Azure Kubernetes Service(AKS) recently offers spot node pool feature as preview - 4/30/2020 right now. This feature enable Azure developers to reduce VM costs by using spot VMs for AKS clusters.
Refer to Preview - Add a spot node pool to an Azure Kubernetes Service (AKS) cluster - Azure Kubernetes Service | Microsoft Docs. Here is a sample command to execute on Azure Portal, but you need to enable this preview feature by following the article before running commands below. You can execute this command successfully.
az aks nodepool add \ --resource-group YOUR-RESOURCE-GROUP \ --cluster-name YOUR-AKS-CLUSTER-NAME \ --name spotnode01 \ --priority Spot \ --node-vm-size Standard_DS2_v2 \ --node-count 1 \ --eviction-policy Delete \ --spot-max-price -1 \ --no-wait
I guess you also want to save cost by using burstable instances named "B series". You can execute a command to specify B series instances but it will be failed .
az aks nodepool add \ --resource-group YOUR-RESOURCE-GROUP \ --cluster-name YOUR-AKS-CLUSTER-NAME \ --name spotnode02 \ --priority Spot \ --node-vm-size Standard_B2ms \ --node-count 1 \ --eviction-policy Delete \ --spot-max-price -1 \ --no-wait
Here is a screenshot for commands above. You can execute commands to add node pools by using spot VMS, but provisions will fail.
This is limitation of spot VMs. Refer to Use Azure Spot VMs - Azure Windows Virtual Machines | Microsoft Docs. B-series and Promo versions of any size (like Dv2, NV, NC, H promo sizes) are not supported at this time.