Flask OAuth Client¶

Looking for OAuth providers?

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. Here is how to Migrate OAuth Client from Flask-OAuthlib to Authlib.

Create a registry with OAuth object:

from authlib.flask.client import OAuth

oauth = OAuth(app)

You can initialize it later with init_app() method:

oauth = OAuth()
oauth.init_app(app)

Configuration¶

To register a remote application on OAuth registry, using the register() method:

oauth.register(
    name='twitter',
    client_id='Twitter Consumer Key',
    client_secret='Twitter Consumer Secret',
    request_token_url='https://api.twitter.com/oauth/request_token',
    request_token_params=None,
    access_token_url='https://api.twitter.com/oauth/access_token',
    access_token_params=None,
    refresh_token_url=None,
    authorize_url='https://api.twitter.com/oauth/authenticate',
    api_base_url='https://api.twitter.com/1.1/',
    client_kwargs=None,
)

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

oauth.twitter.get('account/verify_credentials.json')

The second parameter in register method is configuration. Every key value pair can be omit. They can be configured in your Flask App configuration. Config key is formatted with {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 key would look like:

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

The remote app that OAuth.register() configured, is a subclass of OAuthClient. You can read more on OAuthClient. There are hooks for OAuthClient, and flask integration has registered them all for you.

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}_REFRESH_TOKEN_URL: Refresh Token endpoint for OAuth 2 (if any)
{name}_REFRESH_TOKEN_PARAMS: Extra parameters for Refresh 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

CLIENT_KWARGS¶

The {name}_CLIENT_KWARGS is a dict configuration to pass extra parameters to OAuth1Session or OAuth2Session.

For OAuth 1.0, you can pass extra parameters like:

EXAMPLE_CLIENT_KWARGS = {
    'signature_method': 'HMAC-SHA1',
    'signature_type': 'HEADER',
    'rsa_key': 'Your-RSA-Key'
}

For OAuth 2.0, you can pass extra parameters like:

EXAMPLE_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.

Database¶

Note

If OAuth login is what you need ONLY, you don’t need to configure a database with fetch_token method.

We need to fetch_token from database for later requests. Here is an example on database schema design:

class OAuth1Token(db.Model)
    user_id = Column(Integer, nullable=False)
    name = Column(String(20), nullable=False)

    oauth_token = Column(String(48), nullable=False)
    oauth_token_secret = Column(String(48))

    def to_token(self):
        return dict(
            oauth_token=self.access_token,
            oauth_token_secret=self.alt_token,
        )

class OAuth2Token(db.Model):
    user_id = Column(Integer, nullable=False)
    name = Column(String(20), nullable=False)

    token_type = Column(String(20))
    access_token = Column(String(48), nullable=False)
    refresh_token = Column(String(48))
    expires_at = Column(Integer, default=0)

    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,
        )

To send requests on behalf of the user, you need to save user’s access token into database after authorize_access_token. Then use the access token with fetch_token from database.

OAuth 1 Request Token¶

OAuth 1 requires a temporary request token for exchanging access token. There should be a place to store these temporary information. If a cache system is available, the ONLY thing you need to do is pass the cache instance into OAuth registry. A cache interface MUST have methods:

.get(key)
.set(key, value, expires=None)

Pass the cache instance into OAuth registry:

from authlib.flask.client import OAuth

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

If cache system is not available, you can define methods for retrieving and saving request token:

def save_request_token(token):
    save_request_token_to_someplace(current_user, token)

def fetch_request_token():
    return get_request_token_from_someplace(current_user)

# register the two methods
oauth.register('twitter',
    client_id='Twitter Consumer Key',
    client_secret='Twitter Consumer Secret',
    request_token_url='https://api.twitter.com/oauth/request_token',
    request_token_params=None,
    access_token_url='https://api.twitter.com/oauth/access_token',
    access_token_params=None,
    refresh_token_url=None,
    authorize_url='https://api.twitter.com/oauth/authenticate',
    api_base_url='https://api.twitter.com/1.1/',
    client_kwargs=None,
    # NOTICE HERE
    save_request_token=save_request_token,
    fetch_request_token=fetch_request_token,
)

Note

There is no “request token” in OAuth 2.0, you don’t need to implement this section if your are working on OAuth 2.0 integrations.

