Ace Your Kubernetes Interview-I

Day 37 Task: Top 16 Kubernetes Interview Questions and Answers Part-I

Hello everyone I am back with another task of DevOps😊.

This is Part 01 Interview questions of Kubernetes.

Note: All answers are in descriptive manner if you want short answers then the PDF of short answers is given in Part 03

So let’s Start…

01. What is Kubernetes and why it is important?

Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. It provides a container-centric management environment and helps to abstract away the underlying infrastructure, enabling developers to focus on writing applications rather than managing infrastructure.

Kubernetes is important for several reasons.

First, it simplifies the deployment and management of containerized applications, making it easier for developers to build and deploy applications quickly and reliably.

Second, it provides a flexible and scalable platform that can run on-premises, in the cloud, or in hybrid environments.

Third, it helps to improve application availability and resilience by automatically scaling and distributing workloads across nodes in a cluster.

Fourth, it supports a wide range of container runtimes, making it easy to work with different types of containers.

Finally, it has a large and active community of users and contributors, which ensures that the platform is constantly evolving and improving.

Example:

Consider a scenario where a company has multiple applications running in different environments such as development, testing, and production. Kubernetes allows the company to manage these applications across all environments in a consistent and streamlined manner.

Developers can deploy their applications using a standardized process, and operations teams can manage and monitor the applications across all environments using a single dashboard. This helps organizations achieve faster time to market, improve scalability, and reduce operational overhead.

02. What is difference between Docker-swarm and Kubernetes?

Docker Swarm and Kubernetes are both container orchestration platforms, but there are some differences between them:

1. Architecture: Docker Swarm follows a simpler architecture with a single manager node and multiple worker nodes. On the other hand, Kubernetes follows a more complex architecture with a master node and multiple worker nodes.
2. Scaling: Docker Swarm provides scaling of services and replicas, but it lacks the advanced scaling capabilities of Kubernetes, such as auto-scaling and horizontal pod autoscaling.
3. Networking: Docker Swarm provides a simple overlay network, whereas Kubernetes provides a more advanced networking model, including support for multiple network plugins.
4. Stateful applications: Kubernetes provides better support for stateful applications than Docker Swarm.
5. Ecosystem: Kubernetes has a more extensive ecosystem with a larger community, more third-party integrations, and support for multiple cloud providers.

Example:

Suppose you have a containerized application that needs to be deployed and managed across multiple nodes. If you choose Docker Swarm, you can easily set up a cluster with a single manager node and multiple worker nodes. You can then deploy your application and scale it horizontally by adding more worker nodes to the cluster.

If you choose Kubernetes, you will need to set up a more complex architecture with a master node and multiple worker nodes. You will also need to configure additional features like load balancing, service discovery, and storage management. However, Kubernetes offers more advanced features like auto-scaling, rolling updates, and self-healing, which can be useful for larger and more complex applications.

03. How does Kubernetes handle network communication between containers?

Kubernetes provides a built-in networking model to enable communication between containers running on different nodes in a cluster. This is achieved through the implementation of a flat network model, where each pod is assigned a unique IP address that can be used by the containers within the pod to communicate with each other.

Kubernetes provides two types of networking:

1. Pod-to-Pod Networking: Each pod is assigned a unique IP address that is used by the containers within the pod to communicate with each other. Pods can communicate with other pods using their IP addresses and ports.
2. Service Networking: Kubernetes provides a virtual IP address for each service, which is used to load balance traffic between pods. Services can be exposed to the outside world using a Kubernetes Ingress resource or by creating a NodePort or LoadBalancer service.

Example:

Let’s say you have a microservices application running in Kubernetes, with each microservice running in a separate container within a pod. Each microservice is listening on a specific port, and you want to allow traffic to flow between them. You can create a Kubernetes service for each microservice, which will expose the microservice to the other containers in the pod and to the outside world.

The service will automatically load balance traffic to the different replicas of the microservice and handle service discovery using DNS. You can also use network policies to restrict traffic between microservices to only the necessary ports and protocols, improving security and reducing the attack surface.

04. How does Kubernetes handle scaling of applications?

Kubernetes has a built-in autoscaling feature that can automatically adjust the number of replicas of an application based on the demand for resources. This feature is controlled by the Horizontal Pod Autoscaler (HPA) resource in Kubernetes.

When an HPA is created, it specifies the target CPU utilization or custom metric for the application. Kubernetes monitors the application and automatically adjusts the number of replicas to maintain the desired utilization or metric value. When the demand for resources increases, Kubernetes can scale up the application by creating new replicas. When the demand decreases, Kubernetes can scale down the application by deleting excess replicas.

Example:

suppose an application is running in a Kubernetes cluster with a defined HPA that targets a CPU utilization of 50%. If the CPU utilization of the application exceeds 50%, Kubernetes can automatically scale up the application by creating new replicas. If the CPU utilization falls below 50%, Kubernetes can scale down the application by deleting excess replicas. This ensures that the application is always running with the optimal number of replicas to handle the current demand for resources.

05. What is a Kubernetes Deployment and how does it differ from a ReplicaSet?

A Kubernetes Deployment is a higher-level resource that provides declarative updates to the desired state of the ReplicaSets and Pods it manages. It provides a way to describe how many replicas of a Pod should be running and handles creating, updating, and deleting Pods as necessary to achieve the desired state. Deployments allow you to roll out changes to your application in a controlled manner and to rollback to a previous state if needed.

A ReplicaSet, on the other hand, is a lower-level resource that ensures a specified number of replicas of a Pod are running at any given time. It creates and maintains a set of identical Pods, and will automatically replace any Pods that fail or are terminated. ReplicaSets provide the basic scaling mechanism for Kubernetes, and Deployments use ReplicaSets to manage the state of the application.

Example:

let’s say you have a Deployment that specifies you want three replicas of your application running. The Deployment will create a ReplicaSet with three replicas and monitor the state of the Pods. If a Pod fails or is terminated, the ReplicaSet will automatically create a new Pod to replace it. If you need to update your application, you can update the Deployment to create a new ReplicaSet with the updated configuration, and the Deployment will manage the rolling update of the Pods to the new ReplicaSet.

Click Here for Part 02 Interview questions of Kubernetes.

Click Here for Part 03 Interview questions of Kubernetes.

🔶That’s all about today’s task of DevOps journey.

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