Web Clients

This documentation covers OAuth 2.0 integrations for Python Web Frameworks like:

  • Django: The web framework for perfectionists with deadlines

  • Flask: The Python micro framework for building web applications

  • Starlette: The little ASGI framework that shines

Authlib shares a common API design among these web frameworks. Instead of introducing them one by one, this documentation contains the common usage for them all.

We start with creating a registry with the OAuth class:

# for Flask framework
from authlib.integrations.flask_client import OAuth

# for Django framework
from authlib.integrations.django_client import OAuth

# for Starlette framework
from authlib.integrations.starlette_client import OAuth

oauth = OAuth()

There are little differences among each framework, you can read their documentation later:

  1. flask_client.OAuth for Flask Integration

  2. django_client.OAuth for Django Integration

  3. starlette_client.OAuth for Starlette Integration

The common use case for OAuth is authentication, e.g. let your users log in with GitHub, Google etc.

Using OAuth 2.0 to Log In

For instance, GitHub is an OAuth 2.0 service, you want your users to log in your website with GitHub.

The first step is register a remote application on the OAuth registry via oauth.register method:

oauth.register(
    name='github',
    client_id='{{ your-github-client-id }}',
    client_secret='{{ your-github-client-secret }}',
    access_token_url='https://github.com/login/oauth/access_token',
    access_token_params=None,
    authorize_url='https://github.com/login/oauth/authorize',
    authorize_params=None,
    api_base_url='https://api.github.com/',
    client_kwargs={'scope': 'user:email'},
)

The first parameter in register method is the name of the remote application. You can access the remote application with:

github = oauth.create_client('github')
# or simply with
github = oauth.github

The configuration of those parameters can be loaded from the framework configuration. Each framework has its own config system, read the framework specified documentation later.

The client_kwargs is a dict configuration to pass extra parameters to OAuth 2 Session, you can pass extra parameters like:

client_kwargs = {
    'scope': 'profile',
    'token_endpoint_auth_method': 'client_secret_basic',
    'token_placement': 'header',
}

There are several token_endpoint_auth_method, get a deep inside the Client Authentication Methods.

Routes for Authorization

After configuring the OAuth registry and the remote application, the rest steps are much simpler. The only required parts are routes:

  1. redirect to 3rd party provider (GitHub) for authentication

  2. redirect back to your website to fetch access token and profile

Here is the example for GitHub login:

def login(request):
    github = oauth.create_client('github')
    redirect_uri = 'https://example.com/authorize'
    return github.authorize_redirect(request, redirect_uri)

def authorize(request):
    token = oauth.github.authorize_access_token(request)
    resp = oauth.github.get('user', token=token)
    resp.raise_for_status()
    profile = resp.json()
    # do something with the token and profile
    return '...'

After user confirmed on GitHub authorization page, it will redirect back to your website authorize. In this route, you can get your user’s GitHub profile information, you can store the user information in your database, mark your user as logged in and etc.

Client Authentication Methods

When fetching access token, the authorization server will require a client authentication, Authlib provides three default methods defined by RFC7591:

  • client_secret_basic

  • client_secret_post

  • none

But if the remote provider does not support these three methods, we need to register our own authentication methods, like Client Authentication:

from authlib.oauth2.rfc7523 import ClientSecretJWT

oauth.register(
    'name',
    ...
    client_auth_methods=[
        ClientSecretJWT(token_endpoint),  # client_secret_jwt
    ]
)

Added in version v0.15: Starting from v0.15, developers can add custom authentication methods directly to token endpoint:

oauth.register(
    'name',
    ...
    token_endpoint_auth_method=ClientSecretJWT(token_endpoint),
)

Accessing OAuth Resources

Note

If your application ONLY needs login via 3rd party services like Google, Facebook and GitHub to login, you DON’T need to create the token database.

