Kubernetes – The Basics

Kubernetes is easily one of the most fun words to say in IT. It sounds like it's straight out of a sci-fi movie, doesn't it? But don't be fooled by its quirky name. Kubernetes is a powerhouse in the world of container orchestration.

Kubernetes has its roots in Google, inspired by a system called Borg. You might think the name Kubernetes came from the same sci-fi source, but it actually means 'helmsman' in Greek. (Enjoy saying Kubernetes, but tired of typing it? It’s often referred to as K8s, with the 8 representing the 8 letters between ‘K’ and ‘s’.)

Today, K8s is widely adopted across the industry, and for good reason.

One of the main reasons for Kubernetes' popularity is its ability to efficiently manage containers, and scale and contract quickly. It’s transformed the way we manage and deploy applications, making it simpler and more efficient.

If you're new to the world of Kubernetes and all this talk about containers, let's break it down.

Virtual Machines (VMs) are full operating systems that sit at the hardware level, and containers live at the operating system level. 

Think of your environment as a bustling neighborhood, populated with individual houses (VMs) and apartments in a block (containers).

In our analogy, VMs are the houses. Similar to how you furnish a house and tailor it to your needs, VMs demand time and effort to set up. Extending the housing comparison, VMs need their very own 'utility' connections and own 'property'. They are resource-intensive as they come packed with services, applications, configurations, and more.

Containers, on the other hand, are like the apartments in a building. They are lean and equipped with only the essential components required to run an application. They share resources with other apartments (containers), yet function independently. Because of their lightweight nature, they are far more portable and easier to manage than building an entire house.

Containers can be much more efficient at scale than virtual machines. They're lighter, quicker, and can be replicated at scale. Because we only specify the services needed at runtime, they generally consume less resources than VMs. 

And Kubernetes? It's like the super-efficient property manager of an apartment building. It sets up these apartments (containers) swiftly, manages the resources, scales them, and can even manage the standalone homes (VMs), too. 

Its skill lies in managing hundreds, or even thousands, of containers at scale, providing self-healing capabilities to ensure your workloads are always running smoothly.

Let's break down some of the key concepts in Kubernetes.

Pods are the basic units of deployment, representing the smallest and simplest units in the object model that you can create or deploy.

A Pod encapsulates an application container (or, in some cases, multiple containers), storage resources, a unique network IP, and options that govern how the container(s) should run.

This is where containers get deployed – the worker node. Worker nodes can be physical or virtual machines, and they house one or more pods.

This is a group of nodes managed by a master node. K8s clusters are where all the magic happens. The Kubernetes master node coordinates everything, maintains a shared state for the entire cluster, and schedules workloads to different nodes.

The Kubernetes Object is a fundamental element representing the state of your Kubernetes cluster, including applications running, the nodes they're operating on, allocated resources, and associated policies. It offers a structured interface through the Kubernetes API, simplifying interactions with applications and their settings.

This ensures that a desired number of pod replicas are always running. If any pods fail, the ReplicaSet creates new ones automatically. It's like having a second apartment that's identical to the first. If something happens, you can go to your backup apartment, without changing anything.

The deployment resource is responsible for managing the rollout and scaling of your application containers. It defines how many replicas of an application should be running at a given time, and allows for easy updates and rollbacks.

Services expose pods to other services within or outside the cluster. They allow for communication between different components in the Kubernetes architecture.

Think of this as a package manager for Kubernetes applications. It allows you to easily install, upgrade, and manage applications on your cluster. For more information on Kubernetes Helm, see our blog here. 

The Kubernetes Control Plane is often described as the brain of the Kubernetes system, responsible for maintaining the cluster's desired state. It’s comprised of various components, each serving a specific purpose. 

The API Server acts as the front end of the control plane, fielding requests and processing REST operations. The etcd is a consistent and highly available data store used by Kubernetes to keep all its cluster data safe. 

The Scheduler is responsible for placing Pods onto Nodes based on the workload requirements and resources. 

Lastly, the Controller Manager oversees the different controllers that regulate the state of the cluster, manage the lifecycle of various objects within Kubernetes, and perform routine tasks.

These components work together to ensure seamless operation, coordination, and management of your Kubernetes cluster. They keep track of all Kubernetes objects and ensure the current state of the system matches the desired state specified by users. It's like having a super-efficient apartment manager, always making sure that everything in the building is operating smoothly.

To help you in your quest of becoming a Helmsman in the world of Kubernetes, here's a quick dictionary of common abbreviations used in the ecosystem:

• K8s: Short form of Kubernetes

• K3s: Lightweight Kubernetes distribution

• Helm: Package manager for Kubernetes applications

• etcd: Distributed key-value store used by Kubernetes

• API server, controller-manager, scheduler: Key components of the Kubernetes control plane

Kubernetes thrives in software stacks that need to scale quickly. It can dynamically adjust to the requirements of your application, ensuring that it can smoothly handle sudden bursts of users or data by scaling pods or nodes. For example, in the event of a large influx of users, or a sudden increase in data traffic, Kubernetes deployments shine with its auto-scaling feature where you define a desired state.

It can efficiently spin up new pods to handle the increased load and distribute it evenly across all available resources (nodes). This ensures that your application stays responsive and that user experience remains consistent, no matter how heavy the load. It's like having a property manager who can swiftly arrange for additional apartments when there's a sudden surge of potential tenants.

