Kubernetes Interview Questions And Answers

How To Nail Your Next Tech Interview

Kubernetes or K8s is an open-source container orchestration system designed by Google. It is used for automating software deployment, scaling, and management. While Google designed it initially, the Cloud Native Computing Foundation maintains the project now. This article discusses Kubernetes interview questions to help you with your interview preparation.

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In this article, weâll cover:

• Kubernetes Interview Questions and Answers
• Basic Kubernetes Interview Questions
• Kubernetes Interview Questions for Experienced Developers
• Kubernetes Interview Questions for DevOps
• FAQs on Kubernetes Interview Questions

What Is The Ingress Network And How Does It Work

An ingress is an object that allows users to access your Kubernetes services from outside the Kubernetes cluster. Users can configure the access by creating rules that define which inbound connections reach which services.

How does it work- This is an API object that provides the routing rules to manage the external users’ access to the services in the Kubernetes cluster through HTTPS/ HTTP. With this, users can easily set up the rules for routing traffic without creating a bunch of load balancers or exposing each service to the nodes.

What Are The Main Differences Between The Docker Swarm And Kubernetes

Docker Swarm is Dockers native, open-source container orchestration platform that is used to cluster and schedule Docker containers. Swarm differs from Kubernetes in the following ways:

• Docker Swarm is more convenient to set up but doesnt have a robust cluster, while Kubernetes is more complicated to set up but the benefit of having the assurance of a robust cluster
• Docker Swarm cant do auto-scaling however, Docker scaling is five times faster than Kubernetes
• Docker Swarm doesnt have a GUI Kubernetes has a GUI in the form of a dashboard
• Docker Swarm does automatic load balancing of traffic between containers in a cluster, while Kubernetes requires manual intervention for load balancing such traffic
• Docker requires third-party tools like ELK stack for logging and monitoring, while Kubernetes has integrated tools for the same
• Docker Swarm can share storage volumes with any container easily, while Kubernetes can only share storage volumes with containers in the same pod
• Docker can deploy rolling updates but cant deploy automatic rollbacks Kubernetes can deploy rolling updates as well as automatic rollbacks

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What Are The Architecture Layers Of Kubernetes

The Kubernetes architecture has three main layers. The upper level abstracts the complexities of the lower layer. The image below illustrates the different layers:

At this layer, Kubernetes makes a cluster of host storage resources and networking that helps run various workloads of the system. These clusters group several machines into a single unit.

Every machine available in a cluster is allocated a specific role. The master is the control plane responsible for carrying out activities, like authorization, authentication, and scheduling the pods at the cluster level. The main components of the master are the API server, scheduler, and controller manager.

• Application Layer:

Kubernetes itself is a complicated distributed system running on an API approach. You need to submit a plan in a YAML or JSON format whenever you wish to run an application. The master server goes through the submitted plan and checks the requirements and current state of the cluster.

Later, users interact with the cluster using the API ecosystem. The scheduler and controller manager manage the functioning of the cluster, and workers do their job to produce the output.

Q How Can We Enable Monitoring Of The Pods

To monitor the pods running on the cluster, we can use the following command to check their utilization:

kubectl top pods -n < namespace> 

Pod-level metrics can be viewed using the Grafana dashboard as well. Prometheus and Grafana need to be integrated with the metrics that are exposed by Kubernetes. Kubernetes exposes several metrics that are related to overall cluster health as well as pod-level metrics. The metrics server is responsible for exposing these metrics. These metrics can be accessed using /metrics API.

kubectl get --raw /metrics

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Common Kubernetes Interview Questions And Answers

Question: Why do companies use Kubernetes?Companies use Kubernetes to manage orchestration and IT workloads with high efficiency.

Question: Explain the top features of KubernetesTop features of Kubernetes include:

Question: Explain Kubernetes clusters.Kubernetes clusters are a set of node machines that run containerized applications.

Questions: Explain the role of Kubernetes Network PolicyKubernetes network policy defines how pods within a namespace would communicate with other pods and with the network.

Question: What is Kubectl?Kubectl is a command line tool that you can use to interact with Kubernetes API servers from a terminal. Kubectl = Kube Control CLI.

