oauth2_workflow.rst

OAuth 2 Workflow

• Introduction
  • Available Workflows
• Web Application Flow
• Mobile Application Flow
• Legacy Application Flow
• Backend Application Flow
• Refreshing tokens
  • (ALL) Define the token, token saver and needed credentials
  • (First) Define Try-Catch TokenExpiredError on each request
  • (Second) Define automatic token refresh automatic but update manually
  • (Third, Recommended) Define automatic token refresh and update

Introduction

The following sections provide some example code that demonstrates some of the possible OAuth2 flows you can use with requests-oauthlib. We provide four examples: one for each of the grant types defined by the OAuth2 RFC. These grant types (or workflows) are the Authorization Code Grant (or Web Application Flow), the Implicit Grant (or Mobile Application Flow), the Resource Owner Password Credentials Grant (or, more succinctly, the Legacy Application Flow), and the Client Credentials Grant (or Backend Application Flow).

Available Workflows

There are four core work flows:

1. :ref:`Authorization Code Grant <web-application-flow>` (Web Application Flow).
2. :ref:`Implicit Grant <mobile-application-flow>` (Mobile Application flow).
3. :ref:`Resource Owner Password Credentials Grant <legacy-application-flow>` (Legacy Application flow).
4. :ref:`Client Credentials Grant <backend-application-flow>` (Backend Application flow).

Web Application Flow

The steps below outline how to use the default Authorization Grant Type flow to obtain an access token and fetch a protected resource. In this example the provider is Google and the protected resource is the user's profile.

0. Obtain credentials from your OAuth provider manually. At minimum you will need a client_id but likely also a client_secret. During this process you might also be required to register a default redirect URI to be used by your application. Save these things in your Python script:

>>> client_id = r'your_client_id'
>>> client_secret = r'your_client_secret'
>>> redirect_uri = 'https://your.callback/uri'

1. User authorization through redirection. First we will create an authorization url from the base URL given by the provider and the credentials previously obtained. In addition most providers will request that you ask for access to a certain scope. In this example we will ask Google for access to the email address of the user and the users profile.

# Note that these are Google specific scopes
>>> scope = ['https://www.googleapis.com/auth/userinfo.email',
             'https://www.googleapis.com/auth/userinfo.profile']
>>> oauth = OAuth2Session(client_id, redirect_uri=redirect_uri,
                          scope=scope)
>>> authorization_url, state = oauth.authorization_url(
        'https://accounts.google.com/o/oauth2/auth',
        # access_type and prompt are Google specific extra
        # parameters.
        access_type="offline", prompt="select_account")

>>> print 'Please go to %s and authorize access.' % authorization_url
>>> authorization_response = raw_input('Enter the full callback URL')

2. Fetch an access token from the provider using the authorization code obtained during user authorization.

>>> token = oauth.fetch_token(
        'https://accounts.google.com/o/oauth2/token',
        authorization_response=authorization_response,
        # Google specific extra parameter used for client
        # authentication
        client_secret=client_secret)

3. Access protected resources using the access token you just obtained. For example, get the users profile info.

>>> r = oauth.get('https://www.googleapis.com/oauth2/v1/userinfo')
>>> # Enjoy =)

Mobile Application Flow

The steps below outline how to use the Implicit Code Grant Type flow to obtain an access token.

0. You will need the following settings.

>>> client_id = 'your_client_id'
>>> scopes = ['scope_1', 'scope_2']
>>> auth_url = 'https://your.oauth2/auth'

1. Get the authorization_url

>>> from oauthlib.oauth2 import MobileApplicationClient
>>> from requests_oauthlib import OAuth2Session
>>> oauth = OAuth2Session(client=MobileApplicationClient(client_id=client_id), scope=scopes)
>>> authorization_url, state = oauth.authorization_url(auth_url)

2. Fetch an access token from the provider.

>>> response = oauth.get(authorization_url)
>>> oauth.token_from_fragment(response.url)

Legacy Application Flow

The steps below outline how to use the Resource Owner Password Credentials Grant Type flow to obtain an access token.

