Custom Grant type

Writing a custom grant type can be useful to implement a specification which is in an early draft, or implement a grant provided by a specific OAuth2.0 Authorization Server documentation but not provided by oauthlib. For information, any grant types with a clear specification can be integrated in oauthlib, just make a PR for that ! See how to contribute here.

Please find how to create a new grant and use it in an endpoint:

1. Define your Grant Type

The heart of your code is done by subclassing GrantTypeBase. If you want to use it in the Authorize endpoint, you will have to implement create_authorization_response(), if you want to use the Token endpoint, implement create_token_response(). You can also implement both.

2. Implement the grant

Inside the method’s implementation, you will have to:

  • add validations of the request (syntax, parameters, …)
  • call and orchestrate one or multiple Request Validators calls
  • generate and return HTTP response

You can define new Request Validator methods if needed, or reuse the existing ones.

3. Associate it with Endpoints

Then, once implemented, you have to instanciate the grant object and bind it to your endpoint. Either AuthorizationEndpoint, TokenEndpoint or both.

4. Example

This example shows how to add a simple extension to the Token endpoint:

  • creation of a new class MyCustomGrant, and implement create_token_response.
  • do basics and custom request validations, then call a custom method of Request Validator to extend the interface for the implementor.
  • instanciate the new grant, and bind it with an existing Server.
grant_name = 'urn:ietf:params:oauth:grant-type:my-custom-grant'

class MyCustomGrant(GrantTypeBase):
    def create_token_response(self, request, token_handler):
        if not request.grant_type == grant_name:
            raise errors.UnsupportedGrantTypeError(request=request)

        # implement your custom validation checks
        # ..
        self.request_validator.your_custom_check(request)

        token = token_handler.create_token(request)
        return self._get_default_headers(), json.dumps(token), 200

def setup_oauthlib():
    my_custom_grant = MyCustomGrant()
    server = Server(request_validator)
    server.grant_types[grant_name] = my_custom_grant

You can find concrete examples directly in the code source of existing grants and existing servers. See Grant Types in oauthlib.oauth2.rfc749.grant_types, and Servers in oauthlib.oauth2.rfc749.endpoints.pre_configured