WHAT IS KUBERNETES

Question 1

What is Kubernetes?

Answer 1

Kubernetes is an open-source container orchestrator that manages container-based applications based on the requirements of the administrator or developer.

Question 2

List the key functionalities Kubernetes offers for managed containerised apps

Answer 2

●Deployment:
●Scaling
●Workload Placement
●Infrastructure Abstraction
●Desired State Management

Question 3

Kubernetes offers several key functionalities for managing containerized applications:

What does Kubernetes manage in terms of deployment?

Answer 3

Kubernetes manages the deployment of pods, determining how and where they are deployed within the cluster.

Question 4

Kubernetes offers several key functionalities for managing containerized applications:

How does Kubernetes handle scaling?

Answer 4

Kubernetes can automatically scale applications by adding or removing pod replicas based on resource utilization or other metrics. This allows applications to handle varying workloads and maintain performance.

Question 5

Kubernetes offers several key functionalities for managing containerized applications:

What is workload placement in Kubernetes?

Answer 5

Kubernetes determines which nodes pods should be deployed to based on factors like resource requirements and co-residency constraints.

Question 6

Kubernetes offers several key functionalities for managing containerized applications:

What are infrastructure abstractions in Kubernetes?

Answer 6

Kubernetes provides abstractions for underlying infrastructure, simplifying the management of storage, networking, and workload placement

Question 7

Kubernetes offers several key functionalities for managing containerized applications:

What is desired state management in Kubernetes?

Answer 7

Kubernetes ensures the system’s actual state matches the desired state defined in code. Controllers constantly monitor the system and take corrective actions to maintain the desired configuration.

Question 8

List the benefits Kubernetes offers for managing containerised applications:

Answer 8

●Speed of Deployment
●Adaptability and Resilience:
●Load Balancing
●Infrastructure Complexity Hiding
●Horizontal Scaling
●High Availability

Question 9

What benefit does Kubernetes provide for the deployment of containerized applications?

Answer 9

Speed of Deployment: Kubernetes enables rapid deployment of containerized applications.

Question 10

What benefit does Kubernetes provide towards adaptability and resilience?

Answer 10

Kubernetes allows for quick absorption of changes and auto-healing by replacing failed pods, ensuring applications can recover quickly from failures

Question 11

How is load balancing a benefit in Kubernetes?

Answer 11

Kubernetes provides load-balancing capabilities to distribute incoming traffic efficiently across application instances, enhancing performance and availability.

Question 12

How is Infrastructure Complexity Hiding a benefit in Kubernetes?

Answer 12

Kubernetes simplifies the management of complex infrastructure by handling storage, network configuration, and workload placement.

Question 13

How is horizontal scaling a benefit for Kubernetes?

Answer 13

Kubernetes supports both manual and automatic horizontal scaling, enabling applications to adapt to changing demands by adding or removing worker nodes.

Question 14

How is Infrastructure Complexity Hiding a benefit in Kubernetes?

Answer 14

Kubernetes ensures high availability by replicating pods to multiple cluster nodes, eliminating downtime due to pod or node failures.

Question 15

What does the Kubernetes API provide and what are API objects?

Answer 15

The Kubernetes API provides a collection of objects that can be used to build and define systems for deployment in code.

These objects, known as API objects, represent the system’s state and allow the configuration of this state both declaratively and imperatively

Question 16

What is the difference between declarative and imperative configuration?

Answer 16

Declarative configuration means describing the desired deployment, while imperative configuration involves executing a sequence of commands to achieve the desired state

Question 17

The Kubernetes API is implemented and available via the API Server

What is the role of the Kubernetes API Server?

Answer 17

The API Server is the central hub for information in a Kubernetes cluster.

It is the sole way users can interact with clusters, and it’s also how Kubernetes interacts with the cluster.

The API Server is a RESTful API over HTTP/S using JSON2. When the API server receives commands, that information is serialized and persisted into a cluster data store.

Administrators and developers interact with Kubernetes through the API Server to deploy and manage workloads. The API Server is also where Kubernetes cluster components interact to understand the system’s current state and make changes as needed to ensure the desired state.

Question 18

List examples of the Kubernetes API objects.

Answer 18

●Pods
●Controllers
●Services
●Storage
●Namespaces
●ConfigMaps
●Secrets

Question 19

What are pods?

Answer 19

Pods are the most basic unit of work in Kubernetes, consisting of one or more application containers deployed on one or more cluster nodes. They can be configured with resource requirements.

Kubernetes directly manages pods, not containers.

Question 20

What does it mean that pods are ephemeral in Kubernetes?

Answer 20

Pods are ephemeral, meaning they are not designed to be redeployed. If a pod fails, the controller will delete it and deploy a new one.

Question 21

What does it mean that pods are atomic in Kubernetes?

Answer 21

Pods are atomic, meaning they either exist or don’t. If one container in a multi-container pod fails, the entire pod becomes unavailable.

Question 22

What unique network characteristic does each pod have?

Answer 22

Each pod receives a unique internal IP address, which is also ephemeral

Question 23

What happens to pods if the cluster goes down and then comes back up?

