What is Kubernetes? | green plus

What is Kubernetes?

In simple words, Kubernetes (aka. K8s) automates many of the processes involved in deploying, managing, and scaling containerized applications. But that’s what it does and not what it is. In fact, Kubernetes is an open-source container orchestration platform. This means it helps the organization/company to cluster together groups of hosts running Linux® containers and manage them easily and efficiently. This may answer one or two of your questions, but no you probably ended up having more questions at this point. Here are some of them that we assumed the reader needs the answer to.

What is a Kubernetes cluster?

A set of nodes that run containerized applications. Containerized applications are applications that run in a container (isolated runtime environments). These isolated environments encapsulate an application with all its dependencies, including system libraries, binaries, and config files. Containers are more lightweight and flexible than virtual machines. Thus if the containerized applications use Kubernetes, development, movement, and management of the applications can become much easier.

Kubernetes clusters let containers run across multiple machines in different environments – such as physical, cloud-based, virtual, and on-premises. K8s containers – unlike virtual machines – are not limited to a specific operating system. They can share operating systems across machines and run on various operating systems simultaneously.

The structure of Kubernetes clusters

API server: It exposes a REST interface to all the resources. In other words, it is the front end of the K8s control panel.

Scheduler: Checks the required resources and metrics of each container and places them accordingly. Checks Pods to ensure that they are assigned to a node. If not, it will select the nodes for them so they can run on them.

Controller manager: Runs controller processes. Reconciles the cluster’s initial state with its desired specifications. And manages controllers such as replication controllers, node controllers, and endpoint controllers.

Kubelet: Makes sure that each container is running in a Pod. This is done by an interaction with the Docker Engine. Docker Engine is the default program for creating and managing containers. We won’t dive too deep into this process as it makes the article complicated and is not relevant enough to the title anyway.

Kube-proxy: Maintains network rules across nodes and manages network connectivity. It implements the “Kubernetes Service” concept in all nodes of the cluster.

ETCD: Stores all the data of a given cluster.

What is container orchestration?

Containerized workloads and services require a lot of operational effort to run well. With container orchestration, a big part of the required work to run such services will be automated. Without that, those works should be done manually; which takes more time, more human resources, and more money.

Containers are ephemeral. Running them in production can easily become a challenge due to the high amount of required effort. If one pairs them with micro-services – which usually run in their own individual containers – this can easily lead to having a big tree of thousands of nested containers. This can be the main reason why a large-scale system needs to automate tasks such as the management and scaling of containerized applications. Kubernetes is one of the best solutions for this problem. And here is why:

Why should we use Container Orchestration?

Simply saying, the key to working with containers is container orchestration. With it, an organization can unlock the full benefit of containers. In addition to this benefit, orchestration has its own benefits as well:

Simplifying the operations: Literally the most important benefit of container orchestration and the main reason why Kubernetes adopted it. As said, the amount of complexity containers have is not controllable without orchestrating them.

Boosting resilience: Orchestrating containers allows them to automatically restart or scale (up or down), increasing the resilience of them significantly.

Adding more security: The automatic nature of container orchestration allows containerized applications to get rid of human errors by eliminating the need for manual management of the container. Thus increasing security and stability.

What are containers?

Containers are a method to build, package, and deploy softwares. Although they are not exactly the same thing, they are still similar to virtual machines (VMs) regarding their use case. One of the most important differences is the fact that containers are isolated and abstracted away from the infrastructure and the underlying operating system that they are running on. Or in simpler terms, a container, in addition to the application itself, also includes everything that the code requires to run properly. This is how it is isolated from the OS and the rest of the infrastructure.

But why do we have to do such a thing? Well, this isolation has several benefits which some of them are:

Portability: As you might already have guessed, the main benefit and the main reason to use containers is that they make the application portable. They are built to run in any environment. This makes containerized apps and workloads easier to move between different cloud platforms. One of the ways it achieves this simplicity is that there is no need to rewrite a large part of the application in order to port it to a new operating system and or a new cloud platform. In fact, the application does not care that much about the platform as it is isolated from it anyway.

Simplifying the development: Containers remove the need to ensure that the application is compatible and works properly across all platforms. This saves a lot of time for developers, letting them spend it on the core of the application. And making it easier and faster to patch issues and merge pulls without making extra development branches for each platform.

Reducing resource utilization and Optimizing the execution: As said, containers are lightweight. It allows a single machine to solely run many of them at the same time. Saving resources and optimizing the execution of the app.

Kubernetes advantages

Kubernetes is all about optimization. By automating many of the DevOps processes, it gets rid of the necessity of manually doing them. K8s services provide load balancing and simplification of container management on multiple hosts. It makes it easy for an enterprise to provide wider scalability, more flexibility, and better portability for its apps. By its automatically managed containerization, it saves the time of the software developers to better it spend for productive development.

In fact, after Linux, Kubernetes is the fastest-growing open-source software project in history (link to https://www.cncf.io/reports/kubernetes-project-journey-report/) according to a 2021 study by the Cloud Native Computing Foundation (CNCF). Numerically speaking, the number of Kubernetes engineers grew by 67 percent to 3.9 million from 2020 to 2021. This means 31 percent of the whole 12.6 million backend developers in the world were Kubernetes engineers in 2021.

But this is not all of the benefits of Kubernetes. The following is a list of the top 7 benefits of using Kubernetes:

Container Orchestration savings

Many types and sizes of companies found themselves saving on their ecosystem management by automating manual processes using K8s. Kubernetes automatically provisions and fits containers into nodes to utilize various resources in the best way possible. Some public cloud platforms calculate the management fees in relevance to the number of clusters used by the application and its workload. This means running fewer clusters can reduce the number of API servers and other redundancies in use. Leading to less overall fees and the saving of money. So it saves on developer operations, resource usage, and money. The first two actually also save money indirectly.

