Python Scripts

This integration allows you to write Python scripts that are exposed as actions in Home Assistant. Each Python file created in the <config>/python_scripts/ folder will be exposed as an action. The content is not cached so you can easily develop: edit file, save changes, perform action. The scripts are run in a sandboxed environment. The following variables are available in the sandbox:

Other imports like min, max are available as builtins. See the python_script source code for up-to-date information on the available objects inside the script.

Writing your first script, reading input and logging the activity

This is a simplified example that does no real work. It is created as a first step, to help with:

• Demonstrating how to setup the script
• How to process the input data
• How to log the script activity
• How to troubleshoot / manually call the script.

Start by enabling the Python Scripts integration and create the first script.

• Add to configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more]: python_script:
• Create the folder <config>/python_scripts
• Create a file <config>/python_scripts/hello_world.py in the folder and give it this content:

# `data` is available as builtin and is a dictionary with the input data.
name = data.get("name", "world")
# `logger` and `time` are available as builtin without the need of explicit import.
logger.info("Hello {} at {}".format(name, time.time()))

• Start Home Assistant to reload the script configuration.
• Call your new python_script.hello_world action (with parameters) from the Actions, using the YAML mode.

action: python_script.hello_world
data:
  name: "Input-Text"

logger:
  default: info

Triggering events

The following example shows how to trigger a custom event over the hass.bus.

This example uses the hello_world.py from the previous example. Edit the file adding the code listed below to the end of the file. There is no need to reload the configuration or restart Home Assistant.

hass.bus.fire("hello_world_event", {"wow": "from a Python script!"})

This script doesn’t output anything. However, you can view the events being fired in the Developer tools.

From a separate browser window or tab, go to Developer Tools -> Events and at Listen to events type hello_world_event and then press Start listening. You should see something like this:

event_type: hello_world_event
data:
  wow: from a Python script!
origin: LOCAL
time_fired: "2022-09-19T16:15:39.613378+00:00"
context:
  id: 01GDB8H9JXJ1N23Q62SHX6PTBK
  parent_id: null
  user_id: null

Calling services

The following example shows how to call a service from python_script. This script takes two parameters: entity_id (required), rgb_color (optional) and calls light.turn_on service by setting the brightness value to 255.

# turn_on_light.py
entity_id = data.get("entity_id")
rgb_color = data.get("rgb_color", [255, 255, 255])
if entity_id is not None:
    service_data = {"entity_id": entity_id, "rgb_color": rgb_color, "brightness": 255}
    hass.services.call("light", "turn_on", service_data, False)

The above python_script can be called using the following YAML as an input.

- action: python_script.turn_on_light
  target:
    entity_id: light.bedroom
  data:
    rgb_color: [255, 0, 0]

Services can also respond with data. Retrieve this data in your Python script by setting the blocking and return_response arguments of the hass.services.call function to True. The example below retrieves the weather forecast and assigns it to the current_forecast variable:

# get_forecast.py
service_data = {"type": "daily", "entity_id": ["weather.YOUR_HOME", "weather.YOUR_SCHOOL"]}
current_forecast = hass.services.call("weather", "get_forecasts", service_data, blocking=True, return_response=True)

Returning data

Python script itself can respond with data. Just add items to the output variable in your python_script and the whole dictionary will be returned. These can be used in automations to act upon the command results using response_variable.

# hello_world.py
output["hello"] = f"hello {data.get('name', 'world')}"

The above python_script can be called using the following YAML and return a result to later steps.

- action: python_script.hello_world
  response_variable: python_script_output
- action: notify.mobile_app_iphone
  data:
    message: "{{ python_script_output['hello'] }}"

Documenting your Python scripts

You can add names and descriptions for your Python scripts that will be shown in the frontend. To do so, simply create a services.yaml file in your <config>/python_scripts folder. Using the above Python script as an example, the services.yaml file would look like:

# services.yaml
turn_on_light:
  name: Turn on light
  description: Turn on a specific light and set its color.
  fields:
    entity_id:
      description: The light that will be turned on.
      example: light.bedroom
    rgb_color:
      description: The color to which the light will be set.
      example: [255, 0, 0]

For more examples, visit the Scripts section in our forum.

Actions

Available actions: reload.

Action python_script.reload

Reload all available python_scripts from the <config>/python_scripts folder, as a quicker alternative to restarting Home Assistant.

Use this when creating a new Python script, or after updating the <config>/python_scripts/services.yaml file.

You don’t have to call this service when you change an existing Python script.

This service takes no data attributes.