Answer 23

If a pod is running and the cluster goes down, the pod will be automatically restarted when the cluster comes back up.

Question 24

How does Kubernetes ensure the state and health of pods?

Answer 24

Kubernetes uses probes to constantly track the state and health of pods. Controllers respond to pod state and health, taking actions to maintain the desired state, such as deploying new pods if needed.

Question 25

What are Kubernetes Controllers?

Answer 25

Controllers are Kubernetes objects that ensure the actual state of the cluster matches the desired state defined in code. They constantly monitor the system and take actions to maintain the desired configuration.

Question 26

What do Controllers do with pods?

Answer 26

Controllers create and manage pods. If a pod fails, a controller will delete the failed pod and deploy a new one. They use probes to check if pods are up and running and if the applications within those pods are healthy.

Question 27

What is the purpose of a ReplicaSet Controller in Kubernetes, and how is it typically used in deployments?

Answer 27

A ReplicaSet Controller ensures a specified number of replicas of a pod are running at all times. If a pod fails, the ReplicaSet deploys another pod to maintain the desired number of replicas. ReplicaSets are often defined within a deployment rather than being deployed directly.

Question 28

What is the purpose of StatefulSets in Kubernetes, and for what type of applications are they most useful?

Answer 28

StatefulSets are controllers for stateful applications that require persistent storage. They are most useful for back-end databases and applications where maintaining state, such as transaction history or shopping cart data, is important.

Question 29

What unique feature of StatefulSets ensures data persistence even if a pod fails?

Answer 29

Each pod in a StatefulSet is assigned a unique and reusable identity and gets its own persistent volume, which retains data even if the pod is restarted or rescheduled.

Question 30

How are pods in a StatefulSet deployed and terminated, and why is this order important?

Answer 30

Pods in a StatefulSet are deployed in sequential order and terminated in reverse order. This is crucial for applications where dependencies exist between pods.

Question 31

What mechanisms do StatefulSets provide to ensure continuous operation and data consistency during updates?

Answer 31

StatefulSets automatically replace failed pods and support rolling updates, allowing gradual updates without downtime. They ensure data consistency through synchronization between replicas or using centralized storage.

Question 32

How do StatefulSets ensure data integrity in stateful applications with multiple replicas?

Answer 32

Data integrity is maintained through synchronization between replicas or by using a centralized data store. For example, one pod may be designated as the primary replica for handling reads and writes, while others synchronize their data with it.

Question 33

What field in a StatefulSet's YAML configuration is used to match and manage its pods?

Answer 33

The spec.selector field in the YAML configuration is used to match pod labels, allowing the StatefulSet to identify and manage its pods.

Question 34

What is the role of deployment controllers in Kubernetes?

Answer 34

Deployment controllers manage the state and rollout of ReplicaSets. They are a higher-level abstraction than ReplicaSets, offering additional features for managing deployments.

Question 35

How do deployment controllers simplify managing the desired state of an application?

Answer 35

Deployment controllers define both the pods and the ReplicaSets needed for a deployment, allowing everything to be managed in one place.

Question 36

What Kubernetes commands can you use to view deployments and ReplicaSets?

Answer 36

To view deployments: kubectl get deployment To view ReplicaSets: kubectl get replicaset

Question 37

What are the two scaling options provided by deployment controllers in Kubernetes?

Answer 37

Manual scaling: Use the command kubectl scale --replicas= to set the desired number of replicas. Automatic scaling: Use a Horizontal Pod Autoscaler (HPA), defined with a command like kubectl autoscale deployment/nginx-deployment --min=10 --max=15 --cpu-percent=90%. An HPA automatically scales the number of pod replicas up or down based on observed metrics, such as CPU utilization.

Question 38

What are the main differences between Deployments and Stateful sets?

Answer 38

Deployment: - Pods use the same storage volumes - Pods are assigned a random identity - It is useful for front-end web apps (we don’t have to worry about retaining state) StatefulSet: - each pod uses its own persistent volume - Pod gets a unique reusable identity - it is useful for back-end databases

Question 39

What is the primary purpose of services in Kubernetes?

Answer 39

Services provide a persistent access point to applications running in pods, abstracting away the ephemeral nature of pods.

Question 40

How do Kubernetes services ensure persistency for applications?

Answer 40

Kubernetes persistently assigns an IP address and DNS name to services, allowing users to access the application without knowing specific pod details.

Question 41

What role do services play in networking within Kubernetes?

Answer 41

Services act as a networking abstraction, providing a stable entry point to pod applications.

Question 42

How do Kubernetes services enhance application scalability and availability?

Answer 42

Services distribute traffic across multiple pods, enabling load balancing and improving scalability and availability.

Question 43

How do services adapt to changes in the pod lifecycle?

Answer 43

Services are dynamically updated by Kubernetes to reflect changes in the pod lifecycle, such as adding or removing pods, ensuring the service remains functional.

Question 44

How can services in Kubernetes contribute to application scalability?

Answer 44

Services can be scaled by adding or removing pods, making it easy to adjust application capacity as needed.