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Cluster Autoscaler

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Cluster Autoscaler with MNG

Overview

Cluster Autoscaler adjusts the size of your node group based on pending pods and resource requests.

Installation

# Add Helm repo
helm repo add cluster-autoscaler https://kubernetes.github.io/autoscaler
helm repo update
 
# Install Cluster Autoscaler
helm install cluster-autoscaler cluster-autoscaler/cluster-autoscaler \
  --namespace kube-system \
  --set awsRegion=us-west-2 \
  --set autoDiscovery.clusterName=my-cluster \
  --set expanders="least-waste,priority,skew"

Configuration for MNG

IAM policy for Cluster Autoscaler:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "autoscaling:DescribeAutoScalingGroups",
        "autoscaling:DescribeAutoScalingInstances",
        "autoscaling:DescribeLaunchConfigurations",
        "autoscaling:DescribeScalingActivities",
        "autoscaling:SetDesiredCapacity",
        "autoscaling:TerminateInstanceInAutoScalingGroup"
      ],
      "Resource": "*"
    }
  ]
}

Node Group Annotation

apiVersion: v1
kind: Node
metadata:
  annotations:
    eks.amazonaws.com/nodegroup: standard-workers
    cluster-autoscaler.kubernetes.io/safe-to-evict: "false"

Scale Down Behavior

# Configure scale-down delay in deployment
--set expandParams.scale-down-delay-after-add=10m
--set expandParams.scale-down-unneeded-time=10m
--set expandParams.scale-down-utilization-threshold=0.5

References

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