Kubernetes for Beginners: An Indepth Introduction

Introduction

Kubernetes, often abbreviated as K8s, is an open-source platform that automates Linux container operations. It eliminates many of the manual processes involved in deploying and scaling containerised applications. In other words, you can cluster together groups of hosts running Linux containers, and Kubernetes helps you easily and efficiently manage those clusters.

Why Use Kubernetes?

Containers are a good way to bundle and run your applications. In a production environment, you need to manage the containers that run the applications and ensure that there is no downtime. For example, if a container goes down, another container needs to start. Wouldn’t it be easier if this behaviour was handled by a system? That’s how Kubernetes comes to the rescue!

Kubernetes provides you with:

• Fault tolerance: If one or more of your application instances crash or become unresponsive, K8s can automatically replace them with healthy instances.
• Service discovery and load balancing: With DNS name or their own IP address for containers, services inside your cluster can reach each other without knowing where they’re running.
• Automated rollouts and rollbacks: You can describe the desired state for your deployed containers using K8s, and it can change the actual state to the desired state at a controlled rate.

The Architecture of Kubernetes

A Kubernetes setup is typically divided into master nodes (control plane) and worker nodes. The master node is responsible for maintaining the desired state of the cluster such as which applications are running or which container images they use. Worker nodes actually run these applications.

Main Components of Kubernetes Architecture:

• Master Node: The master node is responsible for managing the Kubernetes cluster. It is the entry point of all administrative tasks.
• Kube-API Server: This is the frontend of the control plane and exposes APIs to interact with Kubernetes.
• EtcD: This is a distributed and consistent key-value store used as Kubernetes’ backing store for all cluster data.
• Kube-Scheduler: This component on master takes into account individual and collective resource requirements, hardware/software/policy constraints, affinity and anti-affinity specifications, data locality, inter-workload interference and deadlines to determine where to run a pod which are part of your workload.

Kubernetes Objects

Kubernetes objects are persistent entities in the Kubernetes system. They represent the state of your cluster at any given moment. Once you’ve created an object, the Kubernetes system will continually work to ensure that object exists. By creating an object, you’re effectively telling the Kubernetes system what you want your cluster’s workload to look like; this is your cluster’s desired state.

Main Components of Kubernetes Objects:

• Pods: A Pod represents a single instance of a running process in a cluster and can contain one or more containers.
• Services: A way to expose an application running on a set of Pods as a network service. With Kubernetes you don’t need to modify your application to use an unfamiliar service discovery mechanism.
• Volumes: A Volume is essentially a directory accessible to all containers running in a pod. In contrast to Docker which allows you to create a volume on one machine, in K8s it provides much more functionality.

Conclusion

Kubernetes is a powerful open-source platform for managing containerised applications. It provides the infrastructure needed to deploy and run them at scale, along with services that make it easy to discover and communicate with those applications. While Kubernetes does have a steep learning curve, the benefits of adopting it can be significant. Whether you’re a developer looking to streamline your workflows or an operations team seeking to maximise efficiency, Kubernetes offers tools and concepts that can help you meet these goals.