portName

A named port on a backend instance group representing the port for communication to the backend VMs in that group. Required when the loadBalancingScheme is EXTERNAL, EXTERNAL_MANAGED, INTERNAL_MANAGED, or INTERNAL_SELF_MANAGED and the backends are instance groups. The named port must be defined on each backend instance group. This parameter has no meaning if the backends are NEGs. API sets a default of "http" if not given. Must be omitted when the loadBalancingScheme is INTERNAL (Internal TCP/UDP Load Balancing).