Watch pre-defined lm-sensors values and post them to MQTT topics.

The following environment variables are expected:

• LOG_LEVEL Log level for the application. Possible values are debug, info, warning, error, critical, notset. Defaults to info.
• MQTT_HOST Name of the MQTT host
• MQTT_TOPIC Prefix for the MQTT topic
• CE_SOURCE Source attribute for the Cloud Events message (see CloudEvents and CloudEvents attributes), defaults to https://github.com/penguineer/SensorsReport.
• CE_TYPE Type attribute for the Cloud Events message, defaults to io.github.penguineer.SensorsReport.measurement.
• CE_MQTT_TOPIC Topic for the Cloud Events message. If not specified, /CloudEvent will be added to the sensor's generated topic. Please note that this will lead to a burst of messages on a single topic!
• SENSORS expects a JSON sensor configuration in the following form:

{
  "sensors": [
    {
      "label": "<sensor feature label>",
      "topic": "<feature mqtt topic (added to prefix)>",
      "lm-sensors": {
        "chip": "<chip name>",
        "feature": "<feature name>"
      }
    },
    {
      "label": "<sensor feature label>",
      "topic": "<feature mqtt topic (added to prefix)>",
      "file": {
        "path": "<file path to read>"
      }
    }
  ]
}

In the above example, anything listed as <...> is meant to be replaced by a value described by the label with the brackets, e.g. <chip name> is written as coretemp-isa-0000 without the brackets. The top "sensors" object may seem redundant, but allows for future expansion of the configuration.

The following data providers are available:

• lm-sensors: Reads the value from the lm-sensors chip and feature name.
  • chip: The name of the chip as shown by sensors -l
  • feature: The name of the feature as shown by sensors -l
• file: Reads the value from a file.
  • path: The path to the file to read. The file must contain a single line with the value to be read. A final newline will be stripped.

The report is emitted as a CloudEvents message. The following attributes are set:

{
  "specversion": "1.0",
  "event_id": "<UUID>",
  "source": "https://github.com/penguineer/SensorsReport",
  "event_type": "io.github.penguineer.SensorsReport.measurement",
  "time": "<ISO 8601 timestamp>",
  "subject": "<The sensor's topic>",
  "datacontenttype": "application/json",
  "data": {
    "topic": "<The sensor's topic>",
    "label": "<The sensor's label, if configured>",
    "value": "<Measured sensor value>"
  }
}

The sensor's topic is mirrored to the subject attribute to allow out-of-band filtering of the messages with intermediary handlers.

With the configuration stored in a file .env, the tool can be started as follows:

docker run --rm \
  --env-file .env \
  mrtux/sensors-report:latest

Please replace latest with the version you want to run. The latest version is not guaranteed to be stable.

Alternatively there is a docker compose set up to build and run from the repository. For production use pre-built docker images are recommended.

Contributions are welcome and should be made via PR.

Please note that for any more complicated use cases a fully fledged monitoring system might be more appropriate.

MIT © 2021-2025 Stefan Haun and contributors