Feature Overview (aka. Goal Summary)  

As cluster admin I would like to configure machinesets to allocate instances from pre-existing Capacity Reservation in Azure.
I want to create a pool of reserved resources that can be shared between clusters of different teams based on their priorities. I want this pool of resources to remain available for my company and not get allocated to another Azure customer.

https://docs.microsoft.com/en-us/azure/virtual-machines/capacity-reservation-associate-vm?tabs=api1%2Capi2%2Capi3

Additional background on the feature for considering additional use cases

https://techcommunity.microsoft.com/t5/azure-compute-blog/guarantee-capacity-access-with-on-demand-capacity-reservations/ba-p/3269202