Google Cloud function Authentication with Firebase

main.py

import firebase_admin
from firebase_admin import auth
from firebase_admin import db
import json

# Initialize the app without credentials, as the function gets it from context
firebase_admin.initialize_app()

def hello_world(request):

    # "1: Check authentication"
    authorization = request.headers.get('Authorization')
    if authorization is None:
        print('Authorization failed. Unexisting token.')
        return 'Authorization failed. Unexisting token.'
    token = authorization.split('Bearer ')[1]
    # create empty variable uid
    uid = None
    try:
        # This will fail in every situation BUT successful authentication
        decode_token = auth.verify_id_token(id_token=token)
        # extract uid from decoded token
        uid = decode_token['uid']
    except Exception as e:
        print('Authorization failed. Invalide token.')
        print(e)
        return 'Authorization failed. Invalide token.'
    # Handle unexisting uid
    if uid is None:
        print('Authorization failed. Unknown user UID')
        return 'Authorization failed. Unknown user UID'
    # Here user if authenticate from Fierbase Authentication service
    print('Authorization suceeded! UID: ' + uid)

    # "2: Check if user have existing credits to run function"
    # The user credit amount is updated form the frontend when user triggers an action
    # Get a database reference to jobr user accounnt cerdiit
    ref = db.reference('jobr-credit/' + uid)
    credit = ref.get()
    # if crerdit amount is less or equal to than 0, return error
    if credit <= 0:
        print('User have no credits')
        return 'User have no credits'
    # "3: Here you can write instruction that will only executed if user is Authenticated from Firebase service"
    print('User have credits')

    # return result as json object
    value = {'uid': uid, 'credit': credit}
    return json.dumps(value)

    
    

requirements.txt

# Function dependencies, for example:
# package>=version
firebase_admin>=5