KWOK: Revolutionize Your Kubernetes Testing in Seconds!

Have you ever wondered how to set up a cluster of thousands of nodes in seconds, simulate real nodes with low resource requirements, and test your Kubernetes controllers at scale without spending much on infrastructure?

If you answered “Yes” to any of these questions, KWOK might be just what you need. It’s a toolkit that allows you to create a cluster of thousands of nodes in seconds.

What is KWOK?

KWOK stands for Kubernetes WithOut Kubelet. Currently, it offers two main tools:

kwok: kwok is the core of this project and is responsible for simulating the lifecycle of fake nodes, pods, and other Kubernetes API resources.
kwokctl: kwokctl is a CLI tool that simplifies the creation and management of clusters with nodes simulated by kwok.

Why use KWOK?

KWOK offers several advantages:

Speed: You can create and delete clusters and nodes almost instantly, without waiting for booting or provisioning.
Compatibility: KWOK works with all tools or clients compatible with Kubernetes APIs, like kubectl, helm, kui, etc.
Portability: KWOK has no special hardware or software requirements. You can run it with pre-built images once Docker or Nerdctl is installed. Alternatively, binaries are available for all platforms and can be easily installed.
Flexibility: You can configure different node types, labels, taints, capacities, conditions, etc., and set different pod behaviors and statuses to test various scenarios and edge cases.
Performance: You can simulate thousands of nodes on your laptop without consuming significant CPU or memory resources.

Use Cases

KWOK can be used for various purposes:

Learning: You can use KWOK to learn the concepts and features of Kubernetes without worrying about resource wastage or other consequences.
Development: With KWOK, you can develop new features or tools for Kubernetes without access to a real cluster or needing other components.
Testing:
- You can measure how well your application or controller scales with different numbers of nodes and/or pods.
- You can generate high loads on your cluster by creating many pods or services with different resource requests or limits.
- You can simulate node failures or network partitions by changing node conditions or randomly deleting nodes.
- You can test how your controller interacts with other components or features of Kubernetes by enabling different feature gates or API versions.

Limitations

KWOK is not intended to fully replace others. There are some limitations you should be aware of:

Functionality: KWOK is not a kubelet and may exhibit different behaviors in areas like pod lifecycle management, volume mounting, and handling device plugins. Its main function is to simulate updates of node and pod statuses.
Accuracy: It’s important to note that KWOK does not accurately reflect the performance or behavior of real nodes under different workloads or environments. Instead, some behaviors are approximated with simple formulas.
Security: KWOK does not enforce security policies or mechanisms on simulated nodes. It assumes all requests from the kube-apiserver are authorized and valid.