1.What is Kubernetes and why it is important?
Kubernetes also known as K8s or kube is an open source container orchestration platform that automates many of the manual processes involved in deploying, managing, and scaling containerized applications. It is important because it simplifies and streamlines the management of containerized applications, ensures high availability and provides efficient resource utilization.
It also provides other benefits such as self-healing of pods, scalability, resource optimization, rolling updates, declarative configuration, networking and service discovery and security and access control.
2.What is difference between docker swarm and kubernetes?
Docker Swarm and Kubernetes are both container orchestration platforms, but they have some key differences.
Docker Swarm is a native Docker container orchestration platform. It is easier to set up and use than Kubernetes, but it is not as feature-rich or scalable.
Kubernetes is a more powerful and feature-rich container orchestration platform.
It is more scalable than Docker Swarm and offers a wider range of features, such as self-healing, rolling updates, and service discovery.
3. How does Kubernetes handle network communication between containers?
Kubernetes uses a network plugin to handle network communication between containers. The default network plugin is Kubenet, which creates a virtual network for each pod.
Kubernetes also supports other network plugins, such as Flannel and Calico. These plugins provide more advanced networking features, such as support for multiple IP addresses per pod and routing between pods on different nodes.
4. How does Kubernetes handle scaling of applications?
Kubernetes can scale applications up or down by changing the number of replicas of a deployment. Replicas are identical copies of a pod, and Kubernetes will ensure that there is always the desired number of replicas running.
Kubernetes can also automatically scale applications based on metrics, such as CPU usage or memory usage. This is called horizontal pod autoscaling (HPA).
5.What is a Kubernetes Deployment and how does it differ from a ReplicaSet?
A Kubernetes Deployment is a higher-level abstraction than a ReplicaSet. It provides a declarative way to specify the desired state of an application, and Kubernetes will automatically work to achieve that state.
A ReplicaSet is a lower-level abstraction that simply ensures that a specified number of replicas of a pod are always running.
Deployments offer a number of advantages over ReplicaSets, including:
Rolling updates: Deployments can perform rolling updates, which means that they can gradually update an application without any downtime.
Self-healing: Deployments can self-heal, meaning that they can automatically restart failed pods.
Rollbacks: Deployments can be rolled back to a previous version if there is a problem with a new deployment.
6. Can you explain the concept of rolling updates in Kubernetes?
A rolling update is a type of deployment that updates an application gradually without any downtime.
To perform a rolling update, Kubernetes creates a new deployment with the desired updates. Kubernetes then gradually updates the pods in the old deployment to the new deployment.
Once all of the pods in the old deployment have been updated, Kubernetes deletes the old deployment.
Rolling updates are a safe and reliable way to update applications in Kubernetes.
7. How does Kubernetes handle network security and access control?
Kubernetes uses a number of features to handle network security and access control, including:
Network policies: Network policies can be used to control the traffic that flows between pods and the outside world.
Pod security policies: Pod security policies can be used to control the security settings of pods.
Service accounts: Service accounts can be used to grant pods access to Kubernetes resources.
Role-based access control (RBAC): RBAC can be used to control which users have access to Kubernetes resources and what they can do with those resources.
8. Can you give an example of how Kubernetes can be used to deploy a highly available application?
To deploy a highly available application in Kubernetes, you can use a deployment with multiple replicas and a load balancer. You can also use a number of other features to improve the availability of your application, such as:
Health probes: Health probes can be used to check the health of pods and restart them if they fail.
Affinity and anti-affinity rules: Affinity and anti-affinity rules can be used to control how pods are scheduled across nodes. This can help to ensure that your pods are distributed evenly across the cluster and that no single node is overloaded.
Node drain: Node drain can be used to safely remove nodes from the cluster without impacting your applications. This is useful for performing maintenance on nodes or for scaling down your cluster.
Here is a more specific example of how to deploy a highly available web application in Kubernetes:
Create a deployment with multiple replicas of your web application pod.
Create a service for your deployment.
Create a load balancer for your service.
Configure the load balancer to distribute traffic to the pods in your deployment.
Configure health probes to check the health of your pods and restart them if they fail.
Configure affinity and anti-affinity rules to control how your pods are scheduled across nodes.
9. What is namespace is kubernetes? Which namespace any pod takes if we don't specify any namespace?
A namespace is a logical isolation mechanism in Kubernetes. It allows you to group related resources together and separate them from other resources in the cluster.
If you do not specify a namespace when creating a pod, the pod will be created in the default namespace.
10. How ingress helps in kubernetes?
Ingress is a Kubernetes feature that provides a way to route traffic from outside the cluster to services inside the cluster.
Ingress can be used to:
Terminate TLS connections: Ingress can be used to terminate TLS connections before they reach the pods in the cluster. This can help to improve the security and performance of your applications.
Route traffic to different services: Ingress can be used to route traffic to different services in the cluster based on the path of the incoming request. This allows you to have multiple services running on the same port, and Ingress will route traffic to the correct service based on the path.
Load balance traffic across multiple services: Ingress can be used to load balance traffic across multiple instances of a service. This can help to improve the performance and scalability of your applications.
11.Explain different types of services in kubernetes?
There are four types of services in Kubernetes:
ClusterIP: ClusterIP services are the default type of service. They expose pods within the cluster to other pods in the cluster.
NodePort: NodePort services expose pods on a specific port of each node in the cluster. This allows traffic to reach the pods from outside the cluster.
LoadBalancer: LoadBalancer services expose pods to external traffic using a cloud provider load balancer.
ExternalName: ExternalName services provide a way to create a DNS record that maps to an external name. This allows pods within the cluster to access external services by name, without needing to know the IP address.
12.Can you explain the concept of self-healing in Kubernetes and give examples of how it works?
Self-healing is a key feature of Kubernetes that allows it to automatically detect and recover from failures in the cluster.
Kubernetes uses a number of different mechanisms to achieve self-healing, including:
Restarting failed pods: Kubernetes will automatically restart failed pods.
Rescheduling pods: Kubernetes will reschedule pods to nodes that are healthy and have the resources to run the pod.
Scaling up deployments: Kubernetes can automatically scale up deployments to compensate for failed pods.
13. How does Kubernetes handle storage management for containers?
Kubernetes offers various storage options, including Persistent Volumes (PV) and Persistent Volume Claims (PVC) to provide storage for containers. Storage classes and volume plugins are used to manage storage resources.
14. How does the NodePort service work?
NodePort services expose pods on a specific port of each node in the cluster. This allows traffic to reach the pods from outside the cluster.
To access a NodePort service from outside the cluster, you need to know the IP address of a node in the cluster and the port number of the service.
For example, if you have a NodePort service running on port 3000, you can access it at http://<node-ip-address>:3000 from outside the cluster.
15.What is a multinode cluster and single-node cluster in Kubernetes?
A multinode cluster is a Kubernetes cluster that has multiple nodes. This type of cluster is typically used for production deployments, as it provides high availability and scalability.
A single-node cluster is a Kubernetes cluster that has only one node. This type of cluster is typically used for development or testing purposes, as it is easier to set up and manage than a multinode cluster.
16.Difference between create and apply in kubernetes?
The create command creates a new Kubernetes resource. The apply command creates a new Kubernetes resource or updates an existing Kubernetes resource to match the desired state specified in the Kubernetes configuration file.
If the resource does not exist, the apply command will create it. If the resource already exists, the apply command will update it to match the desired state specified in the Kubernetes configuration file.
The apply command is typically used when you are deploying a Kubernetes application. It is a safer way to deploy applications than the create command, as it will not overwrite any existing resources.
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