What exactly is Kubernetes?

This article provides an introduction to Kubernetes.

Kubernetes is an open source framework for managing containerized workloads and services that allows for declarative setup as well as automation. 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." K8s is derived from counting the eight letters between the letters "K" and "s." In 2014, Google made the Kubernetes project open source. Kubernetes blends over 15 years of Google expertise running production workloads at scale with best-of-breed community ideas and practises.

Let's go back in time to see why Kubernetes is so beneficial.

Evolution of deployment

Traditional deployment model: Historically, corporations operated programmes on physical servers. In a physical server, there was no method to set resource boundaries for apps, which produced resource allocation difficulties. For example, if numerous apps operate on a physical server, one programme may consume the majority of the resources, causing the other applications to underperform. One alternative would be to run each programme on a separate physical server. However, this could not grow since resources were underused, and it was costly for corporations to maintain a large number of physical servers.

Virtualized deployment era: Virtualization was introduced as a solution. It enables you to operate several Virtual Machines (VMs) on the CPU of a single physical server. Virtualization allows programmes to be segregated amongst VMs and offers a measure of security by preventing one application's information from being easily accessible by another.

Virtualization improves resource usage in a physical server, improves scalability because applications can be quickly added or changed, lowers hardware costs, and much more. You may offer a collection of real resources as a cluster of disposable virtual computers using virtualization.

On top of the virtualized hardware, each VM is a whole computer with all of its components, including its own operating system.

Container deployment era: Containers are comparable to virtual machines (VMs), but they feature more relaxed isolation attributes to allow applications to share the operating system (OS). As a result, containers are considered light. A container, like a virtual machine, has its own filesystem, CPU, memory, process space, and other resources. They are portable between clouds and OS distributions because they are isolated from the underlying infrastructure.

Containers have grown in popularity because they bring additional benefits such as:

Agile application design and deployment: container image generation is easier and more efficient than VM image creation.

Continuous development, integration, and deployment: allows for consistent and frequent container image construction and deployment, as well as rapid and efficient rollbacks (due to image immutability).

Separation of concerns in development and operations: construct application container images at build/release time rather than deployment time, isolating apps from infrastructure.

Observability: displays not just OS-level information and metrics, but also application health and other signals.

Environmental consistency throughout development, testing, and production: Works on a laptop and on the cloud.

Portability of cloud and OS distributions: Runs on Ubuntu, RHEL, CoreOS, on-premises, major public clouds, and anyplace else.

Application-centric management: Increases the level of abstraction from running an operating system on virtual hardware to running an application on an operating system utilising logical resources.

Loosely linked, distributed, elastic, freed micro-services: applications are divided into smaller, independent components that can be dynamically deployed and managed – not a monolithic stack operating on a single large single-purpose computer.

Application performance is predictable due to resource separation.

High efficiency and density in resource usage.

Why do you need Kubernetes and what can it accomplish?

Containers are an excellent method to package and run your programmes. You must manage the containers that execute the apps in a production environment to guarantee that there is no downtime. For example, if one container fails, another must be started. Wouldn't it be better if a system managed this behaviour? That is where Kubernetes comes in! It provides a framework for running distributed systems in a resilient manner. It handles scaling and failover for your application, as well as providing deployment patterns and other features. Kubernetes, for example, can effortlessly manage a canary deployment for your system.

Kubernetes has the following features:

• Load balancing and service discovery Kubernetes may expose a container by utilising its DNS name or its own IP address. If there is a lot of traffic to a container, Kubernetes may load balance and spread the network traffic to keep the deployment stable.
• Storage management Kubernetes allows you to automatically mount your preferred storage system, such as local storage, public cloud providers, and others.
• Rollouts and rollbacks that are automated Kubernetes allows you to specify the ideal state for your deployed containers, and it may transform the actual state to the desired state at a regulated rate. For example, you may use Kubernetes to automate the creation of new containers for your deployment, the removal of current containers, and the adoption of all their resources to the new container.
• Bin packing that is automated You provide Kubernetes a node cluster that it may utilise to perform containerized jobs. You specify how much CPU and memory (RAM) each container requires. Kubernetes can fit containers onto your nodes to maximise resource use.
• Self-healing Kubernetes restarts failing containers, replaces them, destroys containers that do not answer to your user-defined health check, and does not advertise them to clients until they are ready to serve.
• Management of secrets and configurations Kubernetes allows you to store and handle sensitive data like passwords, OAuth tokens, and SSH keys. Secrets and application configuration may be deployed and updated without rebuilding your container images or exposing secrets in your stack configuration.

What Kubernetes does not do

Kubernetes is not your typical all-in-one PaaS (Platform as a Service) technology. Because Kubernetes works at the container level rather than the hardware level, it includes several functionality that are common to PaaS providers, such as deployment, scaling, and load balancing, and it allows customers to connect existing logging, monitoring, and alerting systems. However, Kubernetes is not a one-size-fits-all solution, and many default solutions are optional and pluggable. Kubernetes provides the building blocks for developing developer platforms while preserving user choice and freedom when possible.

Kubernetes shortcomings:

• Does not restrict the sorts of apps that can be run. Kubernetes is designed to serve a wide range of workloads, including stateless, stateful, and data-processing applications. If an application can operate in a container, it should perform admirably on Kubernetes.
• It does not deploy source code or create your application. Organizational cultures and preferences, as well as technological needs, influence Continuous Integration, Delivery, and Deployment (CI/CD) workflows.
• As built-in services, it does not include middleware (for example, message buses), data-processing frameworks (for example, Spark), databases (for example, MySQL), caches, or cluster storage systems (for example, Ceph). Such components can operate on Kubernetes and/or be accessible by Kubernetes-running apps using portable interfaces such as the Open Service Broker.
• It makes no recommendations for logging, monitoring, or alerting systems. It includes various proof-of-concept integrations as well as capabilities for collecting and exporting metrics.
• It neither provides nor requires a configuration language/system (for example, Jsonnet). It offers a declarative API that may be targeted by any type of declarative specification.
• No comprehensive machine configuration, maintenance, administration, or self-healing solutions are provided or adopted

In order to be able to fully utilise Kubernetes, operators will generally need basic understanding if YAML, Linux & command lines, as well as be able to:

• Understand the fundamentals of containers.
• Create containerized apps and deploy them on Kubernetes.
• Understand the benefits of deploying Helm charts with Kubernetes
• Understand the fundamentals of networking for Kubernetes-based applications.
• Get logs and debug your Kubernetes applications.
• Install an Istio service mesh after downloading it.
• Put security first when updating your applications

Kubernetes is more than just an orchestration system. In fact, it does away with the requirement for orchestration. Orchestration is technically described as the execution of a defined workflow: do A first, then B, then C. Kubernetes, on the other hand, is made up of a collection of autonomous, composable control processes that continually move the current state towards the supplied intended state. It shouldn't matter how you travel from point A to point B. Centralized control is also unnecessary. As a result, the system becomes more powerful, robust, resilient, and extendable.