There are also chances that you need to access your user’s 3rd party OAuth provider resources. For instance, you want to display the logged in user’s GitHub repositories. You will use access token to fetch the resources:

def get_github_repositories(request):
    token = OAuth2Token.find(
        name='github',
        user=request.user
    )
    # API URL: https://api.github.com/user/repos
    resp = oauth.github.get('user/repos', token=token.to_token())
    resp.raise_for_status()
    return resp.json()

In this case, we need a place to store the access token in order to use it later. Usually we will save the token into database. In the previous Routes for Authorization authorize part, we can save the token into database.

Design Database

Here are some hints on how to design the OAuth 2.0 token database:

class OAuth2Token(Model):
    name = String(length=40)
    token_type = String(length=40)
    access_token = String(length=200)
    refresh_token = String(length=200)
    expires_at = PositiveIntegerField()
    user = ForeignKey(User)

    def to_token(self):
        return dict(
            access_token=self.access_token,
            token_type=self.token_type,
            refresh_token=self.refresh_token,
            expires_at=self.expires_at,
        )

And then we can save user’s access token into database when user was redirected back to our authorize page.

Fetch User OAuth Token

You can always pass a token parameter to the remote application request methods, like:

token = OAuth2Token.find(name='github', user=request.user)
oauth.github.get(url, token=token)
oauth.github.post(url, token=token)
oauth.github.put(url, token=token)
oauth.github.delete(url, token=token)

However, it is not a good practice to query the token database in every request function. Authlib provides a way to fetch current user’s token automatically for you, just register with fetch_token function:

def fetch_github_token(request):
    token = OAuth2Token.find(
        name='github',
        user=request.user
    )
    return token.to_token()

# we can registry this ``fetch_token`` with oauth.register
oauth.register(
    'github',
    # ...
    fetch_token=fetch_github_token,
)

There is also a shared way to fetch token:

def fetch_token(name, request):
    token = OAuth2Token.find(
        name=name,
        user=request.user
    )
    return token.to_token()

# initialize OAuth registry with this fetch_token function
oauth = OAuth(fetch_token=fetch_token)

Now, developers don’t have to pass a token in the HTTP requests, instead, they can pass the request:

def get_github_repos(request):
    resp = oauth.github.get('user/repos', request=request)
    resp.raise_for_status()
    return resp.json()

Note

Flask is different, you don’t need to pass the request either.

OAuth 2.0 Enhancement

OAuth 1.0 is a protocol, while OAuth 2.0 is a framework. There are so many features in OAuth 2.0 than OAuth 1.0. This section is designed for OAuth 2.0 specially.

Auto Update Token

In OAuth 1.0, access token never expires. But in OAuth 2.0, token MAY expire. If there is a refresh_token value, Authlib will auto update the access token if it is expired.

We do this by passing a update_token function to OAuth registry:

def update_token(name, token, refresh_token=None, access_token=None):
    if refresh_token:
        item = OAuth2Token.find(name=name, refresh_token=refresh_token)
    elif access_token:
        item = OAuth2Token.find(name=name, access_token=access_token)
    else:
        return

    # update old token
    item.access_token = token['access_token']
    item.refresh_token = token.get('refresh_token')
    item.expires_at = token['expires_at']
    item.save()

oauth = OAuth(update_token=update_token)

In this way, OAuth 2.0 integration will update expired token automatically. There is also a signal way to update token. Checkout the frameworks documentation.

OAuth 2.0 Code Challenge

Adding code_challenge provided by RFC7636: Proof Key for Code Exchange by OAuth Public Clients is simple. You register your remote app with a code_challenge_method in client_kwargs:

oauth.register(
    'example',
    client_id='Example Client ID',
    client_secret='Example Client Secret',
    access_token_url='https://example.com/oauth/access_token',
    authorize_url='https://example.com/oauth/authorize',
    api_base_url='https://api.example.com/',
    client_kwargs={'code_challenge_method': 'S256'},
)

Note, the only supported code_challenge_method is S256.

