An Introduction to Kubernetes And Containers

Kubernetes is a sophisticated open-source technology created by Google that is used to manage containerized applications in a clustered environment. It strives to improve the management of connected, dispersed components, and services across various infrastructures.

What is Kubernetes?

Kubernetes is a free and open-source system for managing containerized loads and functions, with declarative configuration and automation features. It has a wide and quickly expanding ecology. Services, support, and tools for Kubernetes are widely accessible. 

Kubernetes is a Greek word that means “helmsman” or “pilot.” The acronym ‘K8s’ is derived by having to count the eight letters between the letters “K” and “s”.

Kubernetes combines over 15 years of Google experience in scaling production workloads with the best community ideas and practices. Learning more about Kubernetes will be a lot easier through a comprehensive online DevOps program that will also help you learn all the associated tools and technologies widely used in the DevOps practice. 

Containers essentially create a virtual host operating system (or kernel) and separate the needs of an application from other containers operating on the same computer. Prior to containers, if you had many apps launched on the same virtual machine (VM), any modifications to shared dependencies may cause weird things to happen. Hence it was common practice to have one application per virtual machine.

The method of one application per VM solved the problem of conflicting dependency isolation, but it burned a lot of resources (CPU and memory). This is because a VM runs not just to your program but also to a whole operating system, which requires resources as well. Therefore, there will be fewer resources available for your application to use.

What can you do with Kubernetes?

Here are some examples of what you are able to do with the help of Kubernetes:

• Execute contemporary applications across many clusters and infrastructures on cloud services and private data centers
• Ensure that development teams have uniform, unchangeable infrastructure from design to production for each project
• Load balancing and service discovery
• Storage synchronization
• Container-level resource administration
• Rollback and deployment automation
• Management of container health
• Management of secrets and configuration

The Kubernetes Architecture

The Kubernetes architecture is a good example of a distributed system that has been well planned. It treats all of the computers in a cluster as a single resource pool. It performs the functions of a distributed operating system by successfully managing to schedule, distribute resources, monitor infrastructure health, and even preserve the intended condition of infrastructure and workloads.

Kubernetes, like any other sophisticated distributed system, has two layers: head nodes and worker nodes. The control plane, which is in charge of scheduling and controlling the life cycle of workloads, is generally managed by the head nodes.

Once an application or service has been built, the next stage in conventional app development is to deploy it, which may be a difficult and time-consuming process. This is due to the fact that a successful app deployment involves a plethora of meticulous setups, ranging from resource allocation and dependency management to configuring environmental variables.

Another factor to consider is the application’s portability. If a developer has to alter the deployment environment or switch to a different cloud provider, then he/she must restart the deployment process from the beginning. Again, this is a time-consuming and difficult procedure that may result in:

1. Drifts in configuration 
2. Production flaws

Containers effectively handle this issue by encapsulating the application code base as well as any dependencies (such as runtime, system tools, configuration files, and libraries) in a package known as container. The container image is created as a result of this containerization. It is a lightweight, safe, and immutable package.

This image may then be used to launch a containerized application in any environment, giving developers the flexibility to work without regard for environmental limitations.

Pods 

A Kubernetes pod is a collection of containers and the smallest unit that Kubernetes manages. Pods have a single IP address that is shared by all containers in the pod. Containers in a pod share resources like memory and storage.

This allows the various Linux containers within a pod to be viewed as a single application, much as if all of the containerized processes were operating on the same host under more typical workloads. When the application or service is a single process that must run, it is extremely typical to have a pod with simply a single container.

However, as things become more sophisticated and numerous processes must collaborate utilizing the same shared data volumes for proper operation, multi-container pods simplify deployment settings when compared to setting up shared resources amongst containers on your own.

Deployment

What is Kubernetes deployment? Kubernetes deployments enable you to define how pods should be duplicated among your Kubernetes nodes, which determines the scale at which you want to run your application. Deployments specify the number of identical pod replicas to be operated as well as the chosen update mechanism to be followed when upgrading the deployment. Kubernetes will monitor pod health and delete or add pods as required to bring your application deployment up to speed.

Services

An individual pod’s lifespan cannot be counted on. Everything from its IP address to its very survival is subject to change. Indeed, among the DevOps community, there is a belief that servers should be treated as either “pets” or “cattle”. Similarly, Kubernetes does not treat its pods as distinct, long-running instances. If a pod meets a problem and dies, it is Kubernetes’ responsibility to replace it so that the application does not experience any downtime.

Cloud Service Models

The three most essential cloud service models are PaaS, SaaS, and IaaS.

• PaaS Platforms

In this case, your cloud provider offers you a comprehensive platform to use. When we say “full platform to utilize,” it means that the supplier handles all of the infrastructure’s underlying components. For example, your servers and virtual machines are taken care of and you are provided with some preset tools to construct your apps.

SaaS is an abbreviation for Software as a Service.

It means that a cloud provider is providing you with entire software, such as servers, databases, and application codes, in the form of service. Gmail, for example, allows you to exchange e-mails without bothering about what is going on in the background. 

All you should do is compose your e-mail and it will be delivered to the place or person you specify. You are unconcerned with how the platform works, what the security risks are, what happens if the server goes down, or where the message is kept; none of this is of relevance to you. Because, the service provider gives you a full program or application in the form of service. This architecture is known as Software as a Service.

