Home Assistant Home Assistant

Python Scripts

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

Name Description
hass The Home Assistant object. Access is only allowed to call services, set/remove states and fire events. API reference
data The data passed to the Python Script service call.
logger A logger to allow you to log messages: logger.info(), logger.warning(), logger.error(). API reference
time The stdlib time available as limited access.
datetime The stdlib datetime available as limited access.
dt_util The homeassistant.util.dt module.

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.

It is not possible to use Python imports with this integration. If you want to do more advanced scripts, you can take a look at AppDaemon or pyscript

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.yaml: 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()))

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

Running this script show absolutely no output on the screen, but it logs with level info. You must have the Logger enabled at least for level info.

Your configuration.yaml should include something like this.

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.

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

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.

Services

Available services: reload.

Service 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 service data attributes.