auth.py

#!/usr/bin/python

from oauth2client.client import flow_from_clientsecrets
from oauth2client.file import Storage
from oauth2client.tools import run

CLIENT_SECRETS = 'client_secrets.json'
MISSING_CLIENT_SECRETS_MESSAGE = '%s is missing' % CLIENT_SECRETS

FLOW = flow_from_clientsecrets(CLIENT_SECRETS,
  scope='https://www.googleapis.com/auth/analytics.readonly',
  message=MISSING_CLIENT_SECRETS_MESSAGE)

TOKEN_FILE_NAME = 'analytics.dat'

def prepare_credentials():
  storage = Storage(TOKEN_FILE_NAME)
  credentials = storage.get()
  if credentials is None or credentials.invalid:
    credentials = run(FLOW, storage)
  return credentials

prepare_credentials()