Table of contents
- What is Kubernetes and why it is important?
- What is the difference between Docker Swarm and Kubernetes?
- How does Kubernetes handle network communication between containers?
- How does Kubernetes handle the scaling of applications?
- What is a Kubernetes Deployment and how does it differ from a ReplicaSet?
- Explain the concept of rolling updates in Kubernetes.
- How does Kubernetes handle network security and access control?
- How Kubernetes can be used to deploy a highly available application?
- What is a namespace in Kubernetes? Which namespace any pod takes if we don't specify any namespace?
- How does ingress help in Kubernetes?
- Explain different types of services in Kubernetes.
- Explain the concept of self-healing in Kubernetes.
- How does Kubernetes handle storage management for containers?
- How does the NodePort service work?
- What is a multinode cluster and a single-node cluster in Kubernetes?
- Difference between create and apply in Kubernetes?
What is Kubernetes and why it is important?
Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.
One of the best things about using Kubernetes is that the platform helps you drive better business productivity. Since it eliminates the need for most manual processing, you can enhance productivity and drive results. Kubernetes automates many processes, making your business much more efficient.
What is the difference between Docker Swarm and Kubernetes?
The main difference is that Kubernetes is a container orchestration system that manages multiple containers. Docker Swarm does not manage any containers but instead is a cluster manager for Docker containers. Kubernetes also has built-in support for stateful applications, whereas Docker Swarm does not.
How does Kubernetes handle network communication between containers?
In Kubernetes, pods can communicate with each other in a few different ways: Containers in the same Pod can connect to each other using localhost, and then the port number is exposed by the other container. A container in a Pod can connect to another Pod using its IP address.
How does Kubernetes handle the scaling of applications?
The Kubernetes autoscaling mechanism uses two layers: Pod-based scaling supported by the Horizontal Pod Autoscaler (HPA) and the newer Vertical Pod Autoscaler (VPA). Node-based scaling is supported by the Cluster Autoscaler.
What is a Kubernetes Deployment and how does it differ from a ReplicaSet?
Deployments | ReplicaSet |
High-level abstractions that manage replica sets. It provides additional features such as rolling updates, rollbacks, and versioning of the application. | A lower-level abstraction that manages the desired number of replicas of a pod. Additionally, it provides basic scaling and self-healing mechanisms. |
Deployment manages a template of pods and uses replica sets to ensure that the specified number of replicas of the pod is running. | ReplicaSet only manages the desired number of replicas of a pod. |
Deployment provides a mechanism for rolling updates and rollbacks of the application, enabling seamless updates and reducing downtime. | Applications must be manually updated or rolled back. |
It provides versioning of the application, allowing us to manage multiple versions of the same application. It also makes it easy to roll back to a previous version if necessary. | ReplicaSet doesn't provide this feature. |
Explain the concept of rolling updates in Kubernetes.
RollingUpdate implements automated, rolling updates for the Pods in the StatefulSet. RollingUpdate causes the controller to delete and recreate each of its Pod, and each Pod one at a time. It waits until an updated Pod is running and ready before to updating its predecessor.
How does Kubernetes handle network security and access control?
Kubernetes ships an integrated Role-Based Access Control (RBAC) component that matches an incoming user or group to a set of permissions bundled into roles. These permissions combine verbs (get, create, delete) with resources (pods, services, nodes) and can be namespace-scoped or cluster-scoped.
How Kubernetes can be used to deploy a highly available application?
Kubernetes achieves high availability through various components and strategies, including pod replication, node-level redundancy, service discovery and load balancing, and the use of persistent volumes and StatefulSets.
What is a namespace in Kubernetes? Which namespace any pod takes if we don't specify any namespace?
Namespaces are a way to organize clusters into virtual sub-clusters they can be helpful when different teams or projects share a Kubernetes cluster. Any number of namespaces are supported within a cluster, each logically separated from others but with the ability to communicate with each other.
Out of the box, your active namespace is the “default” namespace. Unless you specify a Namespace in the YAML, all Kubernetes commands will use the active Namespace.
How does ingress help in Kubernetes?
The Ingress concept lets you map traffic to different backends based on rules you define via the Kubernetes API. An API object that manages external access to the services in a cluster, typically HTTP. Ingress may provide load balancing, SSL termination and name-based virtual hosting.
Explain different types of services in Kubernetes.
There are several types of services in Kubernetes, each serving a specific purpose:
ClusterIP: This is the default type. It exposes the service on a cluster-internal IP. This means the service is only reachable within the cluster, making it a good choice for communication between different parts of your application.
NodePort: This type exposes the service on a static port on each node's IP. It means the service is accessible on every node's IP address at the specified port. NodePort services are often used for exposing services externally, but they may not be suitable for all production scenarios due to potential port conflicts and security considerations.
LoadBalancer: This type creates an external load balancer in the cloud provider's infrastructure, and assigns a fixed, external IP to the service. LoadBalancer services are useful for distributing incoming network traffic across multiple pods to ensure high availability and redundancy.
ExternalName: This type maps the service to the contents of the externalName field (e.g., a DNS CNAME record). It allows you to use a service name as a DNS alias.
Headless: This type is used when you want to disable the cluster IP and access the pods directly by their IPs or DNS names. It is often used in stateful sets.
Explain the concept of self-healing in Kubernetes.
The idea behind self-healing Kubernetes is simple: If a container fails, Kubernetes automatically redeploys the afflicted container to its desired state to restore operations.
How does Kubernetes handle storage management for containers?
In Kubernetes, the most basic type of storage is non-persistent also known as ephemeral. Each container has ephemeral storage by default this storage uses a temporary directory on the machine that hosts the Kubernetes pod. It is portable, but not durable. Kubernetes supports multiple types of persistent storage.
How does the NodePort service work?
The NodePort service serves as the external entry point for incoming requests for your app. The assigned NodePort is publicly exposed in the kubeproxy settings of each worker node in the cluster. Every worker node starts listening on the assigned NodePort for incoming requests for the service.
What is a multinode cluster and a single-node cluster in Kubernetes?
Single-Node Cluster: A single-node cluster, also known as a "Minikube" cluster, is a lightweight Kubernetes cluster that consists of only one node. It's often used for local development and testing purposes. Minikube allows developers to run a simplified Kubernetes environment on their local machine, providing a way to experiment with Kubernetes concepts and deploy applications without the complexity of a full production cluster.
Multi-Node Cluster: A multi-node cluster is a production-level Kubernetes environment consisting of multiple nodes. Each node in the cluster plays a specific role, such as a control plane node or a worker node. The control plane manages and orchestrates the cluster, while the worker nodes run the actual containers. Multi-node clusters are designed for scaling, high availability, and workload distribution. They are the backbone of running applications in production using Kubernetes.
Difference between create and apply in Kubernetes?
Create: The kubectl create command is used to create new resources in the cluster. When you use create, you provide the resource configuration directly on the command line or from a configuration file. If the resource already exists, attempting to create it again will result in an error.
Apply: The kubectl apply command is used to create or update resources based on a configuration file. It applies changes to the cluster based on the differences between the current state and the desired state defined in the configuration file. If a resource doesn't exist, apply creates it, and if it does exist, apply updates it. This is a powerful feature for maintaining desired configurations in a declarative way.