Compliance Fix for OAuth 2.0

For non standard OAuth 2.0 service, you can pass a compliance_fix when .register. For example, Slack has a compliance problem, we can construct a method to fix the requests session:

def slack_compliance_fix(session):
    def _fix(resp):
        resp.raise_for_status()
        token = resp.json()
        # slack returns no token_type
        token['token_type'] = 'Bearer'
        resp._content = to_unicode(json.dumps(token)).encode('utf-8')
        return resp
    session.register_compliance_hook('access_token_response', _fix)

Then pass this slack_compliance_fix into .register parameters:

oauth.register(
    'slack',
    client_id='...',
    client_secret='...',
    ...,
    compliance_fix=slack_compliance_fix,
    ...
)

Find all the available compliance hooks at Compliance Fix for non Standard.

OpenID Connect & UserInfo

When logging in with OpenID Connect, “access_token” is not what developers want. Instead, what developers want is user info, Authlib wrap it with UserInfo.

There are two ways to fetch userinfo from 3rd party providers. If the provider supports OpenID Connect, we can get the user info from the returned id_token.

userinfo_endpoint

Passing a userinfo_endpoint when .register remote client:

oauth.register(
    'google',
    client_id='...',
    client_secret='...',
    userinfo_endpoint='https://openidconnect.googleapis.com/v1/userinfo',
)

And later, when the client has obtained the access token, we can call:

def authorize(request):
    token = oauth.google.authorize_access_token(request)
    user = oauth.google.userinfo(token=token)
    return '...'

Parsing id_token

For OpenID Connect provider, when .authorize_access_token, the provider will include a id_token in the response. This id_token contains the UserInfo we need so that we don’t have to fetch userinfo endpoint again.

The id_token is a JWT, with Authlib JSON Web Token (JWT), we can decode it easily. Frameworks integrations will handle it automatically if configurations are correct.

A simple solution is to provide the OpenID Connect Discovery Endpoint:

oauth.register(
    'google',
    client_id='...',
    client_secret='...',
    server_metadata_url='https://accounts.google.com/.well-known/openid-configuration',
    client_kwargs={'scope': 'openid email profile'},
)

The discovery endpoint provides all the information we need so that we don’t have to add authorize_url and access_token_url.

Check out our client example: https://github.com/authlib/demo-oauth-client

But if there is no discovery endpoint, developers MUST add all the missing information themselves:

* authorize_url
* access_token_url
* jwks_uri

This jwks_uri is the URL to get provider’s public JWKs. Developers MAY also provide the value of jwks instead of jwks_uri:

oauth.register(
    'google',
    client_id='...',
    client_secret='...',
    access_token_url='https://example.com/oauth/access_token',
    authorize_url='https://example.com/oauth/authorize',
    jwks={"keys": [...]}
)

RP-Initiated Logout

OpenID Connect RP-Initiated Logout allows users to log out from the OpenID Provider when they log out from your application. This is useful to ensure that the user’s session at the provider is also terminated.

To use RP-Initiated Logout, the provider must support the end_session_endpoint in its OpenID Connect discovery document. Authlib provides a logout_redirect method to redirect users to this endpoint:

def logout(request):
    client = oauth.create_client('google')
    # Retrieve the ID token you stored during login
    id_token = get_stored_id_token(request.user)
    return client.logout_redirect(
        request,
        post_logout_redirect_uri='https://example.com/logged-out',
        id_token_hint=id_token,
    )

The logout_redirect method accepts:

  • post_logout_redirect_uri: Where to redirect after logout (must be registered with the provider)

  • id_token_hint: The ID token previously issued (recommended)

  • state: Opaque value for CSRF protection (auto-generated if not provided)

  • client_id: OAuth 2.0 Client Identifier (optional)

  • logout_hint: Hint about the user logging out (optional)

  • ui_locales: Preferred languages for the logout UI (optional)

Important

You must store the id_token during login to use it later for logout. The id_token is available in token['id_token'] after calling authorize_access_token().

Each framework has slightly different syntax. See the framework-specific documentation for detailed examples: