Installing a cluster on Azure using ARM templates

vCPU

40

20 per region

A default cluster requires 40 vCPUs, so you must increase the account limit.

By default, each cluster creates the following instances:

Because the bootstrap machine uses Standard_D4s_v3 machines, which use 4 vCPUs, the control plane machines use Standard_D8s_v3 virtual machines, which use 8 vCPUs, and the worker machines use Standard_D4s_v3 virtual machines, which use 4 vCPUs, a default cluster requires 40 vCPUs. The bootstrap node VM, which uses 4 vCPUs, is used only during installation.

To deploy more worker nodes, enable autoscaling, deploy large workloads, or use a different instance type, you must further increase the vCPU limit for your account to ensure that your cluster can deploy the machines that you require.

By default, the installation program distributes control plane and compute machines across all availability zones within a region. To ensure high availability for your cluster, select a region with at least three availability zones. If your region contains fewer than three availability zones, the installation program places more than one control plane machine in the available zones.

OS Disk

7

VM OS disk must be able to sustain a minimum throughput of 5000 IOPS / 200MBps. This throughput can be provided by having a minimum of 1 TiB Premium SSD (P30). In Azure, disk performance is directly dependent on SSD disk sizes, so to achieve the throughput supported by Standard_D8s_v3, or other similar machine types available, and the target of 5000 IOPS, at least a P30 disk is required.

Host caching must be set to ReadOnly for low read latency and high read IOPS and throughput. The reads performed from the cache, which is present either in the VM memory or in the local SSD disk, are much faster than the reads from the data disk, which is in the blob storage.

VNet

1

1000 per region

Each default cluster requires one Virtual Network (VNet), which contains two subnets.

Network interfaces

7

65,536 per region

Each default cluster requires seven network interfaces. If you create more machines or your deployed workloads create load balancers, your cluster uses more network interfaces.

Network security groups

2

5000

Each cluster creates network security groups for each subnet in the VNet. The default cluster creates network security groups for the control plane and for the compute node subnets:

Network load balancers

3

1000 per region

Each cluster creates the following load balancers:

If your applications create more Kubernetes LoadBalancer service objects, your cluster uses more load balancers.

Public IP addresses

3

Each of the two public load balancers uses a public IP address. The bootstrap machine also uses a public IP address so that you can SSH into the machine to troubleshoot issues during installation. The IP address for the bootstrap node is used only during installation.

Private IP addresses

7

The internal load balancer, each of the three control plane machines, and each of the three worker machines each use a private IP address.

Spot VM vCPUs (optional)

0

If you configure spot VMs, your cluster must have two spot VM vCPUs for every compute node.

20 per region

This is an optional component. To use spot VMs, you must increase the Azure default limit to at least twice the number of compute nodes in your cluster.