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Integration file structure

Each integration is stored inside a directory named after the integration domain. The domain is a short name consisting of characters and underscores. This domain has to be unique and cannot be changed. Example of the domain for the mobile app integration: mobile_app. So all files for this integration are in the folder mobile_app/.

The bare minimum content of this folder looks like this:

  • manifest.json: The manifest file describes the integration and its dependencies. More info
  • __init__.py: The component file. If the integration only offers a platform, you can keep this file limited to a docstring introducing the integration """The Mobile App integration.""".

Integrating devices - light.py, switch.py etc​

If your integration is going to integrate one or more devices, you will need to do this by creating a platform that interacts with an entity integration. For example, if you want to represent a light device inside Home Assistant, you will create light.py, which will contain a light platform for the light integration.

Integrating service actions - services.yaml​

If your integration is going to register service actions, it will need to provide a description of the available actions. The description is stored in services.yaml. More information about services.yaml.

Data update coordinator - coordinator.py​

There are multiple ways for your integration to receive data, including push or poll. Commonly integrations will fetch data with a single coordinated poll across all entities, which requires the use of a DataUpdateCoordinator. If you want to use one, and you choose to create a subclass of it, it is recommended to define the coordinator class in coordinator.py. More information about DataUpdateCoordinator.

Where Home Assistant looks for integrations​

Home Assistant will look for an integration when it sees the domain referenced in the config file (i.e. mobile_app:) or if it is a dependency of another integration. Home Assistant will look at the following locations:

  • <config directory>/custom_components/<domain>
  • homeassistant/components/<domain> (built-in integrations)

You can override a built-in integration by having an integration with the same domain in your <config directory>/custom_components folder. The manifest.json file requires a version tag when you override a core integration. An overridden core integration can be identified by a specific icon in the upper right corner of the integration box in the overview Open your Home Assistant instance and show your integrations. Note that overriding built-in integrations is not recommended as you will no longer get updates. It is recommended to pick a unique name.