google app engine standard firebase authentication problem

Question

I'm trying to write an API in Google App Engine Standard using Endpoints Framework. I followed the tutorial at https://cloud.google.com/endpoints/docs/frameworks/python/get-started-frameworks-python. "Opened" methods works fine, but I have problems when I want to secure the API with Firebase authentication. Following the tutorial at https://cloud.google.com/endpoints/docs/frameworks/python/authenticating-users, I wrote the following code:

import endpoints
from endpoints import message_types
from endpoints import messages
from endpoints import remote


class EchoRequest(messages.Message):
    message = messages.StringField(1)

class EchoResponse(messages.Message):
    """A proto Message that contains a simple string field."""
    message = messages.StringField(1)


ECHO_RESOURCE = endpoints.ResourceContainer(
    EchoRequest,
    n=messages.IntegerField(2, default=1))

@endpoints.api(
    name='echo',
    version='v1',
    issuers={'firebase': endpoints.Issuer(
   'https://securetoken.google.com/project_name',
    'https://www.googleapis.com/service_accounts/v1/metadata/x509/securetoken@system.gserviceaccount.com')})
class EchoApi(remote.Service):
    @endpoints.method(
        # This method takes a ResourceContainer defined above.                                                                               
        ECHO_RESOURCE,
        # This method returns an Echo message.                                                                                               
        EchoResponse,
        path='test_firebase',
        http_method='POST',
        name='test_firebase')
    def test_firebase(self, request):
        user = endpoints.get_current_user()
        # If there's no user defined, the request was unauthenticated, so we                                                                 
        # raise 401 Unauthorized.                                                                                                            
        if not user:
            raise endpoints.UnauthorizedException
        output_message = ' '.join([request.message] * 3)
        return EchoResponse(message=output_message)

When I try this method using the following curl:

TOKEN="token_string"
curl -i \
     -H "Authorization: Bearer ${TOKEN}" \
     -H "Content-Type: application/json" \
     -X POST -d '{"message":"hello world"}'  https://project_name.appspot.com/_ah/api/echo/v1/test_firebase

I have the following error:

HTTP/2 401 
content-type: application/json
x-cloud-trace-context: ffd02c47eb5885d6a93c31ac8aae26cc;o=1
date: Fri, 20 Dec 2019 17:55:57 GMT
server: Google Frontend
content-length: 150
alt-svc: quic=":443"; ma=2592000; v="46,43",h3-Q050=":443"; ma=2592000,h3-Q049=":443"; ma=2592000,h3-Q048=":443"; ma=2592000,h3-Q046=":443"; ma=2592000,h3-Q043=":443"; ma=2592000

{
 "error": {
  "code": 401, 
  "errors": [
   {
    "domain": "global", 
    "message": "", 
    "reason": "required"
   }
  ], 
  "message": ""
 }
}

Where is the error?

the issue lies in the user = endpoints.get_current_user() which probably is returning nothing because your curl command is not succefuly working( probably due to the access token) which in turn run the line if not user:raise endpoints.UnauthorizedException (401 error). make sure you are passing the right token and use $TOKEN instead of ${TOKEN} — Methkal Khalawi
Yes, the problem is in the line: user = endpoints.get_current_user(), but there isn't any problem with the token, because the same curl command is used against an App Engine Flexible instance version of the API and works correctly. I found this link: groups.google.com/forum/#!topic/google-cloud-endpoints/… and the problem seems that endpoints.get_current_user () is not working with firebase authentication — alessandro mercadante
I found the problem. In the signature of the method, the keyword audiences must be passed: @endpoints.method( ECHO_RESOURCE, EchoResponse, path='test_firebase', audiences={ "firebase": [project_id]}, http_method='POST', name='test_firebase') def test_firebase(self, request): user = endpoints.get_current_user() if not user: raise endpoints.UnauthorizedException — alessandro mercadante
@alessandromercadante Would you mind posting an answer so that the question doesn't appear unanswered? Thanks. — Dan Cornilescu

Clint Clint · Accepted Answer · 2020-04-19T19:27:15

(From alessandromercadante@'s comment, which does NOT work for me. Since it works for some and there is no answer yet, I copied it here to keep the thread going)

In the signature of the method, the keyword audiences must be passed:

@endpoints.method(
  ECHO_RESOURCE,
  EchoResponse,
  path='test_firebase',
  audiences={ "firebase": [project_id]},
  http_method='POST',
  name='test_firebase') 
def test_firebase(self, request):
  user = endpoints.get_current_user()
  if not user:
    raise endpoints.UnauthorizedException

google app engine standard firebase authentication problem

1 Answers