• Containers as a service (CaaS)

It is a cloud service that lets software developers and IT departments use container-based virtualization to upload, organize, operate, scale, manage, and stop containers. A CaaS provider will often provide a framework that allows customers to access the service. Application programming interface (API) calls or a web portal interface is commonly used by providers.

What is Docker?

Docker is a free and open platform for creating, delivering, and operating applications. Docker allows you to decouple your apps from your infrastructure, allowing you to release software more quickly. Docker allows you to manage your infrastructure in the same manner that you control your apps. 

You may drastically minimize the time between developing code and executing it in production by utilizing Docker’s methodology for fast shipping, testing, and deploying code.

Docker allows you to bundle and execute a program in a container, which is a loosely separated environment. Because of the isolation and security, you may run several containers on a single host at the same time. 

Containers are lightweight and include everything needed to run the program, eliminating the need to rely on what is already installed on the host. Simply sharing containers while working ensures that anyone with whom you share gets the same container that acts in the same way.

Docker is built on a client-server model. The Docker client communicates with the Docker daemon, which is in charge of constructing, operating, and disseminating your Docker containers.

Docker client and daemon can operate on the same machine or a Docker client can connect to a distant Docker daemon. The Docker client and daemon communicate via UNIX sockets, REST API, or a network interface.

Docker Compose is a client of Docker that lets you work with applications composed of a set of containers. Docker Desktop features an independent Kubernetes host and client, as well as computer-based Docker CLI integration. The server of Kubernetes is a single-node cluster that runs in your Docker container. 

The Kubernetes server is exclusively for local testing and operates within a Docker container on your local machine. By enabling Kubernetes, you may deploy your workload in parallel, on Kubernetes, Swarm, or as standalone containers. The operation of enabling or deactivating the Kubernetes server has no effect on your other workloads.

Use Cases of Kubernetes

Kubernetes Engine by Google

Kubernetes originally appeared on Google Cloud in 2014. Google created the technology to containerize its workloads over the last 15 years. When it revealed that it was an open-source tool, it opened the door for the community to contribute to it.

Kubernetes increases a company’s reliability and minimizes a resource’s time and effort by providing automated container orchestration.

Google continues to utilize Borg internally and Kubernetes serves as a third-party container orchestration solution. The goal of developing Kubernetes was to learn from prior failures and improve the design.

Kubernetes was never intended to replace Borg since it would have required an enormous amount of effort for the developers to convert. As a result, engineers learned from their previous experiences and created an open-source version on which other organizations may rely.

Google Kubernetes Engine (GKE) is a secure and managed service that supports multi-cluster deployments and auto-scaling in four directions. Companies such as Pizza Hut USA rely largely on Google solutions such as GKE. They used the technologies to improve their eCommerce infrastructure and order response time.

Kubernetes and Pokemon GO

Niantic Inc. created and released Pokemon GO. The game has received over 500 million downloads and has over 20 million active users. The creators did not anticipate such an exponential surge in consumers, which was well beyond their predictions.

They quickly recognized that the servers could not manage the volume of traffic. The application was then launched on GKE, which could orchestrate their container cluster at a reasonable size.

This allowed the team to concentrate on providing live modifications to its users. GKE assisted the firm not only in serving by helping Niantic to better its user experience but also in adding extra features to the program.

Advantages of Kubernetes 

• Kubernetes allows you to run several containers concurrently. A developer constructs a ‘Deployment’ for these containers and specifies the number of replicas. A set of instructions that humans can readily understand is then supplied.
• Because Kubernetes is supported by numerous cloud infrastructures. It can run on nearly any public cloud, on-premise hardware, or even bare metal.
• It saves money by optimizing infrastructural resources and utilizing hardware efficiently for businesses that use K8s.
• It regularly monitors the health of nodes and containers.

Kubernetes Simple Alternative

What are some Kubernetes alternatives? 

1. Amazon Web Services Fargate

AWS Fargate is a serverless computing technology that complements Amazon Elastic Container Service (ECS). It enables you to run containers without needing to manage servers or Amazon EC2 instance clusters. 

Fargate features a flexible computing paradigm that does not need you to choose an instance type or construct your cluster manually. It scales up invisibly and you only pay for the CPU and memory resources you really utilize.

Fargate is appropriate for isolated services, basic microservices applications, or distributed systems such as batch processing that do not require tight contact between components because it lacks orchestration features.

2. Azure Kubernetes Service

Azure Kubernetes Service (AKS) simplifies the deployment of managed Kubernetes clusters to Azure. AKS delegated administration of Kubernetes to Azure, minimizing management complexity and operational overhead.

AKS maintains Kubernetes hosts on Azure VMs and handles ongoing duties such as health monitoring and maintenance. Unlike comparable services on AWS and Google Cloud, AKS charges just for Kubernetes worker nodes and provides free master nodes and cluster administration.

Kubernetes has emerged as the de facto container orchestration platform. It is supported by all of the major cloud providers, making it the obvious choice for enterprises wishing to move more applications to the cloud.

Knowing about Kubernetes allows you to have a more comprehensive understanding of the complete development lifecycle. In bigger companies, development is often viewed as authoring, reviewing, and merging code, after which a CI pipeline “deploys” it.

Kubernetes is a key part of agile software development because it allows DevOps teams to manage virtual machine (VM) clusters. Are you interested in learning more about this technology? Enroll in a DevOps certification course to be a master in this field.