What Is Kubernetes and Why It Is Used? A Complete Guide

The Kubernetes is basically an open-source, portable, extensible container orchestration engine which is being used for automating deployment, scaling, and management of containerized application. As it is an open source and free so if we need to create a project in this technique then it is get hosted by CNCF (Cloud Native Computing Foundation). We are having many versions of it, but the recent version used is v1.21, which was get released in 2021 and completely enriched with 51 enhancements with respect to older versions. Out of these enhancement 13 enhancements were found to have graduated to stable, 16 are moving to beta version, 20 enhancements are entering alpha, and 2 features have been deprecated.

Types of Application Deployment:

Physical Deployment:

In Contrast to earlier days the deployment of work was very tedious and tuff.  So, we are using the server client application and the organizations were using the traditional Physical Server for deploying the application. In such case there was a limitation that we don’t have any way to define the resource boundaries in a physical server for the respective application, and it may get caused resource allocation issues which is very difficult to get manage.

Virtual Deployment:

After this the new technique were get used called the “Virtualised deployment”. In this technique it mainly allows to run multiple Virtual Machines (VMs) on a single physical server's CPU. It is the most event driven technique where we could be able to run various kind of application easily. It should be get noted that the Virtualization deployment technique also allows the applications to be isolated between VMs. During the process it is also used to provide a level of security as the information of one application cannot be freely accessed by another application. No doubt, it provides many advantages such as 

• The Virtualization deployment technique allows better utilization of resources and scalability as here the application can be added or updated easily.
• It reduces hardware costs, as everything is virtually assembled.
• Using this technique, we can present a set of physical resources as a cluster of disposable virtual machines. 
• It is secure and good. 

But the biggest disadvantage of the respective technique was that it is very tuff to configure and sometimes we may get compatibility issues.

Container Deployment:

In contrast to Virtual Deployment technique if we are going to analyse the Container Deployment then they are much similar to VMs deployment, but they used to provide us the following benefits such as

• It is used to provide us a isolation properties to share the Operating System (OS) among the applications. This approach was mainly don’t have in VMs. 
• Container’s deployments are considered as lightweight. 
• Every container has its own filesystem, which is allowed to get share of CPU, memory, process space, and more. 
• They are used to provide decoupled from the underlying infrastructure.
• They are portable across clouds and OS distributions.

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In addition, with this the container approach also provides the other benefits such as

• It supports the feature of Agile application creation and deployment.
• It provides a Continuous development, integration, and deployment of application layers.
• It supports the Environmental consistency across development of application, their testing, and production in the meanwhile.
• It is used to have the Application-centric management approach which is very useful.
• It is Loosely coupled, distributed, elastic, liberated micro-services.
• It provides better Resource isolation and utilisation.

Why Kubernetes and what it can do: 

As per the benefits point of view the Containers deployment technique are a good way to bundle and run your applications but the biggest limitation related to downtime. It means if a container goes down due to any reason, then we need another container to get start as soon as possible. But starting of another container wouldn't be get easier if this behaviour was handled by a system. Hence to overcome from such problem the Kubernetes is come into picture to provide the rescue. It is used to provide us a framework to run distributed systems resiliently. It also provides the better scope for scaling and failover for application, their deployment patterns. It can easily manage a canary deployment for your system which is a great advantage of Kubernetes.

Kubernetes Modules:

As we have already discussed above that the Kubernetes is basically used to provide a framework to run distributed systems resiliently. It also provides the better scope for scaling and failover for application, their deployment patterns. To do this in the effective manner it used to provide some basic modules such as

Kubernetes Basics Modules

As per the modern requirement we do have all functionality. As accordance with modern web services, the users usually expect that the applications to be get available 24/7, and developers expect to deploy new versions of those applications several times a day. As we have already discussed that the Containerization is a good approach, and it merely helps the package software to serve these goals and try to enable the applications to be released and updated without downtime. 

But when we are going to consider the Kubernetes with regards to Containerization then it basically used to help us to make those containerized applications run in efficient manner and the where and when you want and helps them find the resources and tools they need to work. It should be get noted that the Kubernetes is a production-ready, open-source platform designed with Google's accumulated experience in container orchestration.

