Cluster Autoscaler

Cluster Autoscaler - a component that automatically adjusts the size of a Kubernetes Cluster so that all pods have a place to run and there are no unneeded nodes.

Create IAM Policy

cluster-autoscaler-policy.json

{
    "Version": "2012-10-17",
    "Statement": [{
        "Effect": "Allow",
        "Action": [
            "autoscaling:DescribeAutoScalingGroups",
            "autoscaling:DescribeAutoScalingInstances",
            "autoscaling:DescribeLaunchConfigurations",
            "autoscaling:DescribeScalingActivities",
            "autoscaling:DescribeTags",
            "ec2:DescribeInstanceTypes",
            "ec2:DescribeLaunchTemplateVersions"
        ],
        "Resource": ["*"]
    },
    {
        "Effect": "Allow",
        "Action": [
            "autoscaling:SetDesiredCapacity",
            "autoscaling:TerminateInstanceInAutoScalingGroup",
            "ec2:DescribeImages",
            "ec2:GetInstanceTypesFromInstanceRequirements",
            "eks:DescribeNodegroup"
        ],
        "Resource": ["*"]
    }]
}

POLICY_ARN=$(aws iam create-policy \
    --policy-name AmazonEKSClusterAutoscalerPolicy \
    --policy-document file://cluster-autoscaler-policy.json \
    --query 'Policy.Arn' \
    --output text
)

Create ServiceAccount

eksctl utils associate-iam-oidc-provider --cluster=$CLUSTER_NAME --approve

eksctl create iamserviceaccount \
    --cluster=$CLUSTER_NAME \
    --namespace=kube-system \
    --name=cluster-autoscaler \
    --attach-policy-arn=$POLICY_ARN \
    --override-existing-serviceaccounts \
    --approve

Install with Helm

helm repo add autoscaler https://kubernetes.github.io/autoscaler
helm repo update autoscaler

helm install cluster-autoscaler autoscaler/cluster-autoscaler \
    --namespace kube-system \
    --set autoDiscovery.clusterName=$CLUSTER_NAME \
    --set awsRegion=$AWS_DEFAULT_REGION \
    --set cloudProvider=aws \
    --set extraArgs.logtostderr=true \
    --set extraArgs.stderrthreshold=info \
    --set extraArgs.v=4 \
    --set extraArgs.skip-nodes-with-local-storage=false \
    --set extraArgs.expander=least-waste \
    --set extraArgs.balance-similar-node-groups=true \
    --set extraArgs.skip-nodes-with-system-pods=false \
    --set rbac.serviceAccount.create=false \
    --set rbac.serviceAccount.name=cluster-autoscaler