Can't authenticate Tag Manager API through OAuth in Django when deployed on Google App Engine

[Nicolò Zanellato]

I have a Django app that access data from Google Tag Manager using its API. It works fine locally, but when it is deployed and I try to authenticate, I get this message:

UserWarning: Cannot access tagmanager.dat: No such file or directory

Your browser has been opened to visit:

https://accounts.google.com/o/oauth2/auth?scope=https%3A%2F%2Fwww.googleapis.com%...........
If your browser is on a different machine then exit and re-run this
application with the command-line parameter

--noauth_local_webserver

And the browser doesn't open a new window for authentication which leads to a timeout error.

views.py

import argparse
import sys
import os
import httplib2

from apiclient.discovery import build
from oauth2client import client
from oauth2client import file
from oauth2client import tools

import pandas as pd

def GetService(api_name, api_version, scope, client_secrets_path):
    parser = argparse.ArgumentParser(
      formatter_class=argparse.RawDescriptionHelpFormatter,
      parents=[tools.argparser])
    flags = parser.parse_args([])

    credentials = run_flow(flow, storage, args)

    flow = client.flow_from_clientsecrets(
    client_secrets_path, scope=scope,
    message=tools.message_if_missing(client_secrets_path))

    storage = file.Storage(api_name + '.dat')
    credentials = storage.get()
    if credentials is None or credentials.invalid:
        credentials = tools.run_flow(flow, storage, flags)
        http = credentials.authorize(http=httplib2.Http())

    service = build(api_name, api_version, http=credentials.authorize(http=httplib2.Http()))

    return service

I have also tried to add flags.noauth_local_webserver = True as suggested here, but no luck.

My API configuration is as follows:

Client ID for Web Application

Authorised JavaScript origins URI: https://myapp.appspot.com Authorised redirect URIs: https://myapp.appspot.com/accounts/google/login/callback/

I am not sure about the API configuration and the Google docs are absolutely useless on this matter.

Other questions on Stackoverflow are either too old or not related to this. I have also deployed it to Heroku, but I have the same issue there too

How do I fix this issue?

[Manpreet Sidhu (Google Cloud Support)]

Thanks for reaching out. I suggest that you consider looking into the Tag Manager documentation as that is outside the scope of App Engine.

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