home assistant

Home Assistant Integration

system2mqtt supports MQTT Discovery, which allows entities to appear automatically in Home Assistant without any manual configuration.

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Prerequisites

1. The MQTT Integration must be configured in Home Assistant and connected to the same broker that system2mqtt publishes to.
2. MQTT Discovery must be enabled in the MQTT integration (it is on by default).

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Enabling Discovery

Add the following to your s2m.conf:

HA_DISCOVERY=True

Optionally, if you have changed the MQTT discovery prefix in Home Assistant from the default:

HA_DISCOVERY_BASE=homeassistant   # default — match your HA setting

After restarting system2mqtt, entities will appear in Home Assistant under Settings → Devices & Services → MQTT.

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Discovered Entities

For each system being monitored, system2mqtt creates a device in Home Assistant and registers the following entities:

Entity	Type	Unit	Device Class	Icon
<Name> CPU Usage	Sensor	%	power_factor	mdi:cpu-64-bit
<Name> CPU Temperature	Sensor	°C	temperature	mdi:thermometer
<Name> Memory Usage	Sensor	%	power_factor	mdi:memory
<Name> <Disk> Storage	Sensor	%	power_factor	mdi:harddisk
<Name> <Disk> Mount	Binary Sensor	—	connectivity	mdi:harddisk
<Name> Fan Speed	Sensor	%	—	mdi:fan
<Name> <Disk> Temperature	Sensor	°C	temperature	mdi:thermometer

Device information

Each monitored system appears as a single device in Home Assistant:

• Name: S2M <ComputerName> (e.g. S2M Myserver)
• Manufacturer: TeamGREEN Tech
• Model: System2Mqtt
• Identifiers: <computer_name> (lowercase)

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Discovery Topic Format

Discovery messages are published to:

<HA_DISCOVERY_BASE>/<component>/<object_id>/config

For example:

homeassistant/sensor/s2m_myserver_cpu/config
homeassistant/sensor/s2m_myserver_memory/config
homeassistant/binary_sensor/s2m_myserver_disk_sda1/config

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Availability Tracking

All entities use the LWT topic for availability tracking. When the system2mqtt process stops or loses connection, all entities will show as unavailable in Home Assistant.

• Available payload: online
• Unavailable payload: offline
• LWT topic: <MQTT_BASE_TOPIC>/LWT

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Example Discovery Payload

The following is an example discovery payload for a CPU usage sensor:

{
  "name": "MyServer CPU Usage",
  "unique_id": "s2m_myserver_cpu",
  "object_id": "s2m_myserver_cpu",
  "state_topic": "system2mqtt/MyServer/cpu/usage",
  "device": {
    "identifiers": ["myserver"],
    "name": "S2M Myserver",
    "manufacturer": "TeamGREEN Tech",
    "model": "System2Mqtt"
  },
  "availability": {
    "topic": "system2mqtt/MyServer/LWT",
    "payload_available": "online",
    "payload_not_available": "offline"
  },
  "unit_of_measurement": "%",
  "icon": "mdi:cpu-64-bit",
  "device_class": "power_factor"
}

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Removing Entities

Discovery configurations are published with the retain flag. To remove an entity from Home Assistant, publish an empty ("") retained message to its discovery topic:

mosquitto_pub -h 192.168.1.100 -r -t "homeassistant/sensor/s2m_myserver_cpu/config" -m ""

Alternatively, you can remove the device entirely from the Home Assistant MQTT integration UI under Settings → Devices & Services → MQTT → Devices.