0. You will need the following settings. client_secret is optional depending on the provider.

>>> client_id = 'your_client_id'
>>> client_secret = 'your_client_secret'
>>> username = 'your_username'
>>> password = 'your_password'

1. Fetch an access token from the provider.

>>> from oauthlib.oauth2 import LegacyApplicationClient
>>> from requests_oauthlib import OAuth2Session
>>> oauth = OAuth2Session(client=LegacyApplicationClient(client_id=client_id))
>>> token = oauth.fetch_token(token_url='https://somesite.com/oauth2/token',
        username=username, password=password, client_id=client_id,
        client_secret=client_secret)

Backend Application Flow

The steps below outline how to use the Resource Owner Client Credentials Grant Type flow to obtain an access token.

0. Obtain credentials from your OAuth provider. At minimum you will need a client_id and client_secret.

   >>> client_id = 'your_client_id'
   >>> client_secret = 'your_client_secret'

1. Fetch an access token from the provider.

   >>> from oauthlib.oauth2 import BackendApplicationClient
   >>> client = BackendApplicationClient(client_id=client_id)
   >>> oauth = OAuth2Session(client=client)
   >>> token = oauth.fetch_token(token_url='https://provider.com/oauth2/token', client_id=client_id,
           client_secret=client_secret)

   If your provider requires that you pass auth credentials in a Basic Auth header, you can do this instead:

   >>> from oauthlib.oauth2 import BackendApplicationClient
   >>> from requests.auth import HTTPBasicAuth
   >>> auth = HTTPBasicAuth(client_id, client_secret)
   >>> client = BackendApplicationClient(client_id=client_id)
   >>> oauth = OAuth2Session(client=client)
   >>> token = oauth.fetch_token(token_url='https://provider.com/oauth2/token', auth=auth)

Refreshing tokens

Certain providers will give you a refresh_token along with the access_token. These can be used to directly fetch new access tokens without going through the normal OAuth workflow. requests-oauthlib provides three methods of obtaining refresh tokens. All of these are dependant on you specifying an accurate expires_in in the token.

expires_in is a credential given with the access and refresh token indiciating in how many seconds from now the access token expires. Commonly, access tokens expire after an hour an the expires_in would be 3600. Without this it is impossible for requests-oauthlib to know when a token is expired as the status code of a request failing due to token expiration is not defined.

If you are not interested in token refreshing, always pass in a positive value for expires_in or omit it entirely.

(ALL) Define the token, token saver and needed credentials

>>> token = {
...     'access_token': 'eswfld123kjhn1v5423',
...     'refresh_token': 'asdfkljh23490sdf',
...     'token_type': 'Bearer',
...     'expires_in': '-30',     # initially 3600, need to be updated by you
...  }
>>> client_id = r'foo'
>>> refresh_url = 'https://provider.com/token'
>>> protected_url = 'https://provider.com/secret'

>>> # most providers will ask you for extra credentials to be passed along
>>> # when refreshing tokens, usually for authentication purposes.
>>> extra = {
...     'client_id': client_id,
...     'client_secret': r'potato',
... }

>>> # After updating the token you will most likely want to save it.
>>> def token_saver(token):
...     # save token in database / session

(First) Define Try-Catch TokenExpiredError on each request

This is the most basic version in which an error is raised when refresh is necessary but refreshing is done manually.

>>> from requests_oauthlib import OAuth2Session
>>> from oauthlib.oauth2 import TokenExpiredError
>>> try:
...     client = OAuth2Session(client_id, token=token)
...     r = client.get(protected_url)
>>> except TokenExpiredError as e:
...     token = client.refresh_token(refresh_url, **extra)
...     token_saver(token)
>>> client = OAuth2Session(client_id, token=token)
>>> r = client.get(protected_url)

(Second) Define automatic token refresh automatic but update manually

This is the, arguably awkward, middle between the basic and convenient refresh methods in which a token is automatically refreshed, but saving the new token is done manually.

>>> from requests_oauthlib import OAuth2Session, TokenUpdated
>>> try:
...     client = OAuth2Session(client_id, token=token,
...             auto_refresh_kwargs=extra, auto_refresh_url=refresh_url)
...     r = client.get(protected_url)
>>> except TokenUpdated as e:
...     token_saver(e.token)

(Third, Recommended) Define automatic token refresh and update

The third and recommended method will automatically fetch refresh tokens and save them. It requires no exception catching and results in clean code. Remember however that you still need to update expires_in to trigger the refresh.

>>> from requests_oauthlib import OAuth2Session
>>> client = OAuth2Session(client_id, token=token, auto_refresh_url=refresh_url,
...     auto_refresh_kwargs=extra, token_updater=token_saver)
>>> r = client.get(protected_url)