OS that Shopify runs on

[casperm]

For one of our clients i need to know on which OS Shopify runs on (they need this for a contract with a financial software party). Now i'm not sure if there is a clear answer for this but if i could find out that would be great.

All i know is that Shopify uses Google Cloud Platform, and that it could be self-hosted if needed, but whether it uses Linux, Ubuntu, or even Windows i can't find out. Does anyone know this?