Empty means disabled.
   bool retain;         ///< Whether to retain discovery messages.
   bool clean;
+  MQTTDiscoveryUniqueIdGenerator unique_id_generator;
 };
 
 enum MQTTClientState {
@@ -98,9 +105,11 @@ class MQTTClientComponent : public Component {
    *
    * See <a href="https://www.home-assistant.io/docs/mqtt/discovery/">MQTT Discovery</a>.
    * @param prefix The Home Assistant discovery prefix.
+   * @param unique_id_generator Controls how UniqueId is generated.
    * @param retain Whether to retain discovery messages.
    */
-  void set_discovery_info(std::string &&prefix, bool retain, bool clean = false);
+  void set_discovery_info(std::string &&prefix, MQTTDiscoveryUniqueIdGenerator unique_id_generator, bool retain,
+                          bool clean = false);
   /// Get Home Assistant discovery info.
   const MQTTDiscoveryInfo &get_discovery_info() const;
   /// Globally disable Home Assistant discovery.

esphome/components/mqtt/mqtt_component.cpp

@@ -113,11 +113,19 @@ bool MQTTComponent::send_discovery_() {
         std::string unique_id = this->unique_id();
         if (!unique_id.empty()) {
           root[MQTT_UNIQUE_ID] = unique_id;
+        } else {
+          const MQTTDiscoveryInfo &discovery_info = global_mqtt_client->get_discovery_info();
+          if (discovery_info.unique_id_generator == MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR) {
+            char friendly_name_hash[9];
+            sprintf(friendly_name_hash, "%08x", fnv1_hash(this->friendly_name()));
+            friendly_name_hash[8] = 0;  // ensure the hash-string ends with null
+            root[MQTT_UNIQUE_ID] = get_mac_address() + "-" + this->component_type() + "-" + friendly_name_hash;
           } else {
             // default to almost-unique ID. It's a hack but the only way to get that
             // gorgeous device registry view.
             root[MQTT_UNIQUE_ID] = "ESP" + this->component_type() + this->get_default_object_id_();
           }
+        }
 
         JsonObject &device_info = root.createNestedObject(MQTT_DEVICE);
         device_info[MQTT_DEVICE_IDENTIFIERS] = get_mac_address();

esphome/const.py

@@ -167,6 +167,7 @@ CONF_DISABLED_BY_DEFAULT = "disabled_by_default"
 CONF_DISCOVERY = "discovery"
 CONF_DISCOVERY_PREFIX = "discovery_prefix"
 CONF_DISCOVERY_RETAIN = "discovery_retain"
+CONF_DISCOVERY_UNIQUE_ID_GENERATOR = "discovery_unique_id_generator"
 CONF_DISTANCE = "distance"
 CONF_DITHER = "dither"
 CONF_DIV_RATIO = "div_ratio"

tests/test1.yaml

@@ -98,6 +98,7 @@ mqtt:
   discovery: True
   discovery_retain: False
   discovery_prefix: discovery
+  discovery_unique_id_generator: legacy
   topic_prefix: helloworld
   log_topic:
     topic: helloworld/hi