The document discusses scaling Kubernetes and custom resources. It notes that the Kubernetes API server does not scale well and is a single point of failure. Managing millions of custom resources requires infinite resources. Some clients may not tolerate large datasets or timeouts. The API server can be overloaded by unfiltered list operations. Scaling to support a large number of custom resources requires a complex architecture with custom components and business logic, as well as mechanisms like object reconciliation pauses and caching.