All the definitions you need to know for Kubernetes Interview

1. Kubernetes cluster is a set of physical or virtual hardware, which essentially constitute a set of hosts or servers or computers.



2. A node is a master node or worker node, It runs a set of services. Every cluster needs at least one master and at least one worker node. The worker nodes can be thought of as a computer where the business enterprise runs and application or applications for business purposes. A node in Kubernetes is either physical or virtual hardware that manages pods and a container runtime.


3. Kube- aipserver- component of master node that manages administrating of cluster through command line/API interface.


4. Kube scheduler (Component of master node)- distributes the processing two containers.


5. Cube control manager-this is also the part of master node and checks for the failure of node container and pods.


6. Kubectl- The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs.


7.Kops- tool used to install a Kubernetes cluster on aws.


https://asciinema.org/a/97298


8. AKS –( Azure Kubernetes Services) allows you to quickly deploy a production ready Kubernetes cluster in Azure.


9. Node Controller- component of master node that manages nodes.


10. Kubelet- service that communicates between master and containers. Maintains a set of power attributes. Containers are not the kubernetis object so those are run by Kubelet hence Kubelet runs at pod level.


11. Minikube- configuration to install Kube on local machine.


12. Kubectl proxy- The kube-proxy runs on each nodes for the network level,

it distributes the network information.

The kubecti proxy allows the dashboard to be run with the server and port 127.0.0.1:8001.

https://localhost:8001/healthz -this will give the status of cluster.


13. Deployment to Kuberetes-


14. Scaling, update and rollback a deployment-

A Deployment provides declarative updates for Pods and ReplicaSets. Read the following article for more about deployments:

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/


For different methods on scaling deployments, use this link:

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#scaling-a-deployment


To update a deployment, follow the steps in the following article:

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#updating-a-deployment


Sometimes, you may want to rollback a Deployment; for example, when the Deployment is not stable, such as crash looping. By default, all of the Deployment’s rollout history is kept in the system so that you can rollback anytime you want. For more on rolling back deployments, take a few minutes to explore the following article:

https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#rolling-back-a-deployment


15. Kubernetes administrator -

The Kubernetes administrator role covers node installation and configuration.



16. ReplicaSets are replicated pods. So replicaSets or replicas run as pods. ReplicaSets supports scaling up pods to ensure a multi-image solution is running for performance and redundancy. So replicaSets can be applications that are scaled up. ReplicaSets have different attributes one of which is the desired state where the number of desired or or replicas running. So it's the number of replicas that essentially we say have to be running. If the number of replicas running drops below the desired number, Kubernetes creates new replicas to reach the desired number of replicas running with the desired state.


17.DaemonSet is a process that makes certain a pod is running on the eligible nodes. DaemonSets are similar to deployments in that they both create pods and those pods are expected to continuously run.


18. A stateful set is an API object that runs the workload of stateful applications. Stateful application is ones that require network IDs, persistent storage, scaling, rolling updates.


19. Etcd- storage for cluster management.


20. PV and PVCs ( Persistent Volumes and PersistentVolumeClaims) – Storage for Kubernets-

read the following document that describes the current state of persistent volumes in Kubernetes:

https://kubernetes.io/docs/concepts/storage/persistent-volumes/



21. CSI ( container storage interface) -it's a standard developed to solve problems related to adding new storage.

For more information about CSI for Kubernetes GA, read the following article

https://kubernetes.io/blog/2019/01/15/container-storage-interface-ga/



to know the basics of Kubernets' componets-

https://www.mltutor.com/post/kubernetes-introduction-and-components





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