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 foldermobile_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 createlight.py, which will contain a light platform for the light integration.

• More info onavailable entity integrations.
• More info oncreating platforms.

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 inservices.yaml.More information aboutservices.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 aDataUpdateCoordinator.If you want to use one, and you choose to create a subclass of it, it is recommended to define the coordinator class incoordinator.py.More information aboutDataUpdateCoordinator.

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.Themanifest.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 overviewNote that overriding built-in integrations is not recommended as you will no longer get updates. It is recommended to pick a unique name.