developers.home-assistant/docs/api/native-app-integration/setup.md

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Connecting to an instance

When a user first opens the app, they will need to connect to their local instance to authenticate and register the device.

Authenticating the user

The local instance can be discovered if Home Assistant has the zeroconf integration configured by searching for _home-assistant._tcp.local.. If not configured, the user will need to be asked for the local address of their instance.

When the address of the instance is known, the app will ask the user to authenticate via OAuth2 with Home Assistant. Home Assistant uses IndieAuth, which means that to be able to redirect to a url that triggers your app, you need to take some extra steps. Make sure to read the last paragraph of the "Clients" section thoroughly.

Registering the device

This requires Home Assistant 0.90 or later.

Home Assistant has a mobile_app component that allows applications to register themselves and interact with the instance. This is a generic component to handle most common mobile application tasks. This component is extendable with custom interactions if your app needs more types of interactions than are offered by this component.

Once you have tokens to authenticate as a user, it's time to register the app with the mobile app integration in Home Assistant.

Getting ready

First, you must ensure that the mobile_app integration is loaded. There are two ways to do this:

• You can publish a Zeroconf/Bonjour record _hass-mobile-app._tcp.local. to trigger the automatic load of the mobile_app integration. You should wait at least 60 seconds after publishing the record before continuing.
• You can ask the user to add mobile_app to their configuration.yaml and restart Home Assistant. If the user already has default_config in their configuration, then mobile_app will have been already loaded.

You can confirm the mobile_app component has been loaded by checking the components array of the /api/config REST API call. If you continue to device registration and receive a 404 status code, then it most likely hasn't been loaded yet.

Registering the device

To register the device, make an authenticated POST request to /api/mobile_app/registrations. More info on making authenticated requests.

Example payload to send to the registration endpoint:

{
  "device_id": "ABCDEFGH",
  "app_id": "awesome_home",
  "app_name": "Awesome Home",
  "app_version": "1.2.0",
  "device_name": "Robbies iPhone",
  "manufacturer": "Apple, Inc.",
  "model": "iPhone X",
  "os_name": "iOS",
  "os_version": "iOS 10.12",
  "supports_encryption": true,
  "app_data": {
    "push_notification_key": "abcdef"
  }
}

Key	Required	Type	Description
device_id	V	string	A unique identifier for this device. New in Home Assistant 0.104
app_id	V	string	A unique identifier for this app.
app_name	V	string	Name of the mobile app.
app_version	V	string	Version of the mobile app.
device_name	V	string	Name of the device running the app.
manufacturer	V	string	The manufacturer of the device running the app.
model	V	string	The model of the device running the app.
os_name	V	string	The name of the OS running the app.
os_version	V	string	The OS version of the device running the app.
supports_encryption	V	bool	If the app supports encryption. See also the encryption section.
app_data		Dict	App data can be used if the app has a supporting component that extends mobile_app functionality.

When you get a 200 response, the mobile app is registered with Home Assistant. The response is a JSON document and will contain the URLs on how to interact with the Home Assistant instance. You should permanently store this information.

{
  "cloudhook_url": "https://hooks.nabu.casa/randomlongstring123",
  "remote_ui_url": "https://randomlongstring123.ui.nabu.casa",
  "secret": "qwerty",
  "webhook_id": "abcdefgh"
}

Key	Type	Description
cloudhook_url	string	The cloudhook URL provided by Home Assistant Cloud. Only will be provided if user is actively subscribed to Nabu Casa.
remote_ui_url	string	The remote UI URL provided by Home Assistant Cloud. Only will be provided if user is actively subscribed to Nabu Casa.
secret	string	The secret to use for encrypted communication. Will only be included if encryption is supported by both the app and the Home Assistant instance. More info.
webhook_id	string	The webhook ID that can be used to send data back.