I worked on PH infra for a few years - * The frontend itself runs on bare metal * A lot of the backend was built out as microservices, running on top of Mesos

I worked on PH infra for a few years - * The frontend itself runs on bare metal * A lot of the backend was built out as microservices, running on top of Mesos and then later K8s * CDN was in-house. The long tail is surprisingly long, but the front page videos were cached globally The unifying theme behind PH is that they host everything on their own equipment, no AWS/GCP involved.