# 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 ro 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, 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:

- `.get(key)`

- `.set(key, value, expires=None)`

## 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 `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 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

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

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

Before using signal, make sure you have installed 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 register 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.