Question: Explain what a node is in Kubernetes.Nodes are a collection of resources within Kubernetes that support container. Depending upon the Kubernetes cluster, a node can be a physical machine or a virtual machine.

Question: How do you check the status of a Kubernetes deployment?To check the status of a deployed K8, run the following command:

kubectl rollout status

Once you run this, you should see the following in your command prompt:NAME READY UP-TO-DATE AVAILABLE AGEname-of-deployment 0/3 0 0 6s

Question: How do you run Kubernetes locally?To run Kubernetes locally, we can use Minikube.

Question: What are the different types of controller managers in Kubernetes?Different types of controller managers in Kubernetes are:

• Token controller

Q1 What Is Kubernetes

Kubernetes is an open-source container orchestration system for deploying, scaling, and managing automated applications. It offers an excellent community and works with all cloud providers. Hence, it is a multi-container management solution.

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Q What Is A Node In Kubernetes

A node is the smallest fundamental unit of computing hardware. It represents a single machine in a cluster, which could be a physical machine in a data center or a virtual machine from a cloud provider. Each machine can substitute any other machine in a Kubernetes cluster. The master in Kubernetes controls the nodes that have containers.

What Does A Cluster Of Containers In Kubernetes Mean

A cluster is a group of containers or machines, while a container is a tool that hosts the Application Programming Interface server. Recruiters may ask this question to gauge your understanding of containers and clusters. Define each element, describe their functioning and show the relationships between them.

Example:’A cluster is a collection of containers or a group of machine elements that form the nodes. Clusters in Kubernetes initiate routes that enable containers within the node to communicate with each other. Kubernetes is an orchestrator that schedules containers within a cluster’.

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Q How Do You Configure Resource Limits For The Sidecar Container Pattern

Configuring resource limits is very important when it comes to Sidecar containers. The main point we need to understand here is All the containers run in parallel so when you configure resource limits for the pod you have to take that into consideration.

• The sum of all the resource limits of the main containers as well as sidecar containers

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Can You Explain The Differences Between Docker Swarm And Kubernetes

Below are the main difference between Kubernetes and Docker:

• The installation procedure of the K8s is very complicated but if it is once installed then the cluster is robust. On the other hand, the Docker swarm installation process is very simple but the cluster is not at all robust.
• Kubernetes can process the auto-scaling but the Docker swarm cannot process the auto-scaling of the pods based on incoming load.
• Kubernetes is a full-fledged Framework. Since it maintains the cluster states more consistently so autoscaling is not as fast as Docker Swarm.

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Kubernetes Interview Questions & Answers

1. What is Kubernetes?Answer: Kubernetes is an open-source container orchestration platform. It was developed by Google and was donated to the Cloud Native Computing Foundation in 2015.

2. How does Kubernetes relate to Docker?Answer: Docker is a container runtime which is a software that runs containerized applications. When Kubernetes schedules a pod to a node, the kubelet running on that node instructs Docker to launch the containers.

3. What is container orchestration?Answer: Container orchestration is the automation of components and processes related to running containers. It includes things like configuring and scheduling containers, the availability of containers, allocation of resources between containers, and securing the interaction between containers, among other things.

4. How is Kubernetes related to Docker?Answer: Its a known fact for all of us that Docker used to provide the lifecycle management of containers and a Docker image helps in building the runtime containers. But, since these individual containers have to communicate, Kubernetes is used. So, Docker helps in building the containers and these containers help in communicating with each other via Kubernetes. So, containers running on the multiple hosts can be manually linked and orchestrated by making use of Kubernetes.

5. What do you know about Kubernetes clusters?Answer: A Kubernetes cluster is a set of nodes that containerized applications run on. These nodes can be physical or virtual machines.

What Is Orchestration When It Comes To Software And Devops

Orchestration refers to the integration of multiple services that allows them to automate processes or synchronize information in a timely fashion. Say, for example, you have six or seven microservices for an application to run. If you place them in separate containers, this would inevitably create obstacles for communication. Orchestration would help in such a situation by enabling all services in individual containers to work seamlessly to accomplish a single goal.

