Preparing For A Kubernetes Job Interview? We've Got You

Prepare for a job interview with AWS Kubernetes? don’t worry! This article will provide an interview guide covering common Kubernetes interview questions you may encounter.

Summary of key points

• Kubernetes is an open source container orchestration platform that is critical to DevOps because it automates the deployment, scaling, and management of containerized applications, thereby speeding up software development and delivery.
• Kubernetes can be deployed on AWS using Amazon Elastic Kubernetes Service (EKS), which integrates with other AWS services to provide a seamless experience in deploying and managing containerized applications.
• Kubernetes architecture key components include nodes, control planes, pods, services, and Ingress. Kubernetes namespaces help divide cluster resources among multiple users or teams, prevent naming conflicts and facilitate resource sharing.
• Kubernetes ensures high availability and scalability with features such as horizontal Pod Autoscaler (HPA) and cluster Autoscaler. It also uses persistent volumes (PV) and persistent volume declarations (PVC) to handle persistent storage, thereby abstracting the underlying storage infrastructure.

1. What is Kubernetes and why is it so important to DevOps?

Kubernetes is an open source container orchestration platform that automates the deployment, scaling and management of containerized applications. It is crucial for DevOps because it helps simplify the deployment and management process of applications, thereby speeding up software development and delivery.

2. How does Kubernetes work with AWS?

Kubernetes can be deployed on AWS using Amazon Elastic Kubernetes Service (EKS), a managed service that allows you to easily run Kubernetes on AWS without installing and operating the Kubernetes control plane. EKS integrates with other AWS services such as Elastic Load Balancing, Amazon RDS, and AWS Identity and Access Management (IAM) to provide a seamless experience for deploying and managing containerized applications.

3. What are the key components of the Kubernetes architecture?

Key components of the Kubernetes architecture include:

• Node: The physical or virtual machine running the containerized application.
• Control Plane: A set of components that manage the overall state of the cluster, including API server, etcd, controller manager, and scheduler.
• Pod: The smallest and simplest unit in the Kubernetes object model, representing a single instance of a running process in the cluster.
• Service: A way to expose applications running on a set of pods as network services.
• Ingress: A API object that manages external access to services in a cluster, usually over HTTP.

4. What is the role of Kubernetes master node?

The Kubernetes master node (also known as the control plane) is responsible for managing the overall state of the cluster. It includes API servers (exposing Kubernetes APIs); etcd (storing configuration data); controller manager (running the controller to regulate the state of the cluster); and scheduler (assigning the pod to the node).

5. What is a Kubernetes namespace and what is its use?

Kubernetes namespace is a way to divide cluster resources between multiple users or teams. It provides a scope for resource names that allow you to organize and isolate resources based on the purpose or ownership of the resource. Namespaces are useful for managing large clusters with many users, as they help prevent naming conflicts and facilitate resource sharing and access control.

6. How to deploy applications on Kubernetes?

To deploy an application on Kubernetes, you need to create a set of configuration files that define the required state of the application, including container images, replicas, and network settings. These files are usually written in YAML format and include:

• Deployment: Describes the required status of the application, including container images, replicas, and update policies.
• Service: Expose the application to the network, whether within or outside the cluster.
• Ingress (optional): Manage external access to services in the cluster, usually via HTTP.

After creating the configuration files, you can use the kubectl command line tool to apply them to your cluster.

7. What is Kubernetes ConfigMap and how is it used?

Kubernetes ConfigMap is an API object that allows you to store non-confidential configuration data in the form of key-value pairs. It can be used to separate configuration data from container images, making it easier to update and manage application configurations without rebuilding images. Pods can use ConfigMap as an environment variable, command line parameter, or as a file installed on a volume.

8. What is Kubernetes Secret, and what is the difference between it and ConfigMap?

Kubernetes Secret is an API object that allows you to store sensitive data such as passwords, tokens, or keys in a more secure way than using ConfigMap. Secrets are encrypted at rest and only authorized pods can access them. Like ConfigMap, Secret can be used by Pods as environment variables, command line parameters, or as files installed in volumes. The main difference between Secret and ConfigMap is the level of security provided when storing sensitive data.

9. How to scale applications in Kubernetes?

In Kubernetes, you can extend your application by adjusting the number of replicas specified in the Deployment configuration. You can manually update the number of replicas, or use the horizontal Pod Autoscaler (HPA) to automatically scale the number of pods based on CPU utilization or custom metrics. Additionally, you can use the cluster autoscaler to automatically adjust the size of the underlying node pool according to the application's resource requirements.

10. What are the best practices for Kubernetes security?

Some best practices for Kubernetes security include:

• Use role-based access control (RBAC) and limit network access to the control plane to limit access to the Kubernetes API.
• Protect container images using trusted base images, scan vulnerabilities, and signature images.
• Use network policies to control traffic between pods and isolate sensitive workloads.
• Encrypt the Secrets at rest and in transit and use Kubernetes native Secret management solutions such as AWS Secrets Manager or HashiCorp's Vault to protect sensitive information.

