Karpenter is an open-source, flexible, high-performance Kubernetes cluster autoscaler built with AWS. It helps improve your application availability and cluster efficiency by rapidly launching right-sized compute resources in response to changing application load. Karpenter also provides just-in-time compute resources to meet your application’s needs and will soon automatically optimize a cluster’s compute resource footprint to reduce costs and improve performance.
Before Karpenter, Kubernetes users needed to dynamically adjust the compute capacity of their clusters to support applications using Amazon EC2 Auto Scaling groups and the Kubernetes Cluster Autoscaler. Nearly half of Kubernetes customers on AWS report that configuring cluster auto scaling using the Kubernetes Cluster Autoscaler is challenging and restrictive.
When Karpenter is installed in your cluster, Karpenter observes the aggregate resource requests of unscheduled pods and makes decisions to launch new nodes and terminate them to reduce scheduling latencies and infrastructure costs. Karpenter does this by observing events within the Kubernetes cluster and then sending commands to the underlying cloud provider’s compute service, such as Amazon EC2.
It is an open-source project licensed under the Apache License 2.0. It is designed to work with any Kubernetes cluster running in any environment, including all major cloud providers and on-premises environments. Kapenter provisioners are designed to work alongside static capacity management solutions like Amazon EKS managed node groups and EC2 Auto Scaling groups. You may choose to manage the entirety of your capacity using provisioners, a mixed model with both dynamic and statically managed capacity, or a fully static approach. It is recommended not using Kubernetes Cluster Autoscaler at the same time as Karpenter because both systems scale up nodes in response to unschedulable pods. If configured together, both systems will race to launch or terminate instances for these pods.
Karpenter works with all kinds of Kubernetes applications, but it performs particularly well for use cases that require rapid provisioning and deprovisioning large numbers of diverse compute resources quickly. For example, this includes batch jobs to train machine learning models, run simulations, or perform complex financial calculations.