Example of using a service account in both production and development with a .pem key converted from devconsole

service-account-dev-prod.py

import webapp2

from apiclient.discovery import build
from apiclient.errors import HttpError
import httplib2
from oauth2client.client import SignedJwtAssertionCredentials
# Enter your Google Developer Project number
PROJECT_NUMBER = "XXXXXXXXXX"


class main(webapp2.RequestHandler):

  def get(self):
    # Load the key in PEM format that you downloaded from the Google API
    # Console when you created your Service account. Convert with:
    # openssl pkcs12 -passin pass:notasecret -in privatekey.p12 -nocerts \
    # -passout pass:notasecret -out key.pem
    # openssl pkcs8 -nocrypt -in key.pem -passin pass:notasecret -topk8 \
    # -out privatekey.pem; rm key.pem

    f = file("privatekey.pem", "rb")
    key = f.read()
    f.close()

    # Create an httplib2.Http object to handle HTTP requests and authorize it
    # with the Credentials. Note that the first parameter, service_account_name,
    # is the Email address created for the Service account. It must be the email
    # address associated with the key that was created.
    credentials = SignedJwtAssertionCredentials(
        "XXXXXXXXXX-HASH"
        "@developer.gserviceaccount.com",
        key,
        scope="https://www.googleapis.com/auth/bigquery")
    http = httplib2.Http()
    http = credentials.authorize(http)