julienmeyer / pyramid_jwt

JWT authentication for Pyramid

JWT authentication for Pyramid

This package implements an authentication policy for Pyramid that using JSON Web Tokens. This standard (RFC 7519) is often used to secure backens APIs. The excellent PyJWT library is used for the JWT encoding / decoding logic.

Enabling JWT support in a Pyramid application is very simple:

from pyramid.config import Configurator
from pyramid.authorization import ACLAuthorizationPolicy

def main():
    config = Configurator()
    # Pyramid requires an authorization policy to be active.
    config.set_authorization_policy(ACLAuthorizationPolicy())
    # Enable JWT authentication.
    config.include('pyramid_jwt')
    config.set_jwt_authentication_policy('secret')

This will set a JWT authentication policy using the Authorization HTTP header with a JWT scheme to retrieve tokens. Using another HTTP header is trivial:

config.set_jwt_authentication_policy('secret', http_header='X-My-Header')

To make creating valid tokens easier a new create_jwt_token method is added to the request. You can use this in your view to create tokens. A simple authentication view for a REST backend could look something like this:

@view_config('login', request_method='POST', renderer='json')
def login(request):
    login = request.POST['login']
    password = request.POST['password']
    user_id = authenticate(login, password)  # You will need to implement this.
    if user_id:
        return {
            'result': 'ok',
            'token': request.create_jwt_token(user_id)
        }
    else:
        return {
            'result': 'error'
        }

Since JWT is typically used via HTTP headers and does not use cookies the standard remember() and forget() functions from Pyramid are not useful. Trying to use them while JWT authentication is enabled will result in a warning.

Extra claims

Normally pyramid_jwt only makes a single JWT claim: the subject (or sub claim) is set to the principal. You can also add extra claims to the token by passing keyword parameters to the create_jwt_token method.

token = request.create_jwt_token(user.id,
    name=user.name,
    admin=(user.role == 'admin'))

All claims found in a JWT token can be accessed through the jwt_claims dictionary property on a request. For the above example you can retrieve the name and admin-status for the user directly from the request:

print('User id: %d' % request.authenticated_userid)
print('Users name: %s', request.jwt_claims['name'])
if request.jwt_claims['admin']:
   print('This user is an admin!')

Keep in mind that data jwt_claims only reflects the claims from a JWT token and do not check if the user is valid: the callback configured for the authentication policy is not checked. For this reason you should always use request.authenticated_userid instead of request.jwt_claims['sub'].

You can also use extra claims to manage extra principals for users. For example you could claims to represent add group membership or roles for a user. This requires two steps: first add the extra claims to the JWT token as shown above, and then use the authentication policy's callback hook to turn the extra claim into principals. Here is a quick example:

def add_role_principals(userid, request):
   return ['role:%s' % role for role in request.jwt_claims.get('roles', [])]

config.set_jwt_authentication_policy(callback=add_role_principals)

You can then use the role principals in an ACL:

class MyView:
    __acl__ = [
        (Allow, Everyone, ['read']),
        (Allow, 'role:admin', ['create', 'update']),
    ]

Validation Example

After creating and returning the token through your API with create_jwt_token you can test by issuing an HTTP authorization header type for JWT.

GET /resource HTTP/1.1
Host: server.example.com
Authorization: JWT eyJhbGciOiJIUzI1NiIXVCJ9...TJVA95OrM7E20RMHrHDcEfxjoYZgeFONFh7HgQ

We can test using curl.

curl --header 'Authorization: JWT TOKEN' server.example.com/ROUTE_PATH

config.add_route('example', '/ROUTE_PATH')
@view_config(route_name=example)
def some_action(request):
    if request.authenticated_userid:
        # Do something

Settings

There are a number of flags that specify how tokens are created and verified. You can either set this in your .ini-file, or pass/override them directly to the config.set_jwt_authentication_policy() function.

Parameter	ini-file entry	Default	Description
private_key	jwt.private_key		Key used to hash or sign tokens.
public_key	jwt.public_key		Key used to verify token signatures. Only used with assymetric algorithms.
algorithm	jwt.algorithm	HS512	Hash or encryption algorithm
expiration	jwt.expiration		Number of seconds (or a datetime.timedelta instance) before a token expires.
leeway	jwt.leeway	0	Number of seconds a token is allowed to be expired before it is rejected.
http_header	jwt.http_header	Authorization	HTTP header used for tokens
auth_type	jwt.auth_type	JWT	Authentication type used in Authorization header. Unused for other HTTP headers.
json_encoder		None	A subclass of JSONEncoder to be used to encode principal and claims infos.