Kubernetes has emerged as one of the most exciting technologies in the world of DevOps that has gained a lot of attention of the DevOps professionals. Kubernetes, or commonly known as k8s, is an open source, portable and extensible platform, for managing containerized workload and services. This container orchestration system is put to automating the deployment, scaling, as well as management of the application.
As one of the top DevOps tools, the primary aim of Kubernetes is to provide a platform that allows streamlining of deployment, scaling, and operations of application containers across a cluster of hosts. Plenty of cloud services provide Kubernetes based platform as a service (PaaS) as well as infrastructure as a service (IaaS).
Currently, Kurbenetes works with a plethora of tools like Docker. Kubernetes has helped in optimizing the app development for cloud, and naturally, many professionals are driven to learn Kubernetes and excel in it. In this article, we’ll help you understand the basics of Kubernetes through an introduction to Kubernetes
Introduction to Kubernetes
The introduction to Kubernetes first happened in the year 2014, by none other than the technology giant Google. A few Google engineers worked upon it, alongside Brendan Burns, Joe Breda, and Craig McLuckie. The design and development of Kubernetes relied heavily upon the Borg System of Google. Incidentally, a majority of the contributors had already worked upon Borg.
The project was initially given the name of Project Seven of Nine, based on a Star Trek reference. The logo contains seven spokes, which stand for that codename. They used C++ language to write the original Borg project. However, the rewritten system is implemented in Go. Kubernetes v1.0 was introduced in 2015 for use. Google, along with the release, decided to partner with Linux Foundation.
Together they formed the Cloud Native Computing Foundation, and Kubernetes was on offer as a seed technology. By March 2018, Kubernetes reached the 9th place in commits at GitHub and 2nd in authors and issues to Linux Kernel.
What are the Kubernetes objects?
It is essential to learn Kubernetes objects to understand how Kubernetes works. The Kubernetes operates as a set of building blocks that that collectively provide a mechanism for applications. It is extensible and loosely coupled to meet up the different workload expectations. The Kubernetes Objects are the resources that help to exert control over the computer and storage resources.
The key objects are:
- Pods: Pod is the basic scheduling unit of a Kubernetes. A single pod can consist of a single or even more container that are co-located on the same host machine and can easily share resources. It can add a higher level of abstraction by grouping containerized components. Each pod also has a unique Pod IP address.
- Services: A set of pods, that can work together, as one tier or even multi-tier is known as Kubernetes services. Kubernetes can provide two modes of service discovery, using Kubernetes DNS or using environmental variables.
- Volumes: In the Kubernetes container the filesystems provide ephemeral storage. It implies that upon restarting the container will wipe out the data, making the storage very limiting. However, the Kubernetes volumes provide lifelong storage in the pod itself.
- Namespaces: To ensure that the non-overlapping of resources, Kubernetes provides a partition known as namespaces. They can be used in the case of many users, teams, or projects.
How does Kubernetes work?
The Kubernetes has a primary/replica architecture. Kubernetes architecture consists of a lot of components. These components can be divided into the ones that manage an individual node, and the others are a part of the control plane. It is essential to understand the architecture if you wish to learn Kubernetes.
Key areas of Kubernetes architecture are:
A node is a machine which deploys the workloads or containers. It is also commonly referred to as a Minion or Worker. Each node is the cluster needs to run a container runtime like Docker. Apart from that, it requires a series of other components for easy communication with the primary, for network configuration of these components. The other components are:
- Kubelet: A kubelet is a component that ensures that each node is in a running state and that all the containers are healthy. The process of stating, stopping, and maintaining application containers is taken care by kubelet. It monitors the state of the pod, and if they are not in the desired state, the pod re-deploys the same node.
- Kube-proxy: The Kube-proxy handles the implementation of a load balancer and a network proxy. The primary aim of this component is to route traffic to the right container on the basis of IP and port number.
- Container runtime: A container resides inside the pod. A container is the lowest level of micro-services. It ideally holds running applications, libraries, and their dependencies.