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How to start on Kubernetes:

As stated above if you need to get start with Kubernetes then you need to proceed with the following basic steps. 

1. Create a Kubernetes cluster.
2. Deploy an app.
3. Explore your app.
4. Expose your app publicly.
5. Scale up your app.
6. Update your app.

When we are going to create a cluster using the Kubernetes then it is used to coordinates a highly available cluster of computers which are get connected to work as a single unit.  The abstractions in Kubernetes allow you to deploy containerized applications to a cluster without tying them specifically to individual machines. We can also use the Minicube to create a cluster.

Kubernetes Deployments:

When the Kubernetes cluster are get running fine then we need to deploy our containerized applications on top of it. To do so, we need to create a Kubernetes Deployment configuration. The Deployment process is basically get used to instructs Kubernetes about the creation and updating of instances of our application.

Once the application instances are get created successfully then the Deployment Controller continuously monitors those instances. For suppose If the Node hosting an instance goes down or is deleted accidently, then the controller is got ready to replaces the instance with an new instance of another Node in the cluster

Once it is get deployed then as per the process get informed earlier we need to explore the application by using the viewing the pods and Nodes. It should be get noted that the Pods is a Kubernetes abstraction approach to represents the group of one or more application containers. It used to provide the features such as:

• Shared storage, as Volumes.
• Networking, as a unique cluster IP address.
• nformation about how to run each container. 

Similarly, the Nodes are also used along with Pods. A Node in Kubernetes is get defined as a worker machine which may be either a virtual or a physical machine which depends on the cluster and get managed by the Master Node. Remember, a Node can have multiple pods, and the Kubernetes master automatically handles scheduling the pods across the Nodes in the cluster. 

The rest of the stages such as Expose your app publicly, scale up your app, and update your app are the secondary stages which is get required as per our requirement. Here we are using the Service and Labels where the Service is used to routes the traffic across a set of Pods. They are the abstraction which allows the pods to die and replicate in Kubernetes without impacting your application. Similarly, the Labels can be attached to objects at creation time or later on. They can be modified at any time.

Major Themes of Kubernetes 1.21:

As we have already discussed that it is an open-source container orchestration engine which is being used for automating deployment, scaling, and management of containerized application, so it supports many themes as its part of action. Such as

1. CronJobs Graduate to Stable: It is a beta version form version 1.8. It is basically used for performing regular scheduled actions such as backups and report generation. But here each of the task has to be get configured to get recur indefinitely.
2. Immutable Secrets and ConfigMaps: It is basically used to provide a resource type that we are going to use in our application. It should be get noted that the Secrets and ConfigMaps by default are mutable. They are beneficial for pods that are able to consume changes. They are mainly get used when we want that later our application is not got change. Mutating Secrets and ConfigMaps can also cause problems if a bad configuration is pushed for pods that use them. 
3. IPv4/IPv6 dual-stack support: As we know that the IP addresses are a consumable resource using which the cluster operators and administrators need to make sure are not exhausted. It should be got note that the public IPv4 addresses are now scarce. So, we are now going to use the dual-stack support which is basically get used to enables the native IPv6 routing to pods and services. The Dual-stack cluster networking also improves a possible scaling limitation for workloads which becomes the more beneficial factor for most of the relevant problems in the network.
4. Graceful Node Shutdown: It is also supported by the beta version and is very beneficial feature like other. It is basically get used to allow the kubelet to be aware of node shutdown process abnormally and gracefully terminate pods that are scheduled to that node for the operation. 
5. Persistent Volume Health Monitor: As the name implies, they are basically get used for monitoring purpose. They are mostly get used in applications to get local, file-based storage. If we need to use them in different manner, then this provision is also available in the scenario. In some special cases when the users need to migrate their applications without re-write the storage backends cases then they are very helpful.
6. Reducing Kubernetes Build Maintenance: If we are going to have a review to previously Kubernetes versions then it has maintained multiple build systems. Over the last release cycle, the current version has a lot of works has been put and get implemented to simplify the existing errors and the build process and standardize on the native Golang build tools. Using the current This should empower broader community maintenance and lower the barrier