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Script Sensors

Go Hass Agent supports utilising scripts to create sensors. In this way, you can extend the sensors presented to Home Assistant by the agent. Note that as the agent is a “mobile app” in Home Assistant, any script sensors will be associated with the Go Hass Agent device in Home Assistant.

Each script run by the agent can create one or more sensors and each script can run on its own schedule, specified using a Cron-like syntax.

Requirements

Scripts need to be put in $HOME/.config/com.github.joshuar.go-hass-agent/scripts/. You can use symlinks.
Script files need to be executable by the user running Go Hass Agent.
Scripts need to run without any user interaction.
Scripts need to output either valid JSON, YAML or TOML. See Output Format for details.

Output Format

All scripts should produce output that is either valid JSON, YAML or TOML. Scripts do not need to use the same format; you can have one script that produces JSON and another that produces TOML. All scripts will need to output the following fields:

A schedule field containing a cron-formatted schedule.
A sensors field containing a list of sensors.

Sensors themselves need to be represented by the following fields:

sensor_name: the friendly name of the sensor in Home Assistant (e.g., My Script Sensor).
sensor_icon: a Material Design Icon representing the current state. It can be changed dynamically based on the current state or remain constant. Format is mdi:icon_name.
sensor_state: the current value of the sensor. For numerical states, without the units. Otherwise, a string or boolean (for binary sensors).
- Note: for a binary sensor, do not enclose the true/false in quotes.

The following optional fields can also be specified, which help control the display in Home Assistant.

sensor_units: the units for the state value.
sensor_type: the type of sensor. If this is a binary sensor with a boolean value, set this to “binary”. Else, do not set this field.
sensor_device_class: a Home Assistant Device Class for the sensor, which will dictate how it will be displayed in Home Assistant. There are many, pick an appropriate one (see internal/hass/sensor/deviceClass.go). If setting sensor_device_class, it is likely required to set an appropriate unit in sensor_units as well.
sensor_state_class: the Home Assistant State Class. Either measurement, total or total_increasing.
sensor_attributes: any additional attributes to be displayed with the sensor. Note that the value is required to be valid JSON, regardless of the script output format.

Examples

The following examples show a script that produces two sensors, in different output formats.

JSON

JSON output can be either compressed:

{"schedule":"@every 5s","sensors":[{"sensor_name": "random 1","sensor_icon": "mdi:dice-1","sensor_state":1},{"sensor_name": "random 2","sensor_icon": "mdi:dice-2","sensor_state_class":"measurement","sensor_state":6}]}

Or pretty-printed:

{
  "schedule": "@every 5s",
  "sensors": [
    {
      "sensor_name": "random 1",
      "sensor_icon": "mdi:dice-1",
      "sensor_state": 2
    },
    {
      "sensor_name": "random 2",
      "sensor_icon": "mdi:dice-2",
      "sensor_state_class": "measurement",
      "sensor_state": 6
    }
  ]
}

YAML

schedule: '@every 5s'
sensors:
    - sensor_name: random 1
      sensor_icon: mdi:dice-1
      sensor_state: 8
    - sensor_name: random 2
      sensor_icon: mdi:dice-2
      sensor_state_class: measurement
      sensor_state: 9

TOML

schedule = '@every 5s'

[[sensors]]
sensor_icon = 'mdi:dice-1'
sensor_name = 'random 1'
sensor_state = 3

[[sensors]]
sensor_icon = 'mdi:dice-2'
sensor_name = 'random 2'
sensor_state = 3
sensor_state_class = 'measurement'

For a binary sensor, the output should have sensor_type set to “binary” and the sensor_state as true or false (without quotes). As an example in compressed JSON format:

{"schedule":"@every 10s","sensors":[{"sensor_name":"random 4","sensor_type":"binary","sensor_icon":"mdi:dice-3","sensor_state":false}]}

Schedule

The schedule field is used to specify the schedule or interval on which the script will be run by the agent. Each script is run on its own schedule. All sensors and their values should be returned each time the script is run. The format is documented by the cron Golang package. In most cases, it is presumed that the script needs to be run on some interval of time. In that case, the easiest way to specify that is with the @every <duration> as per the example output such as:

@every 5s: every 5 seconds
@every 1h30m: every 1 and a half hours.

Or a pre-defined schedule:

@hourly.
@daily.
@weekly.
@monthly.
@yearly.

However, more cron formats are supported:

"30 * * * *": every hour on the half hour.
"30 3-6,20-23 * * *": in the range 3-6am, 8-11pm.
"CRON_TZ=Asia/Tokyo 30 04 * * *": at 04:30 Tokyo time every day.

Some schedules, while supported, might not make much sense.

Security

Running scripts can be dangerous, especially if the script does not have robust error-handling or whose origin is untrusted or unknown. Go Hass Agent makes no attempt to do any analysis or sanitisation of script output, other than ensuring the output is a supported format. As such, ensure you trust and understand what the script does and all possible outputs that the script can produce. Scripts are run by the agent and have the permissions of the user running the agent. Script output is sent to your Home Assistant instance.

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