After configuring Kubernetes clusters, apps will run with minimal downtime and maximal performance. They will require less support when a node or pod fails as K8s can repair most problems automatically and without human interference. This container orchestration solution increases workflows’ efficiency by getting rid of the need for doing repetitive processes. This not only leads to needing fewer servers but also reduces the clunkiness of and increases the efficiency of administration.

Increasing DevOps efficiency (especially for microservices architectures)

Development, deployment, and testing of an application across multiple cloud platforms with different environments – operating systems and infrastructures – is not an easy task. Implementing microservices architectures in such ecosystems can make things even harder. A developer team should constantly check every platform and environment they use to ensure that the application is running correctly, efficiently, and safely. Such multi-platform ecosystems can lead to an extremely branched development roadmap with a lot of repetitive tasks and QAs for each platform. All these issues make creating virtual machines inefficient and illogical compared to instead creating containers; Specially orchestrated containers.

This is a literal disaster for a development team. So the sooner a dev team deploys Kubernetes during the development cycle, the better. The sooner they do it, the fewer will be mistakes down the road as they can test the code early on. They waste less time scrimmaging with traditional solutions such as virtual machines.

Apps based on microservices architecture are made of separate functional units that communicate with each other through the APIs. This makes the IT department of an organization able to separate itself into small teams, each working on single features, which leads to more efficiency in the end.

Deploying apps and workloads in multi-cloud environments

Thanks to Kubernetes, workloads can exist in a single cloud or be on multiple could services no matter what, and easier than ever. Kubernetes clusters allow the migration of applications from on-premises infrastructures to hybrid deployment across any cloud provider’s cloud. No matter if the cloud is public or private. no matter what operating system it is using. It just works; Without losing any of the performance and functionalities of the application. This lets an enterprise or an organization easily move their workload or application to a closed source or proprietary system without facing any lock-in in the process. GreenWeb offers straightforward integrations with Kubernetes-based applications with no need to refactor the code in most cases.

More portability – Less vendor lock-in

Using containers for your app is more agile to handle and more lightweight for handling virtualization than virtual machines. That is because containers only contain the resources that the application actually needs. For the rest, it uses the features and resources of the host operating system thanks to its abstract nature. Containers are smaller, faster, and easier to port as already mentioned. For example, using four virtual machines to host four applications requires four instances of a guest operating system to run on that server. But using containers as the approach means the developer can contain them all within a single container where they share one version of the host OS.

Automating deployment and scalability

Kubernetes schedules and automates container deployment across multiple compute nodes. It does not matter if it is on a public cloud, on-site virtual machines, or physical on-premises machines. Its automatic scaling feature allows teams to scale up or scale down the application effortlessly to faster meet the demand. Automatic scaling starts up new containers on demand when a heavy load or a spike happens. It observes the CPU usage, memory allocations, and other custom metrics in real-time to find the demand for higher computing power. As an example, in times of online events – such as Black Friday offers in an online shop –  the requests increase massively in a second, making manual management inefficient. When the demand spike is over, K8s automatically scales down resources to avoid wasting resources. But it can also roll back as fast as possible if something goes wrong.

Improving apps’ stability and availability in a cloud environment

Kubernetes automatically places and balances containerized workloads and appropriately scales the cluster to accommodate the increase and decrease of demand and keep the system live and efficient. This lets the developers run their containerized applications more reliably. If one node of a multi-node cluster fails, K8s automatically redistributes the workload to other nodes without disrupting the availability of the application to users. It also has self-healing features such as restarting, rescheduling, and or replacing a container when it fails or when a node dies. It allows developers and engineers to roll updates and patches without downing the app.

Being open-sourced

Kubernetes is a project led by a community rather than a company with limited human resources and knowledge base. It is fully open source, which means the developers can customize it however they want. And more importantly, it means the solution is free for everyone, forever! The open-source license allows it to have a huge ecosystem of other open-source tools and plug-ins designed to use with it. The platform’s strong support means there is constant innovation and improvement to K8s, which protects your free investment in the platform. It means you are not locked into a technology that may become outdated anytime soon.

Kubernetes history and ecosystem

Announced by Google in mid-2014, Kubernetes was created by Joe Beda, Brendan Burns, and Craig McLuckie. Very soon, other Google engineers joined them, including Tim Hockin. The development and the design of Kubernetes were influenced by Google’s Borg cluster manager. In fact, many of the developers of K8s had previously worked on Borg. The seven-spoked wheel logo of it is inherited from its initial name, Project 7 – from the Star Trek’s ex-borg character Seven of Nine -. Kubernetes is written in Golang (Google’s alternative to C++).

Released on July 21, 2015, Kubernetes continued its development as a seed technology in the Cloud Native Computing Foundation (CNCF); A foundation formed by Google in collaboration with the Linux Foundation. In February 2016, the Helm package manager was released for Kubernetes.

Although Google was already offering managed K8s services, and Red Hat was also supporting it – as a part of the OpenShift family – since the announcement of the Kubernetes project in 2014, In 2017, the others rallied around it and announced adding native support for Kubernetes via cluster managers such as Pivotal Cloud Foundry (VMWare), Marathon and Mesos (Mesosphere), Docker (Docker, Inc.), Azure (Microsoft), and EKS (Amazon Web Services).

As of March 6, 2018, Kubernetes was the 9^th project in the list of projects with the highest number of commits in GitHub, and 2^nd in the list of issues (Issues let you track your work) as well as the list of the number of authors; Placing it right after the Linux kernel.

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