Kubernetes Control Plane:
The primary or the control plane is the major component of the Kubernetes architecture. It is responsible for managing the workload and directing the communication across the systems. The control plane consists of various parts, each having its own process. They can run either on a single primary node and also on multiple primaries supporting high-availability clusters. The various components are:
- etcd: etcd is a data store which a CoreOS can develop. It is lightweight, persistent, distributes, and stores key-value configuration data.
- API Server: The API server is yet another important component of the Kubernetes. It server Kubernetes using JSON, over HTTP. The API can provide for both the internal and external interface to Kubernetes.
- Scheduler: A schedule is a pluggable component which selects which node an unscheduled pod will run on, based upon the resource availability. It is the duty of the scheduler to make sure that the workload is not scheduled in excess of the available resources.
- Controller Manager: A controller is a reconciliation loop, that works to drive actual cluster state towards the desired cluster state. It is ensured by the management of the set of controllers.
The add ons are run through pods and services, and they operate just like any other application that is running in a cluster. The only underlying difference here is that they implement the features of Kubernetes cluster. The few important add ons are:
- Web UI
- Container resource monitoring
- Cluster-level logging
Kubernetes certifications are among the top 5 DevOps certifications. Read our previous blog to know about Top DevOps Certifications.
What are the Uses of Kubernetes?
The production of real apps can span across multiple containers. These containers need to be deployed across multiple server hosts. Here, the problem arises that of the security for containers being multi-layered and complicated. Kubernetes come to the rescue here. It easily provides the management capabilities and orchestration which is required to deploy the containers at a scale. The orchestration allows one to build application services that can span over multiple containers, schedule these containers over clusters, scale these containers, and manage the health of these containers as well. By learning Kubernetes and using them, you can easily ensure IT security.
For better functioning, Kubernetes needs to be integrated with various other components as well. They are storage, network, security, telemetry, and many others. Only then it can provide a comprehensive and complete infrastructure.
Kubernetes can also fix many problems with container proliferation. It refers to the sorting of containers together in a pod. The pod adds a layer of abstraction to the grouped containers, which can help in scheduling workload and providing necessary services to these containers, like storage and network. Other components of the Kubernetes can help with loading the balance across these pods. They make sure that you have the right number of containers which are running to support the workloads.
What are the Advantages of Kubernetes?
With the introduction of Kubernetes, the developers enjoy many benefits. Majorly, it provides the platform to schedule and also runs a container on clusters of physical or virtual machines. Furthermore, it can also help in fully implementing and relying on the container based infrastructure. Since the Kubernetes runs on automation od the operational tasks, it allows you to do the same things like other platforms, but for the containers.
Some major advantages to learn Kubernetes are:
- Make better use of the hardware to maximize the resources needed to run enterprise apps
- Orchestrate containers over multiple hosts
- Mount or add storage to run apps
- Control and automate application deployment
- Scale the containerized applications
- Health check and also self-heal the apps
How to Learn Kubernetes?
If you pose a keen interest in learning Kubernetes, and to make use of the technology, you can avail proper tutorials. The tutorial covers all the basic of the Kubernetes orchestration systems. It includes a few modules which contain background information about the features, concepts, and also offers an interactive online study material. This tutorial will help a candidate to lean Kubernetes, and master the task of managing a simple cluster, and also the containerized applications.
The online tutorials teach about:
- Deploying a containerized application on a cluster
- Scale the deployment
- Update the application with a new version of the software
- Debug the containerized application
The candidate can find plenty of online courses that can enlighten them about the Kubernetes. To learn Kubernetes, you can visit these sites and gain expertise in the concept. You can find them on Linux Academy, KodeKloud, Coursera, Katacoda, Udacity, and many more.
Though the concept of containers has existed for over a decade now, its popularity is only recent. Mainstream Unix-based operating systems had built-in support for the containers, but it was truly only Docker that could democratize the containers by making them accessible and manageable. Kubernetes is based on 15 years worth of experience of running production workloads at Google.
The container orchestration has significantly impacted each and every aspect of the modern day software development and deployment. Kubernetes plays a major role in driving the adoption of containers in both successful enterprises as well as emerging startups.
If you want to learn Kubernetes and give your DevOps career a new edge, join Kubernetes online course and become an expert of Kubernetes with AWS and Docker.
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