Virtual Machine Scale Sets
Virtual Machine Scale Sets allow deploying and managing multiple virtual machines as one, representing a set of a identically-configured machines.
VMs can be fronted with either application gateway or load balancer. Direct access to VMs can be allowed via NAT rules (at port 50,000 and above) for LBs, which is not supported on application gateway.
Scale out (and back in) operations can either be scheduled in advance for known periods of higher traffic volume, or left to metric-based changes. VMSS can scale up to 1,000 instances.
VMSS supports availability zones, though it's not possible to combine AZs with unmanaged disks.
Non-essential or fault-tolerant workloads can request low-priority instances. Support for spot instance pricing is in preview.