Likewise, when data traffic subsides, Kubernetes can just as efficiently scale down resources, ensuring optimal resource utilization and cost efficiency. It can decommission the extra pods or nodes–depending on where your cluster is deployed and how it’s configured–it had spun up, ensuring you're not using (or paying for!) more resources than you need.

Kubernetes can help your application gracefully handle the ebb and flow of traffic, ensuring smooth sailing even in the choppiest of seas. It's the helmsman that navigates your application through the waves of user demand, ensuring that it always reaches its destination.

While Docker and Kubernetes serve different purposes, they are often mentioned together as they both play significant roles in managing containers. 

Docker, a platform for containerization, is used to package an application along with its runtime environment into a container. Kubernetes, on the other hand, is a container orchestration tool that manages these containers across multiple machines.

A person would use Kubernetes instead of Docker when they need to manage a large number of containers across multiple machines. For instance, if you have an application that needs to scale quickly to maintain user experience or if you need to manage different environments for development, testing, and production, Kubernetes is an excellent choice. It offers auto-scaling, which allows for the dynamic adjustment of resources based on workload, and it also provides a robust system for managing service discovery, which is critical when dealing with multiple containers.

Additionally, Kubernetes shines in complex, multi-cloud, or hybrid-cloud environments. It allows for a consistent user experience across different infrastructures, managing the deployment and scaling of applications no matter where they are hosted.

So, while Docker is ideal for creating and managing individual containers, when your application grows and begins to require complex management and coordination of multiple containers across different servers or environments, that's where Kubernetes comes in.

Keeping your Kubernetes clusters up-to-date is crucial.

Updates often include important security patches. Hackers are always on the lookout for vulnerabilities to exploit, and out-of-date software can leave your system exposed to an attack. This is akin to leaving your apartment's front door unlocked.

Updating Kubernetes regularly also ensures you have access to the latest features and improvements. Also, it helps to avoid the potential problems and compatibility issues that could occur with other software or systems you're using. This can help boost the performance of your applications and make your systems more efficient and reliable. 

Kubernetes follows an N-2 support policy, which means that the Kubernetes project maintains bug fixes and security patches for the most recent three minor releases; e.g. 1.28, 1.27, and 1.26 at the time of writing. 

An N-2 support policy is a common practice in software development where the developers commit to maintaining, fixing bugs, and providing security patches for the most recent three versions of the software. The 'N' represents the latest version, while 'N-2' indicates two versions before the current one. For instance, if the latest Kubernetes version is 1.28 (N), the developers will still support versions 1.27 (N-1) and 1.26 (N-2). 

This policy allows users some flexibility in updating their systems, knowing they can still receive necessary bug fixes and security updates even if they aren't using the absolute latest version. It is, however, recommended to keep systems as up-to-date as feasible to benefit from the latest features and improvements.

Remember, keeping your Kubernetes system updated isn't just about installing the latest features, it's about keeping your system secure and running at its optimal performance. It’s important to dedicate the time and resources to keep Kubernetes up to date because upgrades and updates can be quite involved. Employing the use of endpoint management software can make this task less daunting

Kubernetes is a robust tool. It rescues teams from the chaos of managing containerized applications at scale. But where does it really shine?

When you have an application that's becoming popular, Kubernetes is your go-to friend. It can manage high-traffic loads by balancing them across multiple instances of your application. It's like when you have a housewarming party and use all rooms to accommodate guests instead of cramming everyone into the living room. Now, picture you can push a button, and add more rooms to your house. 

Kubernetes can facilitate quick and reliable deployment of new versions of your application, ensuring your users always have access to the latest and greatest features you've developed.

Kubernetes makes managing microservices a lot easier. It helps you to deploy, scale, and manage the many moving parts of a microservices architecture. Think of each service as a room in your apartment complex, and Kubernetes as the property manager ensuring every room is in tip-top shape.

Kubernetes isn't picky about where it operates. Whether you're running applications on-premises, in the public cloud, or a mix of both, Kubernetes has got you covered. Its support for distributed systems makes Kubernetes easily scalable across hybrid environments.

Kubernetes is the superstar when it comes to ensuring zero downtime for your applications. It supports rolling updates, which means that it can update your application piece by piece, without having to take it entirely offline. It's this feature of Kubernetes that keeps your applications up and running, even when updates are rolling out so that your users never have to face any interruptions.

Think of Kubernetes like a top-tier sports car. It's not made for leisurely drives to the grocery store or the occasional trip to the countryside. It's built for speed, agility, and handling the twists and turns of a race track. In the same way, Kubernetes shines when it's paired with applications that are designed to be scalable right from the start. If you're trying to run monolithic applications—that were not designed with scalability in mind—on Kubernetes, you might not see the benefits you're hoping for.

And if all you need is a commuter car, you might not need the high-octane power of Kubernetes. It's like buying a sports car to drive to work. Sure, you'll turn a few heads (and maybe have some fun), but your needs could be perfectly met by a more economical, easy-to-handle vehicle. Similarly, if your project is small and lacks complexity, simpler solutions like Docker Swarm or even basic containerization might serve you just fine. 

Remember—it's not about having the fastest car on the block, it's about having the right tool for the job.