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cdk-eks-karpenter

This construct configures the necessary dependencies and installs Karpenter on an EKS cluster managed by AWS CDK.

Prerequisites

Usage with EC2 Spot Capacity

If you have not used EC2 spot in your AWS account before, follow the instructions here to create the service linked role in your account allowing Karpenter to provision EC2 Spot Capacity.

Using

In your CDK project, initialize a new Karpenter construct for your EKS cluster, like this:

const cluster = new Cluster(this, 'testCluster', {
  vpc: vpc,
  role: clusterRole,
  version: KubernetesVersion.V1_27,
  defaultCapacity: 1
});

const karpenter = new Karpenter(this, 'Karpenter', {
  cluster: cluster,
  namespace: "kube-system"
});

This will install and configure Karpenter in your cluster. To have Karpenter do something useful, you also need to create an EC2NodeClass and an NodePool, for a more complete example, see test/integ.karpenter.ts.

Known issues

It is now a best practice to install Karpenter into the kube-system namespace:

Kapenter CRD webhooks have 'kube-system' hard-coded into them, and do not work in other namespaces (such as 'karpenter')

Versions earlier than v0.6.1 fails to install

As of aws/karpenter#1145 the Karpenter Helm chart is refactored to specify clusterEndpoint and clusterName on the root level of the chart values, previously these values was specified under the key controller.

Testing

This construct adds a custom task to projen, so you can test a full deployment of an EKS cluster with Karpenter installed as specified in test/integ.karpenter.ts by running the following:

export CDK_DEFAULT_REGION=<aws region>
export CDK_DEFAULT_ACCOUNT=<account id>
npx projen test:deploy

As the above will create a cluster without EC2 capacity, with CoreDNS and Karpenter running as Fargate pods, you can test out the functionality of Karpenter by deploying an inflation deployment, which will spin up a number of pods that will trigger Karpenter creation of worker nodes:

kubectl apply -f test/inflater-deployment.yml

You can clean things up by deleting the deployment and the CDK test stack:

kubectl delete -f test/inflater-deployment.yml
npx projen test:destroy

FAQ

I'm not able to launch spot instances

  1. Ensure you have the appropriate linked role available in your account, for more details, see the karpenter documentation