code: func (ss *scaleSet) getPrimaryNetworkInterfaceConfiguration(networkConfigurations []compute.VirtualMachineScaleSetNetworkConfiguration, nodeName string) (*compute.VirtualMachineScaleSetNetworkConfiguration, error) {
  	if len(networkConfigurations) == 1 {
  		return &networkConfigurations[0], nil
  	}
  
  	for idx := range networkConfigurations {
  		networkConfig := &networkConfigurations[idx]
  		if networkConfig.Primary != nil && *networkConfig.Primary == true {
  			return networkConfig, nil
  		}
  	}
  
  	return nil, fmt.Errorf("failed to find a primary network configuration for the scale set VM %q", nodeName)
  }
docs: // getPrimaryNetworkInterfaceConfiguration gets primary network interface configuration for scale set virtual machine.