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What The Following In The Deployment Configuration File Mean

spec:  containers:    - name: USER_PASSWORD      valueFrom:        secretKeyRef:          name: some-secret          key: password

Explanation –

USER_PASSWORD environment variable will store the value from the password key in the secret called “some-secret” In other words, you reference a value from a Kubernetes Secret.

What Are The Components Of Kubernetes Cluster

A Kubernetes cluster contains six main components

• API server It works as the front end of the control panel of Kubernetes.
• Scheduler This schedules nodes as per their resource needs. It schedules a POD to a compute node according to its resource requirements.
• Controller manager Handles node controllers, replication controllers and endpoint controllers. It ensures that the correct number of PODS are running.
• Kubelet Communicates with the Docker engine and ensures that containers are running in a Pod. It interacts with the Control plane when to execute an action.
• Kube–proxy This is a network proxy that facilitates Kubernetes networking. Implements the Kubernetes Service concept across every node in a given cluster.
• Etcd Stores cluster data such as state information and configuration information.

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What Are Masters In Kubernetes

Master is considered the central control point, providing the unified view of a cluster. A single master node is responsible for controlling multiple minions. Master servers work together to accept user requests, specify the best possible way for scheduling workload containers, and authenticate clients and nodes. Also, the master can adjust cluster-wide networking and manage scaling and health checks of clusters.

What Is Rbac And How Does It Relate To Kubernetes

Role-based access control is the technique by which one creates Kubernetes Roles and RoleBindings. A Kubernetes Role is an abstraction that defines a relationship between a Kubernetes resource and action for example, can create a pod where pod is the Kubernetes resource and create is the action. A RoleBinding maps a particular user or service to a particular Role.

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Q What Is Required To Deploy A Simple Application Like A Web Server In Kubernetes

You can run an application by creating a Kubernetes Deployment object, and you can describe a Deployment in a YAML file. For example, this YAML file nginx-deployment.yaml describes a Deployment that runs the nginx:31871:

apiVersion: apps/v1kind: Deploymentmetadata:name: nginxlabels:app: nginxspec:replicas: 1selector:matchLabels:app: nginxtemplate:metadata:labels:app: nginxspec:containers:      - name: nginximage: nginxports:        - containerPort: 80

Create the deployment with following command

kubectl create -f nginx-deployment.yaml

The above command will create one pod with single NGINX container. The NGINX web server will start listening on port 80. Since the replicas is specified as 1 it will create only single pod for service to expose.

Check the deployment and pod is created successfully.

root@ubuntu-s-1vcpu-2gb-nyc3-01:~/single-node-kubernetes-cluster# kubectl get deploymentNAME      DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGEnginx     1         1         1            1           11mroot@ubuntu-s-1vcpu-2gb-nyc3-01:~/single-node-kubernetes-cluster# kubectl get podsNAME                     READY     STATUS    RESTARTS   AGEnginx-666865b5dd-w8q9m   1/1       Running   0          11m

Here is service YAML nginx-service.yaml file.

apiVersion: v1kind: Servicemetadata:name: ngnix-servicespec:selector:app: nginxtype: NodePortports:  - protocol: TCPport: 80targetPort: 80

Now, let’s create the service.

kubectl create -f nginx-service.yaml

Top Kubernetes Interview Questions

Question: What is Kubernetes?

Answer: Kubernetes is an open-source container management system originally developed by Google in 2014. This tool holds the responsibilities of container deployment, upscaling and downscaling of containers, and load balancing. It works brilliantly with all the cloud providers. The main purpose is to manage a containerized application in physical, virtual, and cloud environments.

Offering high flexibility, Kubernetes is highly efficient and delivers complex applications consistently that can run in clusters of hundreds to thousands of individual servers. Therefore, it can be said that Kubernetes is not only a container-orchestration system, but a multi-container management solution.

Question: What is a Kubernetes controller manager?

Answer: Kubernetes controller manager is a daemon that is utilized for:

• Namespace creation,

Question: What is container orchestration?

Answer: Container orchestration helps in coordinating the work of all containers to address the requirements of a particular server.

Question: Explain node in Kubernetes.

Answer: It is the smallest unit of the Kubernetes architecture. Through this, a particular machine is defined in a cluster. This can be a virtual machine from a cloud provider or a physical machine in the data center. Moreover, it enables every machine in a cluster to substitute one another.

