authenticating to google API using Service Account credentials

gistfile1.py

import httplib2

# these are from the google-api-python-client package
from apiclient.discovery import build
from oauth2client.client import SignedJwtAssertionCredentials


def _get_google_service(email, key):
    """Get a Google API client using Service Account credentials"""
    credentials = SignedJwtAssertionCredentials(
        email, key, scope='https://www.googleapis.com/auth/analytics.readonly')
    http = httplib2.Http()
    http = credentials.authorize(http)
    service = build('analytics', 'v3', http=http)
    return service