11. What is the difference between a Kubernetes cluster and a node?

A Kubernetes cluster consists of one or more nodes, each node running one or more containers. A node is the underlying physical or virtual machine that runs these containers and provides the necessary resources (such as CPU and memory) for their operations.

12. Can you explain how Kubernetes handles network communication between pods?

To enable communication between pods running in a Kubernetes cluster, Kubernetes implements a so-called Pod network. This network typically uses an overlay network based on technologies such as VXLAN or IP-in-IP tunneling, allowing Pods running on different nodes to communicate with each other as if they were on the same physical host.

13. How does Kubernetes' scaling mechanism work?

Extensions can be achieved by changing the number of replicas required for any given deployment, replica set, stateful set, daemon, job, etc. After applying this configuration change, the controller responsible for managing the resource ensures that a new instance is created (or terminated an existing instance) until the desired state is reached.

14. How to ensure high availability of AWS EKS clusters?

The best way to ensure high availability of Amazon EKS clusters is to spread it in multiple Availability Zones within one region. By deploying applications across Availability Zones, you can increase their resilience to failures and enable self-healing with activity probing. Horizontal auto-scaling and scrolling updates can also work.

Other approaches may include reducing downtime during deployment by implementing blue-green deployments of services such as Nginx, ingress controllers, possible use of canary releases (allowing security testing and tuning), and from disaster recovery Steps backup and recovery solutions, such as AWS EBS for data persistence and disaster recovery.

15. How does Kubernetes handle persistent storage?

Kubernetes uses persistent volumes (PV) and persistent volume declarations (PVC) to abstract the underlying storage infrastructure. PV represents a physical storage block in the cluster, while PVC represents a request for this particular type of resource. When a Pod needs access to some persistent storage, it is referenced through the PVC definition and then bound to the available PV by the PV controller. The PV is installed on the required nodes of the Pod defined by Kubernetes, and any related features will be managed according to your corresponding settings, including the backup/restore process at the Pod level or node level according to your preferences.

Conclusion

The above are the answers to fifteen potential interview questions about Kubernetes. Hope these answers help you get your next job!

Kubernetes FAQ (FAQ)

What is the role of Kube-proxy in Kubernetes?

Kube-proxy is a key component of Kubernetes. It runs on each node to handle a single host subnet and ensure that the service is available to external users. It is responsible for maintaining network rules on nodes. These network rules allow network communication to your Pod from network sessions inside or outside the cluster.

How does Kubernetes handle failover?

Kubernetes has built-in failover handling mechanism. When a node fails, the replica controller notices the service drop and restarts the pod on different nodes. This ensures that the number of pods required to run at all times, providing high availability.

What is the difference between ReplicaSet and Replication Controller in Kubernetes?

ReplicaSet and Replication Controller in Kubernetes are both designed to maintain stable replica pod sets running at any given time. However, ReplicaSet is a newer resource that supports collection-based selector requirements, while Replication Controller only supports equality-based selector requirements.

How does Kubernetes provide scalability?

Kubernetes provides scalability through features such as its horizontal Pod Autoscaler (HPA) and cluster Autoscaler. HPA scales the number of Pod replicas based on observed CPU utilization, while the cluster autoscaler scales the cluster size according to requirements.

What is the role of Ingress Controller in Kubernetes?

The Ingress Controller in Kubernetes is responsible for implementing Ingress rules. It is usually a load balancer and can also have other features such as SSL termination, path rewriting, or name-based virtual hosts.

How does Kubernetes ensure data persistence?

Kubernetes ensures data persistence through persistent volumes (PV) and persistent volume declarations (PVC). A PV is a piece of storage space in the cluster, while a PVC is a user's request for storage space. They decouple the storage configuration from the Pod to ensure data persistence when the Pod is restarted.

What is the role of Service in Kubernetes?

The Service in Kubernetes is an abstraction that defines a set of logical pods and policies to access them. Services enable loose coupling between dependent Pods, providing discovery and load balancing capabilities.

How does Kubernetes handle updates and rollbacks?

Kubernetes uses rolling updates and rollbacks to manage updates. Rolling updates gradually replace old pods with new pods to ensure zero downtime. If there is a problem, Kubernetes provides a rollback feature to restore to its previous state.

What is the difference between Pod and Deployment in Kubernetes?

Pod is the smallest and easiest unit in the Kubernetes object model that you can create or deploy. Deployment, on the other hand, is a higher level concept that manages Pods and ReplicaSets. It provides declarative updates to Pods and ReplicaSets.

How does Kubernetes provide service discovery and load balancing?

Kubernetes provides service discovery and load balancing through services and Ingress. The service provides internal load balancing and discovery using stable IP addresses and DNS names. Ingress provides HTTP and HTTPS routing to the service, with external load balancing, SSL termination, and name-based virtual hosting capabilities.

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