API Server Endpoint

This document describes how to configure your clusters’ api server load balancer and IP.

Load Balancer Type

CAPZ supports two load balancer types, Public and Internal.

Public, which is also the default, means that your API Server Load Balancer will have a publicly accessible IP address. This Load Balancer type supports a “public cluster” configuration, which load balances internet source traffic to the apiserver across the cluster’s control plane nodes.

Internal means that the API Server endpoint will only be accessible from within the cluster’s virtual network (or peered VNets). This configuration supports a “private cluster” configuration, which load balances internal VNET source traffic to the apiserver across the cluster’s control plane nodes.

For a more complete “private cluster” template example, you may refer to this reference template that the capz project maintains.

For more information on Azure load balancing, see Load Balancer documentation.

Here is an example of configuring the API Server LB type:

apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: AzureCluster
metadata:
  name: my-private-cluster
  namespace: default
spec:
  location: eastus
  networkSpec:
    apiServerLB:
      type: Internal

Private IP

When using an api server load balancer of type Internal, the default private IP address associated with that load balancer will be 10.0.0.100. If also specifying a custom virtual network, make sure you provide a private IP address that is in the range of your control plane subnet and not in use.

For example:

apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: AzureCluster
metadata:
  name: my-private-cluster
  namespace: default
spec:
  location: eastus
  networkSpec:
    vnet:
      name: my-vnet
      cidrBlocks:
        - 172.16.0.0/16
    subnets:
      - name: my-subnet-cp
        role: control-plane
        cidrBlocks:
          - 172.16.0.0/24
      - name: my-subnet-node
        role: node
        cidrBlocks:
          - 172.16.2.0/24
    apiServerLB:
      type: Internal
      frontendIPs:
        - name: lb-private-ip-frontend
          privateIP: 172.16.0.100

Public IP

When using an api server load balancer of type Public, a dynamic public IP address will be created, along with a unique FQDN.

You can also choose to provide your own public api server IP. To do so, specify the existing public IP as follows:

apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: AzureCluster
metadata:
  name: my-cluster
  namespace: default
spec:
  location: eastus
  networkSpec:
    apiServerLB:
      type: Public
      frontendIPs:
        - name: lb-public-ip-frontend
          publicIP:
            name: my-public-ip
            dns: my-cluster-986b4408.eastus.cloudapp.azure.com

Note that dns is the FQDN associated to your public IP address (look for “DNS name” in the Azure Portal).

When you BYO api server IP, CAPZ does not manage its lifecycle, ie. the IP will not get deleted as part of cluster deletion.

Load Balancer SKU

At this time, CAPZ only supports Azure Standard Load Balancers. See SKU comparison for more information on Azure Load Balancers SKUs.