etcd configuration

EKS Anywhere cluster yaml etcd specification reference

There are two types of etcd topologies for configuring a Kubernetes cluster:

  • Stacked: The etcd members and control plane components are colocated (run on the same node/machines)
  • Unstacked/External: With the unstacked or external etcd topology, etcd members have dedicated machines and are not colocated with control plane components

The unstacked etcd topology is recommended for a HA cluster for the following reasons:

  • External etcd topology decouples the control plane components and etcd member. So if a control plane-only node fails, or if there is a memory leak in a component like kube-apiserver, it won’t directly impact an etcd member.
  • Etcd is resource intensive, so it is safer to have dedicated nodes for etcd, since it could use more disk space or higher bandwidth. Having a separate etcd cluster for these reasons could ensure a more resilient HA setup.

EKS Anywhere supports both topologies. In order to configure a cluster with the unstacked/external etcd topology, you need to configure your cluster by updating the configuration file before creating the cluster. This is a generic template with detailed descriptions below for reference:

apiVersion: anywhere.eks.amazonaws.com/v1alpha1
kind: Cluster
metadata:
   name: my-cluster-name
spec:
   clusterNetwork:
      pods:
         cidrBlocks:
            - 192.168.0.0/16
      services:
         cidrBlocks:
            - 10.96.0.0/12
      cni: "cilium"
   controlPlaneConfiguration:
      count: 1
      endpoint:
         host: ""
      machineGroupRef:
         kind: VSphereMachineConfig
         name: my-cluster-name-cp
   datacenterRef:
      kind: VSphereDatacenterConfig
      name: my-cluster-name
   # etcd configuration
   externalEtcdConfiguration:
      count: 3
      machineGroupRef:
        kind: VSphereMachineConfig
        name: my-cluster-name-etcd
   kubernetesVersion: "1.19"
   workerNodeGroupConfigurations:
      - count: 1
        machineGroupRef:
           kind: VSphereMachineConfig
           name: my-cluster-name

externalEtcdConfiguration (under Cluster)

This field accepts any configuration parameters for running external etcd.

count (required)

This determines the number of etcd members in the cluster. The recommended number is 3.

machineGroupRef (required)

Refers to the Kubernetes object with vsphere specific configuration for your etcd members. See VSphereMachineConfig Fields