Google API (gapi)
Easy enough (for me) Google API
Export variable environment
GAPI_SERVICE_ACCOUNT_KEY="/directory/key.p12" GAPI_SERVICE_ACCOUNT_EMAIL="emailaddress@developer.gserviceaccount.com" GAPI_SERVICE_ACCOUNT_USER="user@domain.com"
Or, to use App Engine production credentials set GAPI_USE_APPENGINE_CREDENTIALS="true"