Token has been expired or revoked

Hi,

First of all, I think this issue is not caused by django-gmailapi-backend but a Google OAuth2, even so, I expose my case for if I'm wrong.

I configured the package with GMAIL_API_CLIENT_ID, GMAIL_API_CLIENT_SECRET and GMAIL_API_REFRESH_TOKEN and everything works fine until today.

Six months ago ( exactly six month ago, for this I think it's not a issue of this package ), I created the credentials from GCP, and suddenly today, without any change, I started to get google.auth.exceptions.RefreshError: ('invalid_grant: Token has been expired or revoked.', '{\n "error": "invalid_grant",\n "error_description": "Token has been expired or revoked."\n}')

By now, I fixed this issue by generating again the refresh token by using gmail_oauth2 --generate_oauth2_token ... as the first time I did and replace it for the old one and now seems to work.

I've read that after 6 months, if refresh token is not used, refresh token is expired, so my question is, is the refresh token never used by django-gmailapi-backend? My understanding is yes, because the access token expires after 1 hour and uses de refresh token to renew it, and almost every day my app is sending mails and I have'nt found no problem until now.

If helps, my OAuth consent screen is of type Internal, I don't know if this can be a reason of the trouble.

For more details, I let the full error traceback:

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/gunicorn/workers/sync.py", line 136, in handle
    self.handle_request(listener, req, client, addr)
  File "/usr/local/lib/python3.8/site-packages/gunicorn/workers/sync.py", line 179, in handle_request
    respiter = self.wsgi(environ, resp.start_response)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/wsgi.py", line 133, in __call__
    response = self.get_response(request)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 130, in get_response
    response = self._middleware_chain(request)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 49, in inner
    response = response_for_exception(request, exc)
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/exception.py", line 115, in response_for_exception
    log_response(
  File "/usr/local/lib/python3.8/site-packages/django/utils/log.py", line 224, in log_response
    getattr(logger, level)(
  File "/usr/local/lib/python3.8/logging/__init__.py", line 1475, in error
    self._log(ERROR, msg, args, **kwargs)
  File "/usr/local/lib/python3.8/logging/__init__.py", line 1589, in _log
    self.handle(record)
  File "/usr/local/lib/python3.8/logging/__init__.py", line 1599, in handle
    self.callHandlers(record)
  File "/usr/local/lib/python3.8/logging/__init__.py", line 1661, in callHandlers
    hdlr.handle(record)
  File "/usr/local/lib/python3.8/logging/__init__.py", line 954, in handle
    self.emit(record)
  File "/usr/local/lib/python3.8/site-packages/django/utils/log.py", line 122, in emit
    self.send_mail(subject, message, fail_silently=True, html_message=html_message)
  File "/usr/local/lib/python3.8/site-packages/django/utils/log.py", line 125, in send_mail
    mail.mail_admins(subject, message, *args, connection=self.connection(), **kwargs)
  File "/usr/local/lib/python3.8/site-packages/django/core/mail/__init__.py", line 104, in mail_admins
    mail.send(fail_silently=fail_silently)
  File "/usr/local/lib/python3.8/site-packages/django/core/mail/message.py", line 284, in send
    return self.get_connection(fail_silently).send_messages([self])
  File "/usr/local/lib/python3.8/site-packages/gmailapi_backend/mail.py", line 61, in send_messages
    batch.execute()
  File "/usr/local/lib/python3.8/site-packages/googleapiclient/_helpers.py", line 134, in positional_wrapper
    return wrapped(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/googleapiclient/http.py", line 1557, in execute
    self._refresh_and_apply_credentials(request, http)
  File "/usr/local/lib/python3.8/site-packages/googleapiclient/http.py", line 1249, in _refresh_and_apply_credentials
    _auth.refresh_credentials(creds)
  File "/usr/local/lib/python3.8/site-packages/googleapiclient/_auth.py", line 130, in refresh_credentials
    return credentials.refresh(request)
  File "/usr/local/lib/python3.8/site-packages/google/oauth2/credentials.py", line 208, in refresh
    access_token, refresh_token, expiry, grant_response = _client.refresh_grant(
  File "/usr/local/lib/python3.8/site-packages/google/oauth2/_client.py", line 248, in refresh_grant
    response_data = _token_endpoint_request(request, token_uri, body)
  File "/usr/local/lib/python3.8/site-packages/google/oauth2/_client.py", line 124, in _token_endpoint_request
    _handle_error_response(response_body)
  File "/usr/local/lib/python3.8/site-packages/google/oauth2/_client.py", line 60, in _handle_error_response
    raise exceptions.RefreshError(error_details, response_body)
google.auth.exceptions.RefreshError: ('invalid_grant: Token has been expired or revoked.', '{\n  "error": "invalid_grant",\n  "error_description": "Token has been expired or revoked."\n}')

If somone can bring me some light of this problem I will be very grateful.

Thank you very much in advance,

dolfim / django-gmailapi-backend

Token has been expired or revoked #9