https://techcrunch.com/2019/11/22/cloud-foundrys-kubernetes-bet-with-project-eirini-hits-1-0/

Cloud Foundry, the open-source platform-as-a-service that, with the help of lots of commercial backers, is currently in use by the majority of Fortune 500 companies, launched well before containers, and especially the Kubernetes orchestrator, were a thing. Instead, the project built its own container service, but the rise of Kubernetes obviously created a lot of interest in using it for managing Cloud Foundry’s container implementation. To do so, the organization launched Project Eirini last year; today, it’s officially launching version 1.0, which means it’s ready for production usage.

Eirini/Kubernetes doesn’t replace the old architecture. Instead, for the foreseeable future, they will operate side-by-side, with the operators deciding on which one to use.