Azure Load Balancer support for IP-based backend pool management is in preview

Azure Load Balancer now supports adding and removing resources from a backend pool via an IPv4 or IPv6 addresses and virtual network ID. This will enable you to easily manage the containers, virtual machines, and virtual machine scale sets associated with their load balancer. It will also allow IP addresses to be reserved as part of a backend pool before the associated resources are created.
Source: Azure Roadmap