Classify internal and external ip address

[abrarshivani]

vSphere Cloud Provider doesn't classify internal and external ip address appropriately. This creates problems when connecting the Kubernetes cluster from outside.

[abrarshivani]

In Kubernetes, external ip is defined as the ip which is accessible from other networks and internal ip is defined as the ip through which only nodes(vms) in cluster can communicate. To classify the ip addressees as external and internal, we need to get the information from vSphere Cloud Provider user about external and internal networks. There are two solutions:

1. Ask user for internal and external subnet in cloud config file and identify the interface in the VM which belongs to that subnet. Get the ip address of the interface and use that as internal/external ip.
2. Ask user for network labels (ex: VM Network) which corresponds to internal and external networks and get the ip that is assigned to the VM on this network by using VC apis. Use this ip as external/internal ip address.

Solution Analysis

1. User needs to provide subnet for external and internal networks. No need for Kubernetes node to talk to VC.
2. User needs to provide network name (ex: VM Network) for external and internal networks. or Kubernetes node needs to talk to the VC.

[divyenpatel]

Fix is made to set same internal and external ip for vSphere Cloud Provider.
kubernetes#45201

cc: @prashima