If you’re interviewing for a role in DevOps, software engineering, or cloud computing, chances are you’ll want to prepare for Kubernetes interview questions. Since Kubernetes is commonly used by professionals in these positions, hiring managers want to get a sense of your knowledge and experience with Kubernetes to ensure you’ll be successful in the role.
One of the best ways to prepare for challenging interview questions is to set up a mock interview. You can ask someone to play the role of the interviewer and read off questions from a list you put together. This gives you the opportunity to practice answering questions out loud in front of another person. If you’re interviewing over Zoom, try to do your mock interview over Zoom too. That way, you can practice interviewing virtually as well.
And if you’d rather practice by yourself, you can record yourself using Zoom, and then play back the video to see how you did and find areas that you’d like to work on.
To help you prepare, here are 15 Kubernetes interview questions, along with tips on how to answer them.
1. What is Kubernetes, and what does it do?
Your interview will likely begin with one or two ice-breaker questions. This is a nice way to ease into the interview before the more difficult questions. Depending on the ice-breaker, you may also be able to weave in details about a project you’re proud of or a recent accomplishment.
In your answer to this question, you can mention that Kubernetes (coo-ber-NEH-tees), also written as K8s, is a portable, open-source container orchestration system originally designed by Google. Kubernetes works with other platforms like Docker, which creates and packages containers. Kubernetes then manages groups of containers at runtime.
2. What is container orchestration?
Container orchestration automates how containers run — this includes provisioning, deployment, scaling, load balancing, and lifecycle management of containers. Containers are applications, software packages, or services that are packaged and deployed in a stand-alone unit that includes everything needed to run the software: code, settings, libraries, and other dependencies.
Container orchestration is especially important when running multiple, complex containerized applications that themselves depend on containerized applications to function.
3. What’s the difference between Kubernetes and Docker?
Kubernetes and Docker perform different but complementary functions. Docker is a containerization platform that allows you to package application files into a unit called a container. Docker containers hold everything needed to run an application, including source code, settings, operating system libraries, and other dependencies. When you run a containerized application, Kubernetes then manages the container, including resource allocation and deployment.
In other words, Docker provides the containers, and Kubernetes ensures that the containers are always running correctly.
4. What are the advantages of Kubernetes?
When answering this question, it’s recommended that you cite the advantages or features that you’ve leveraged in your own work. Using personal projects or work experience as a starting point allows you to elaborate on your expertise and use concrete details to explain your key points. Here are a few ideas to help you craft your response to this question:
- Kubernetes is flexible enough to run on physical, local servers, private clouds, or public clouds like Google, Azure, and AWS.
- Kubernetes is open source.
- Kubernetes is now a widely used and proven tool.
5. What are the main features of Kubernetes?
Similar to the above, you may want to discuss a few of the main features of Kubernetes that you know best based on your past work. If you’re really familiar with automated scheduling, you can mention how you’ve used this feature a lot on projects. Or maybe load balancing and horizontal scaling has been crucial in past projects. A few other features that you can consider discussing include enterprise-ready capabilities, auto-scalable infrastructure, and automatic redeployment/self-healing.
6. What’s a Kubernetes Pod?
A Pod is a group of one or more containers that share storage, resources, and a specification to run containers within the Pod. Pods are the most basic types of Kubernetes objects. Kubernetes doesn’t manage containers directly but rather manages Pods.
7. How do you control the resource usage of a Pod?
You can control the resource usage of a Kubernetes Pod by using requests and limits. In this context, a request refers to the number of resources requested for a particular container. If a container exceeds its request, it can be throttled back to match the request.
A limit is a cap on the resources that a single container can utilize. If a container goes over this defined limit, Kubernetes can terminate it to help another container that needs the extra resources.
8. What’s a node?
Kubernetes Pods run on nodes, which are machines or computer hardware that contain the necessary services to run a Pod. A node can be a physical machine or a virtual machine. Since nodes have limited resources and capacities, Kubernetes nodes are managed by control planes, which automate the scheduling and deployment of Pods that depend on the node to run.
Typically, containerized applications run on several nodes, which are grouped in a Kubernetes cluster. A node cluster can consist of a combination of physical machines, virtual machines, local servers, and cloud-based servers.
Kubernetes nodes contain three main components: a kubelet, a container runtime, and a kube-proxy.
9. What’s a kubelet?
A kubelet (coob-let) is an agent that runs on each node of a cluster. Kubelets ensure that containers are properly running within a Pod. Every kubelet works with a set of instructions, or PodSpecs, that specify which containers should be running within a Pod.
10. What’s container runtime?
The container runtime is the software that runs the containers. Kubernetes doesn’t directly run containers but rather supports container runtimes such as Docker, containerd, and CRI-O. Kubernetes then instructs the container runtime what to do and when to do it.
11. What’s kube-proxy?
Kube-proxy is a type of network proxy that manages network rules and directs traffic on each node of a cluster. These rules apply to communication between different Pods, such as resource and load-balance requests.
12. What’s Kubectl?
Kubectl (coob-control) is a command-line tool for Kubernetes and allows developers to run commands on Kubernetes clusters. Using kubectl, it’s possible to deploy applications, view logs, and inspect and manage resources for the cluster.
13. What’s Minikube?
Minikube (mini-coob) is a utility that allows you to run Kubernetes locally on a personal computer running on Windows, macOS, or Linux. Minikube is configured to run on a single node contained in a virtual machine so that you can test out Kubernetes or use it for daily development tasks.
14. What’s Heapster?
Heapster aggregates performance, monitoring, and event data from Kubernetes clusters. Heapster is set up as a Pod within a cluster and queries information from Kubelets on other Pods in the cluster. Heapster then gathers and labels the information for storage, analysis, and data visualization.
15. What can be done to increase Kubernetes security?
One of the main disadvantages of Kubernetes is that containers and Pods are distributed across many locations, both on local machines and in the cloud. And since Pods constantly communicate with each other, a single compromised Pod can pose a security risk for the entire system.
By default, a Kubernetes Pod can communicate with any other Pod, but there are ways to limit this, including:
- Utilizing role-based access control (RBAC) to narrow permissions
- Establishing security boundaries with namespaces
- Enabling audit logging
Get more interview help to ace your Kubernetes interview
If you’re looking for other ways to practice for your upcoming interview, check out our complete guide to acing the technical interview and our advice for answering behavioral interview questions. We also have helpful tips for the whiteboard interview that you can review.
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