Does anyone know how platforms like Katacoda are able to provision environments so quickly and to large number of people?

I have seen many e-learning sources leverage Katacoda to create customised labs that people have lifelong access to. Wanted to understand how they are able to provide VMs, what could be the backend architecture. Is there any open source project similar to this?

submitted by /u/rhaegalInRed
[link] [comments]