Karpenter: Tool for Autoscaling Kubernetes Clusters
Tags: kubernetes, devops, opensource, cloud
Published: 2022-12-29 15:25:23

Kubernetes has become the de facto standard for container orchestration, but one of the challenges of running a Kubernetes cluster is ensuring that it is properly scaled to meet the demands of your workloads. This is where Karpenter comes in.

## General Information
Karpenter is an open-source tool that automatically scales your Kubernetes cluster to meet the demands of your workloads. It works by monitoring the resource usage of your cluster and adding or removing nodes as needed to ensure that your applications have the resources they need to run smoothly.

Karpenter was developed by the team at OpenFaaS, a cloud native functions provider, and is designed to be easy to use and highly configurable. It can be run as a standalone tool or integrated into your existing Kubernetes cluster using the Kubernetes API.

## How It Works
Karpenter works by continuously monitoring the resource usage of your Kubernetes cluster and comparing it to the configured resource limits. When the resource usage of a cluster exceeds the limits, Karpenter will automatically add additional nodes to the cluster to meet the increased demand. Similarly, when the resource usage falls below the limits, Karpenter will remove nodes from the cluster to save on resources.

Karpenter uses a variety of metrics to determine the resource usage of your cluster, including CPU and memory usage, as well as custom metrics that you can define. This allows you to fine-tune the autoscaling behavior of your cluster to meet the specific needs of your workloads.


![How it works](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ahzsgvd2f4ms54189c3h.jpg)

## Benefits Compared to Cluster-Autoscaler
One of the main benefits of Karpenter is that it is designed to be highly configurable, which allows you to tailor the autoscaling behavior of your cluster to meet the specific needs of your workloads. This is in contrast to the cluster-autoscaler, which is a Kubernetes native tool that is more limited in terms of customization.

Another benefit of Karpenter is that it is designed to work with a wide range of cloud providers, including AWS, GCP, and Azure. This makes it a good choice for organizations that use multiple cloud providers or that want the flexibility to switch between providers.

Finally, Karpenter is an open-source tool, which means that it is continuously being improved and updated by a community of developers. This can make it a more reliable and up-to-date solution compared to proprietary autoscaling tools.

## How to Install Karpenter
Installing Karpenter is easy and can be done using a variety of methods. Here are a few options:

### Option 1: Install Using Helm
The easiest way to install Karpenter is using Helm, a package manager for Kubernetes. To install Karpenter using Helm, you will need to have Helm installed on your machine. If you don’t already have Helm installed, you can follow the installation instructions on the Helm website.

Once you have Helm installed, you can install Karpenter by running the following command:

```bash
helm install karpenter openfaas/karpenter
```
This will install Karpenter into your Kubernetes cluster and create all the necessary resources, including a Deployment and a Service.

### Option 2: Install Manually Using YAML Files
If you prefer to install Karpenter manually, you can use the provided YAML files to create the necessary resources in your Kubernetes cluster. To do this, you will need to have the kubectl command-line tool installed on your machine. If you don’t already have kubectl installed, you can follow the installation instructions on the Kubernetes website.

Once you have kubectl installed, you can use the following command to create the Karpenter Deployment and Service:
```bash
kubectl apply -f https://raw.githubusercontent.com/openfaas/karpenter/main/yaml/karpenter.yaml
```
This will create a Deployment and a Service for Karpenter in your cluster.

### Option 3: Install Using Docker
If you prefer to run Karpenter as a standalone tool, you can install it using Docker. To do this, you will need to have Docker installed on your machine. If you don’t already have Docker installed, you can follow the installation instructions on the Docker website.

Once you have Docker installed, you can pull the Karpenter image from Docker Hub using the following command:

```bash
docker pull openfaas/karpenter
```
Then, you can run the Karpenter container using the following command:

```bash
docker run -d --name karpenter openfaas/karpenter
```
This will run Karpenter as a daemon in a Docker container.

## Conclusion
Karpenter is a powerful and flexible tool for autoscaling your Kubernetes cluster to meet the demands of your workloads. Whether you want to run it as a standalone tool or integrate it into your existing cluster, Karpenter offers a range of installation options to suit your needs. Give it a try and see how it can help you optimize the performance and resource utilization of your Kubernetes cluster.

## About author

Artsiom Hontar is a software engineer, AWS solution architect and Kubernetes admin certified. Hosting [blog](https://solutionarchitectureblog.com/) about software engineering and related stuff.