Introducing KWOK: Kubernetes WithOut Kubelet

2023-02-28 21:04:07

Wednesday, March 01, 2023

Creator: Shiming Zhang (DaoCloud), Wei Huang (Apple), Yibo Zhuang (Apple)

Have you ever ever puzzled learn how to arrange a cluster of hundreds of nodes simply in seconds, learn how to simulate actual nodes with a low useful resource footprint, and learn how to check your Kubernetes controller at scale with out spending a lot on infrastructure?

Should you answered “sure” to any of those questions, then you definitely is likely to be eager about KWOK, a toolkit that lets you create a cluster of hundreds of nodes in seconds.

What’s KWOK?

KWOK stands for Kubernetes WithOut Kubelet. To date, it offers two instruments:

kwok: kwok is the cornerstone of this mission, answerable for simulating the lifecycle of faux nodes, pods, and different Kubernetes API assets.
kwokctl: kwokctl is a CLI device designed to streamline the creation and administration of clusters, with nodes simulated by kwok.

Why use KWOK?

KWOK has a number of benefits:

Velocity: You possibly can create and delete clusters and nodes nearly immediately, with out ready for boot or provisioning.
Compatibility: KWOK works with any instruments or shoppers which might be compliant with Kubernetes APIs, similar to kubectl, helm, kui, and so on.
Portability: KWOK has no particular {hardware} or software program necessities. You possibly can run it utilizing pre-built photographs, as soon as Docker or Nerdctl is put in. Alternatively, binaries are additionally obtainable for all platforms and could be simply put in.
Flexibility: You possibly can configure totally different node varieties, labels, taints, capacities, situations, and so on., and you may configure totally different pod behaviors, standing, and so on. to check totally different situations and edge instances.
Efficiency: You possibly can simulate hundreds of nodes in your laptop computer with out important consumption of CPU or reminiscence assets.

What are the use instances?

KWOK can be utilized for varied functions:

Studying: You should use KWOK to study Kubernetes ideas and options with out worrying about useful resource waste or different penalties.
Improvement: You should use KWOK to develop new options or instruments for Kubernetes with out accessing to an actual cluster or requiring different elements.
Testing:
- You possibly can measure how nicely your utility or controller scales with totally different numbers of nodes and(or) pods.
- You possibly can generate excessive hundreds in your cluster by creating many pods or providers with totally different useful resource requests or limits.
- You possibly can simulate node failures or community partitions by altering node situations or randomly deleting nodes.
- You possibly can check how your controller interacts with different elements or options of Kubernetes by enabling totally different characteristic gates or API variations.

What are the constraints?

KWOK is just not supposed to exchange others fully. It has some limitations that try to be conscious of:

Performance: KWOK is just not a kubelet and will exhibit totally different behaviors in areas similar to pod lifecycle administration, quantity mounting, and gadget plugins. Its major perform is to simulate updates of node and pod standing.
Accuracy: It’s necessary to notice that KWOK doesn’t precisely replicate the efficiency or conduct of actual nodes below varied workloads or environments. As a substitute, it approximates some behaviors utilizing easy formulation.
Safety: KWOK doesn’t implement any safety insurance policies or mechanisms on simulated nodes. It assumes that each one requests from the kube-apiserver are approved and legitimate.