Chapter 1: Kubernetes Architecture

Traditional applications, such as web applications, are known to follow a modular architecture, splitting code into an application layer, business logic, a storage layer, and a communication layer. Despite the modular architecture, the components are packaged and deployed as a monolith. A monolith application, despite being easy to develop, test, and deploy, is hard to maintain and scale. This led to the growth of microservices architecture. Development of container runtimes like Docker and Linux Containers (LXC) has eased deployment and maintenance of applications as microservices.

Microservices architecture splits application deployment into small and interconnected entities. The increasing popularity of microservices architecture has led to the growth of orchestration platforms such as Apache Swarm, Mesos, and Kubernetes. Container orchestration platforms help manage containers in large and dynamic environments.

Kubernetes is an open source orchestration platform for containerized applications that support automated deployment, scaling, and management. It was originally developed by Google in 2014 and it is now maintained by the Cloud Native Computing Foundation (CNCF). Kubernetes is the first CNCF-graduated project that graduated in 2018. Established global organizations, such as Uber, Bloomberg, Blackrock, BlaBlaCar, The New York Times, Lyft, eBay, Buffer, Ancestry, GolfNow, Goldman Sachs, and many others, use Kubernetes in production at a massive scale (https://kubernetes.io/case-studies/). Large cloud providers, such as Elastic Kubernetes Service (Amazon), Azure Kubernetes Service (Microsoft), Google Kubernetes Engine (Google), and Alibaba Cloud Kubernetes (Alibaba), offer their own managed Kubernetes services.

In a microservices model, application developers ensure that the applications work correctly in containerized environments. They write a Docker file to bundle their applications. DevOps and infrastructure engineers interact with the Kubernetes cluster directly. They ensure that the application bundles provided by developers run smoothly within the cluster. They monitor the nodes, pods, and other Kubernetes components to ensure the cluster is healthy. However, security requires the joint effort of both parties and the security team. To learn how to secure a Kubernetes cluster, we will first have to understand what Kubernetes is and how it works.

In this chapter, we will cover the following topics:

• The rise of Docker and the trend of microservices
• Kubernetes components
• Kubernetes objects
• Kubernetes variations
• Kubernetes and cloud providers