Question: Explain daemon sets.

Question: What is the use of a namespace in Kubernetes?

Answer:

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What Is The Difference Between Kubernetes And Docker Swarm

Docker Swarm is a default container orchestration tool that comes with Docker. Docker Swarm can only orchestrate simple Docker containers. Kubernetes, on the other hand, helps manage much more complex software application containers. Kubernetes offers support for larger demand production environment.

Whats The Difference Between A Kubernetes Configmap And A Kubernetes Secret

A ConfigMap is a Kubernetes API object used to store data that is not confidential. ConfigMap information is stored in a variety of information formats, such as key-value pairs and JSON. Typically a developer uses a ConfigMap to provide information to the cluster that gets consumed by other API objects.

kind: ConfigMap apiVersion: v1 metadata: name: db-configmap data: # Configuration data as key-value properties database: mongodb database_uri: mongodb://localhost:27017 # Other data in JSON keys: | maximum.connections=5 timeout=10000

A Kubernetes secret is a Kubernetes object that stores information in the cluster in an encrypted format. Typically a secret is used to store confidential information. The example below is a manifest file that describes a Kubernetes secret for a username/password pair. Notice the Base64 encrypted values.

apiVersion: v1kind: Secretmetadata: name: mysecrettype: Opaquedata:  # An encrypted username/password pair username: YWRtaW4= password: MWYyZDFlMmU2N2Rm

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Why Should I Learn Aws

Public cloud service adoption rates are increasing and now is the best time to learn AWS. Following are some of the reasons to learn AWS:

• AWS has over 1 million customers from 190 countries- Amazon
• AWS is as big as its next 4 competitors combined- Business Insider
• An AWS Certified Architect can earn USD $ 125,000- Indeed
• The rate of public cloud services adoption will rise up to 28%- Gartner
• AWS is the fastest-growing public cloud service provider- Forbes

Q5 What Is Container Orchestration

Consider a scenario where you have 5-6 microservices for an application. Now, these microservices are put in individual containers, but wont be able to communicate without container orchestration. So, as orchestration means the amalgamation of all instruments playing together in harmony in music, similarly container orchestration means all the services in individual containers working together to fulfill the needs of a single server.

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Can You Explain About Kubernetes Controller Manager

Different controller processes run on the master nodes which are compiled together to run as a single process which is Kubernetes Controller Manager. Kubernetes controller manager is a daemon that embeds the core control loops shipped with Kubernetes. A control loop is a non-terminating loop that controls the state of the system.

In Kubernetes, a controller is a control loop that sees the shared state of the cluster via an api server and makes changes in an attempt to move the current state towards the desired state.

Controllers that ship with Kubernetes is the – replication controller, namespace controller, endpoints controller, and service accounts controller.

Kubernetes Interview Questions That All Beginners Are Expected To Answer

Question: Explain the Difference between secret and config map.Configmap in Kubernetes is a key-value pair that is used to store data that isnt of any sensitive nature .

Kubernetes secret on the other hand store sensitive data (e.g.

Question: Write the specification for creating a persistent volume.Heres a specification for a persistent volume for visualcv-main:apiVersion: v2.01kind: PersistentVolumemetadata:name: visualcv-mainspec:capacity:storage: 5GivolumeMode: FilesystemaccessModes:

persistentVolumeReclaimPolicy: Retain

Question: How do you check the status of jobs and pods?To check the status of a pod, run this command:kubectl get podsNAME READY STATUS RESTARTS AGEvisualcv-main 1/1 Running 0 59s

To check the status of a job, run this command instead:kubectl get jobNAME DESIRED SUCCESSFUL AGEvisualcv-main 1 0 19s

Question: How do you manage permissions for Kubernetes cluster connections?The permissions for connecting with a Kubernetes cluster is managed by a set of rules that are defined by the Ingress network.

Question: What does Kubernetes Controller Manager do?Kubernetes controller manager is responsible for garbage collection, creation of namespaces, and control loops.

Question: Explain how to perform zero downtime rollout on Kubernetes.To ensure a zero downtime Kubernetes rollout, we use rolling updates strategy. With Rolling Updates strategy, our deployments are pushed incrementally without incurring any downtime on production.

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