使用Gmail API和Google App-Engine时的身份验证

Question

This might (once again) be a silly/basic question. But here it goes.

I am trying to build a web-app that queries and displays some information from the user's Gmail. My current idea is as follows:

• Have the backend run on Google AppEngine (coded in Python) where it has endpoints that take in queries like "How many such emails in the past one month" and returns the correct answer.

• The frontend can be a website or an android app that can query the endpoints using REST.

The issue currently is with Authentication. I would like to know the right flow of authentication for my app. As far I see, there are two potential options:

1) Use the front-end to check if the user is logged in. If not, authenticate and send the user credentials to the backend (using the javascript version of GMAIL API perhaps?). 2) Let the backend handle the authentication. Once it gets the query on the endpoints, if the user is not authenticated, it redirects the user to a login page. One of the issues I have with this is that I am using the Python on my AppEngine and all the GMAIL API tutorial for Python requires reading the credentials/clientID from a JSON file on the hard disk. This is not possible on AppEngine since we cannot store any file on local disk.

Can someone point me in the right direction?

Thanks.

Answer 1

You don't need Google cloud storage to store the JSON file you can store it in the App Engine it self, and also without storing inside the JSON file you can directly use it as clientID in the code itself.

client_id and client_secret within the JSON file

from oauth2client.client import flow_from_clientsecrets
...
flow = flow_from_clientsecrets('path_to_directory/client_secrets.json',
                               scope='https://www.googleapis.com/auth/calendar',
                               redirect_uri='http://example.com/auth_return')

Without storing inside the JSON file

from oauth2client.client import OAuth2WebServerFlow
...
flow = OAuth2WebServerFlow(client_id='your_client_id',
                           client_secret='your_client_secret',
                           scope='https://www.googleapis.com/auth/calendar',
                           redirect_uri='http://example.com/auth_return')

Please refer this documentation for further details