ESPHome: Using metadata for improving instant Grafana dashboards

[amotl]

Hi once more,

while working on the support for ESPHome (#67), we found that it offers a nice capability in the spirit that it will publish metadata information about each sensor to the MQTT broker on startup. The corresponding JSON payload(s), as outlined below, are published to the /config topic suffix.

From this metadata information, Kotori would be able to derive relevant information to make the "instant-on" experience more pleasant. For example, by using the full name of the sensor like "name": "EVB-02-BME280 Relative Humidity" and its "unit_of_measurement": "%".

Example:

MQTT topic homeassistant/sensor/evb-ea-ind-02/evb-02-bme280_relative_humidity/config JSON payload:

{
  "device_class": "humidity",
  "unit_of_measurement": "%",
  "state_class": "measurement",
  "name": "EVB-02-BME280 Relative Humidity",
  "state_topic": "evb-ea-ind-02/sensor/evb-02-bme280_relative_humidity/state",
  "availability_topic": "evb-ea-ind-02/status",
  "unique_id": "ESPsensorevb-02-bme280_relative_humidity",
  "device": {
    "identifiers": "c45bbe8d092c",
    "name": "evb-ea-ind-02",
    "sw_version": "esphome v2021.10.3 Nov 20 2021, 20:46:50",
    "model": "esp32dev",
    "manufacturer": "espressif"
  }
}

With kind regards, Andreas.

---

mosquitto_sub -h daq.example.org -t '#' -v

homeassistant/sensor/evb-ea-ind-02/mpu9150_dt/config {"unit_of_measurement":"°","name":"MPU9150_dT","state_topic":"evb-ea-ind-02/sensor/mpu9150_dt/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_dt","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_compass_x/config {"unit_of_measurement":"°","name":"MPU9150_Compass_X","state_topic":"evb-ea-ind-02/sensor/mpu9150_compass_x/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_compass_x","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_compass_y/config {"unit_of_measurement":"°","name":"MPU9150_Compass_Y","state_topic":"evb-ea-ind-02/sensor/mpu9150_compass_y/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_compass_y","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_compass_z/config {"unit_of_measurement":"°","name":"MPU9150_Compass_Z","state_topic":"evb-ea-ind-02/sensor/mpu9150_compass_z/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_compass_z","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_gyro_x/config {"unit_of_measurement":"°","name":"MPU9150_Gyro_X","state_topic":"evb-ea-ind-02/sensor/mpu9150_gyro_x/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_gyro_x","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_gyro_y/config {"unit_of_measurement":"°","name":"MPU9150_Gyro_Y","state_topic":"evb-ea-ind-02/sensor/mpu9150_gyro_y/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_gyro_y","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_gyro_z/config {"unit_of_measurement":"°","name":"MPU9150_Gyro_Z","state_topic":"evb-ea-ind-02/sensor/mpu9150_gyro_z/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_gyro_z","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_acceleration_x/config {"unit_of_measurement":"°","name":"MPU9150_Acceleration_X","state_topic":"evb-ea-ind-02/sensor/mpu9150_acceleration_x/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_acceleration_x","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_acceleration_y/config {"unit_of_measurement":"°","name":"MPU9150_Acceleration_Y","state_topic":"evb-ea-ind-02/sensor/mpu9150_acceleration_y/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_acceleration_y","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/mpu9150_acceleration_z/config {"unit_of_measurement":"°","name":"MPU9150_Acceleration_Z","state_topic":"evb-ea-ind-02/sensor/mpu9150_acceleration_z/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensormpu9150_acceleration_z","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-bme280_temperature/config {"device_class":"temperature","unit_of_measurement":"°C","state_class":"measurement","name":"EVB-02-BME280 Temperature","state_topic":"evb-ea-ind-02/sensor/evb-02-bme280_temperature/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-bme280_temperature","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-bme280_pressure/config {"device_class":"pressure","unit_of_measurement":"hPa","state_class":"measurement","name":"EVB-02-BME280 Pressure","state_topic":"evb-ea-ind-02/sensor/evb-02-bme280_pressure/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-bme280_pressure","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-bme280_relative_humidity/config {"device_class":"humidity","unit_of_measurement":"%","state_class":"measurement","name":"EVB-02-BME280 Relative Humidity","state_topic":"evb-ea-ind-02/sensor/evb-02-bme280_relative_humidity/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-bme280_relative_humidity","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-altitude/config {"unit_of_measurement":"m","name":"EVB-02-Altitude","icon":"mdi:signal","state_topic":"evb-ea-ind-02/sensor/evb-02-altitude/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-altitude","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/hx711_value/config {"unit_of_measurement":"kg","state_class":"measurement","name":"HX711 Value","icon":"mdi:scale","state_topic":"evb-ea-ind-02/sensor/hx711_value/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorhx711_value","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-absolute_humidity/config {"unit_of_measurement":"g/m³","name":"EVB-02-Absolute Humidity","icon":"mdi:water","state_topic":"evb-ea-ind-02/sensor/evb-02-absolute_humidity/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-absolute_humidity","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}
homeassistant/sensor/evb-ea-ind-02/evb-02-dew_point/config {"unit_of_measurement":"°C","name":"EVB-02-Dew Point","icon":"mdi:thermometer-alert","state_topic":"evb-ea-ind-02/sensor/evb-02-dew_point/state","availability_topic":"evb-ea-ind-02/status","unique_id":"ESPsensorevb-02-dew_point","device":{"identifiers":"c45bbe8d092c","name":"evb-ea-ind-02","sw_version":"esphome v2021.10.3 Nov 20 2021, 20:46:50","model":"esp32dev","manufacturer":"espressif"}}

[amotl]

We just discovered that this style and mechanism of sensor announcements to the MQTT bus is actually called »MQTT discovery«, as defined by Home Assistant at [1]. On behalf of a quick research, we also discovered corresponding generic implementations for C++/Arduino [2], and Python [3].

[1] https://www.home-assistant.io/docs/mqtt/discovery/ [2] https://github.com/plapointe6/HAMqttDevice [3] https://pypi.org/project/homeassistant-mqtt-binding/