Flask OAuth Client

This documentation covers OAuth 1.0, OAuth 2.0 and OpenID Connect Client support for Flask. Looking for OAuth providers?

• Flask OAuth 1.0 Server

• Flask OAuth 2.0 Server

Flask OAuth client can handle OAuth 1 and OAuth 2 services. It shares a similar API with Flask-OAuthlib, you can transfer your code from Flask-OAuthlib to Authlib with ease.

Create a registry with OAuth object:

from authlib.integrations.flask_client import OAuth

oauth = OAuth(app)

You can also initialize it later with init_app() method:

oauth = OAuth()
oauth.init_app(app)

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

Important

Please read Web OAuth Clients at first. Authlib has a shared API design among framework integrations, learn them from Web OAuth Clients.

Configuration

Authlib Flask OAuth registry can load the configuration from Flask app.config automatically. Every key-value pair in .register can be omitted. They can be configured in your Flask App configuration. Config keys are formatted as {name}_{key} in uppercase, e.g.

TWITTER_CLIENT_ID	Twitter Consumer Key
TWITTER_CLIENT_SECRET	Twitter Consumer Secret
TWITTER_REQUEST_TOKEN_URL	URL to fetch OAuth request token

If you register your remote app as oauth.register('example', ...), the config keys would look like:

EXAMPLE_CLIENT_ID	OAuth Consumer Key
EXAMPLE_CLIENT_SECRET	OAuth Consumer Secret
EXAMPLE_ACCESS_TOKEN_URL	URL to fetch OAuth access token

Here is a full list of the configuration keys:

• {name}_CLIENT_ID: Client key of OAuth 1, or Client ID of OAuth 2

• {name}_CLIENT_SECRET: Client secret of OAuth 2, or Client Secret of OAuth 2

• {name}_REQUEST_TOKEN_URL: Request Token endpoint for OAuth 1

• {name}_REQUEST_TOKEN_PARAMS: Extra parameters for Request Token endpoint

• {name}_ACCESS_TOKEN_URL: Access Token endpoint for OAuth 1 and OAuth 2

• {name}_ACCESS_TOKEN_PARAMS: Extra parameters for Access Token endpoint

• {name}_AUTHORIZE_URL: Endpoint for user authorization of OAuth 1 or OAuth 2

• {name}_AUTHORIZE_PARAMS: Extra parameters for Authorization Endpoint.

• {name}_API_BASE_URL: A base URL endpoint to make requests simple

• {name}_CLIENT_KWARGS: Extra keyword arguments for OAuth1Session or OAuth2Session

We suggest that you keep ONLY {name}_CLIENT_ID and {name}_CLIENT_SECRET in your Flask application configuration.

Using Cache for Temporary Credential

By default, the Flask OAuth registry will use Flask session to store OAuth 1.0 temporary credential (request token). However, in this way, there are chances your temporary credential will be exposed.

Our OAuth registry provides a simple way to store temporary credentials in a cache system. When initializing OAuth, you can pass an cache instance:

oauth = OAuth(app, cache=cache)

# or initialize lazily
oauth = OAuth()
oauth.init_app(app, cache=cache)

A cache instance MUST have methods:

• .delete(key)

• .get(key)

• .set(key, value, expires=None)

An example of a cache instance can be:

from flask import Flask

class OAuthCache:

    def __init__(self, app: Flask) -> None:
        """Initialize the AuthCache."""
        self.app = app

    def delete(self, key: str) -> None:
        """
        Delete a cache entry.

        :param key: Unique identifier for the cache entry.
        """

    def get(self, key: str) -> str | None:
        """
        Retrieve a value from the cache.

        :param key: Unique identifier for the cache entry.
        :return: Retrieved value or None if not found or expired.
        """

    def set(self, key: str, value: str, expires: int | None = None) -> None:
        """
        Set a value in the cache with optional expiration.

        :param key: Unique identifier for the cache entry.
        :param value: Value to be stored.
        :param expires: Expiration time in seconds. Defaults to None (no expiration).
        """

Routes for Authorization

Unlike the examples in Web OAuth Clients, Flask does not pass a request into routes. In this case, the routes for authorization should look like:

from flask import url_for, redirect

@app.route('/login')
def login():
    redirect_uri = url_for('authorize', _external=True)
    return oauth.twitter.authorize_redirect(redirect_uri)

@app.route('/authorize')
def authorize():
    token = oauth.twitter.authorize_access_token()
    resp = oauth.twitter.get('account/verify_credentials.json')
    resp.raise_for_status()
    profile = resp.json()
    # do something with the token and profile
    return redirect('/')

Accessing OAuth Resources

There is no request in accessing OAuth resources either. Just like above, we don’t need to pass the request parameter, everything is handled by Authlib automatically:

from flask import render_template

@app.route('/github')
def show_github_profile():
    resp = oauth.github.get('user')
    resp.raise_for_status()
    profile = resp.json()
    return render_template('github.html', profile=profile)

In this case, our fetch_token could look like:

from your_project import current_user

def fetch_token(name):
    if name in OAUTH1_SERVICES:
        model = OAuth1Token
    else:
        model = OAuth2Token

    token = model.find(
        name=name,
        user=current_user,
    )
    return token.to_token()

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

You don’t have to pass token, you don’t have to pass request. That is the fantasy of Flask.

Auto Update Token via Signal

Added in version v0.13: The signal is added since v0.13

Instead of defining an update_token method and passing it into the OAuth registry, it is also possible to use a signal to listen for token updating.

Before using the signal, make sure you have installed the blinker library:

$ pip install blinker

Connect the token_update signal:

from authlib.integrations.flask_client import token_update

@token_update.connect_via(app)
def on_token_update(sender, 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()

Flask OpenID Connect Client

An OpenID Connect client is no different than a normal OAuth 2.0 client. When registered with openid scope, the built-in Flask OAuth client will handle everything automatically:

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

When we get the returned token:

token = oauth.google.authorize_access_token()

There should be a id_token in the response. Authlib has called .parse_id_token automatically, we can get userinfo in the token:

userinfo = token['userinfo']

Examples

Here are some example projects for you to learn Flask OAuth client integrations:

1. OAuth 1.0: Flask Twitter Login.

2. OAuth 2.0 & OpenID Connect: Flask Google Login.