This guide describes how you could use Google Cloud Storage as an origin server.  

Create a Google Cloud Storage (GCS) bucket.

Upload your data and mark it as Shared publicly.

Login to the G-CORE control panel at our site and create a Resource using storage.googleapis.com as origin.

When your CDN-Resource is created, check the accessibility of files through CDN. Ensure that your CNAME record has been configured in a proper way before using it for integration.

(i) If you want to hide your cloud bucket name, use our Rewrite option.

Integration has been completed! We highly recommend you to check the HTML code of your web page to ensure that URLs have been rewritten properly from your original ones to CNAME from the control panel.

To do that press F12 or open Developers Tools in your browser, choose the Network tab and refresh the page. All static files should have your CNAME in URLs.