Hostport Capability and FTP

The hostport capability was in older versions of Kubernetes, but it has been dropped in subsequent releases.

Kubenetes needs to use kubenet, rather the default cni, to support hostport. Flannel works with kubenet. Other Kubernetes networking models may support kubenet too, but only Flannel has been tested.

If you require FTP, you must enable hostport.

If you do not use FTP, then there is no need to enable hostport. If you use FTP, then each server in the cluster must install and configure Flannel.