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Device code flow

The device code flow is also known as device flow or device authorization grant flow. This type of authentication flow is useful for devices with limited input capabilities and/or devices without browsers. The Request for Comments (RFC) 8628) abstract for this flow states:

The OAuth 2.0 device authorization grant is designed for Internet-connected devices that either lack a browser to perform a user-agent-based authorization or are input constrained to the extent that requiring the user to input text in order to authenticate during the authorization flow is impractical. It enables OAuth clients on such devices (like smart TVs, media consoles, digital picture frames, and printers) to obtain user authorization to access protected resources by using a user agent on a separate device.

Requirements​

This device flow is only possible if the active brand has a device code flow configured. This flow is run after the user logs in, and before the user authenticates.

authentik does not include a default flow for this use case, so it is necessary to create a new one with a Designation of Stage Configuration.

Device flow initiation​

The flow is initiated by sending a POST request to the device authorization endpoint, /application/o/device/, with the following contents:

POST /application/o/device/ HTTP/1.1
Host: authentik.company
Content-Type: application/x-www-form-urlencoded

client_id=application_client_id&
scope=openid email my-other-scope

The response contains the following fields:

  • device_code: Device code, which is the code kept on the device
  • verification_uri: The URL to be shown to the enduser to input the code
  • verification_uri_complete: The same URL as above except the code will be prefilled
  • user_code: The raw code for the enduser to input
  • expires_in: The total seconds after which this token will expire
  • interval: The interval in seconds for how often the device should check the token status

With this response, the device can start checking the status of the token by sending requests to the token endpoint like this:

POST /application/o/token/ HTTP/1.1
Host: authentik.company
Content-Type: application/x-www-form-urlencoded

grant_type=urn:ietf:params:oauth:grant-type:device_code&
client_id=application_client_id&
device_code=device_code_from_above

If the user has not opened the link above yet, or has not finished the authentication and authorization yet, the response will contain an error element set to authorization_pending. The device should re-send the request in the interval set above.

If the user has finished the authentication and authorization, the response will be similar to any other generic OAuth2 Token request, containing access_token and id_token.

Create and apply a device code flow​

  1. Log in to authentik as an admin, and open the authentik Admin interface.
  2. Navigate to Flows and Stages > Flows and click Create.
  3. Set the following required configurations:
    • Name: provide a name (e.g. default-device-code-flow)
    • Title: provide a title (e.g. Device code flow)
    • Slug: provide a slug (e.g default-device-code-flow)
    • Designation: Stage Configuration
    • Authentication: Require authentication
  4. Click Create.
  5. Navigate to System > Brands and click the Edit icon on the default brand.
  6. Set Default code flow to the newly created device code flow and click Update.