Flask OAuth Clients Routes¶

Let’s take Twitter as an example, we need to define routes for login and authorization:

from flask import url_for, render_template

@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()
    # this is a pseudo method, you need to implement it yourself
    OAuth1Token.save(current_user, token)
    return redirect(url_for('twitter_profile'))

@app.route('/profile')
def twitter_profile():
    resp = oauth.twitter.get('account/verify_credentials.json')
    profile = resp.json()
    return render_template('profile.html', profile=profile)

There will be an issue with /profile since you our registry don’t know current user’s Twitter access token. We need to design a fetch_token, and grant it to the registry:

def fetch_twitter_token():
    item = OAuth1Token.query.filter_by(
        name='twitter', user_id=current_user.id
    ).first()
    return item.to_token()

# we can registry this ``fetch_token`` with oauth.register
oauth.register(
    'twitter',
    client_id='Twitter Consumer Key',
    client_secret='Twitter Consumer Secret',
    request_token_url='https://api.twitter.com/oauth/request_token',
    request_token_params=None,
    access_token_url='https://api.twitter.com/oauth/access_token',
    access_token_params=None,
    refresh_token_url=None,
    authorize_url='https://api.twitter.com/oauth/authenticate',
    api_base_url='https://api.twitter.com/1.1/',
    client_kwargs=None,
    # NOTICE HERE
    fetch_token=fetch_twitter_token,
)

Since the OAuth registry can contain many services, it would be good enough to share some common methods instead of defining them one by one. Here are some hints:

from flask import url_for, render_template

@app.route('/login/<name>')
def login(name):
    client = oauth.create_client(name)
    redirect_uri = url_for('authorize', name=name, _external=True)
    return client.authorize_redirect(redirect_uri)

@app.route('/authorize/<name>')
def authorize(name):
    client = oauth.create_client(name)
    token = client.authorize_access_token()
    if name in OAUTH1_SERVICES:
        # this is a pseudo method, you need to implement it yourself
        OAuth1Token.save(current_user, token)
    else:
        # this is a pseudo method, you need to implement it yourself
        OAuth2Token.save(current_user, token)
    return redirect(url_for('profile', name=name))

@app.route('/profile/<name>')
def profile(name):
    client = oauth.create_client(name)
    resp = oauth.twitter.get(get_profile_url(name))
    profile = resp.json()
    return render_template('profile.html', profile=profile)

We can share a fetch_token method at OAuth registry level when initialization. Define a common fetch_token:

def fetch_token(name):
    if name in OAUTH1_SERVICES:
        item = OAuth1Token.query.filter_by(
            name=name, user_id=current_user.id
        ).first()
    else:
        item = OAuth2Token.query.filter_by(
            name=name, user_id=current_user.id
        ).first()
    if item:
        return item.to_token()

# pass ``fetch_token``
oauth = OAuth(app, fetch_token=fetch_token)

# or init app later
oauth = OAuth(fetch_token=fetch_token)
oauth.init_app(app)

# or init everything later
oauth = OAuth()
oauth.init_app(app, fetch_token=fetch_token)

With this common fetch_token in OAuth, you don’t need to design the method for each services one by one.

Auto Refresh Token¶

In OAuth 2, there is a concept of refresh_token, Authlib can auto refresh access token when it is expired. If the services you are using don’t issue any refresh_token at all, you don’t need to do anything.

Just like fetch_token, we can define a update_token method for each remote app or sharing it in OAuth registry:

def update_token(name, token):
    item = OAuth2Token.query.filter_by(
        name=name, user_id=current_user.id
    ).first()
    if not item:
        item = OAuth2Token(name=name, user_id=current_user.id)
    item.token_type = token.get('token_type', 'bearer')
    item.access_token = token.get('access_token')
    item.refresh_token = token.get('refresh_token')
    item.expires_at = token.get('expires_at')
    db.session.add(item)
    db.session.commit()
    return item

# pass ``update_token``
oauth = OAuth(app, update_token=update_token)

# or init app later
oauth = OAuth(update_token=update_token)
oauth.init_app(app)

# or init everything later
oauth = OAuth()
oauth.init_app(app, update_token=update_token)

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:

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=None,
    code_challenge_method='S256',
)

Note, the only supported code_challenge_method is S256.

Compliance Fix¶

The RemoteApp is a subclass of OAuthClient, they share the same logic for compliance fix. Construct a method to fix requests session:

def slack_compliance_fix(session):
    def _fix(resp):
        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)

When OAuth.register() a remote app, pass it in the 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.

Loginpass¶

There are many built-in integrations served by loginpass, checkout the flask_example in loginpass project. Here is an example of GitHub:

from flask import Flask
from authlib.flask.client import OAuth
from loginpass import create_flask_blueprint, GitHub

app = Flask(__name__)
oauth = OAuth(app)

def handle_authorize(remote, token, user_info):
    if token:
        save_token(remote.name, token)
    if user_info:
        save_user(user_info)
        return user_page
    raise some_error

github_bp = create_flask_blueprint(GitHub, oauth, handle_authorize)
app.register_blueprint(github_bp, url_prefix='/github')
# Now, there are: ``/github/login`` and ``/github/auth``

The source code of loginpass is very simple, they are just preconfigured services integrations.

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