code: func (a AzureClient) GetPrivateIPAddress(resourceGroup, name string) (string, error) {
  	f := logutil.Fields{"name": name}
  	log.Debug("Querying network interface.", f)
  	nic, err := a.networkInterfacesClient().Get(resourceGroup, name, "")
  	if err != nil {
  		return "", err
  	}
  	if nic.Properties == nil || nic.Properties.IPConfigurations == nil ||
  		len(*nic.Properties.IPConfigurations) == 0 {
  		log.Debug("No IPConfigurations found on NIC", f)
  		return "", nil
  	}
  	return to.String((*nic.Properties.IPConfigurations)[0].Properties.PrivateIPAddress), nil
  }
docs: // GetPrivateIPAddress attempts to retrieve private IP address of the specified
  // network interface name.  If IP address is not allocated yet, returns empty
  // string.