The perfect storm – that is how the current state of the software development world can be described. The sources of this storm are as follows:

• Open source software (OSS): This provides a foundational framework that makes almost any software possible.
• Technology and architecture advancements: This enables the orchestration of loosely coupled systems that consist of micro applications leveraging microservices, micro frontends, and multiple databases.
• Public clouds: For instance, Azure, AWS, and Google Cloud – these provide scalable infrastructure for a company of any size.
• Containerization and orchestration: For instance, Docker and Kubernetes – making DevOps culture possible.

Azure Kubernetes Service (AKS) packages and manages the complexity of putting together all of the preceding sources for you. As an engineer, it is still very useful to know the underpinnings of AKS technologies. We will explore the foundations of the technologies (you might be surprised to see how really old they are) that power AKS. You will learn about processes in Linux, and how Linux is related to Docker. Even though Kubernetes is technically a container runtime-agnostic platform (you will find out what this means shortly), Docker is the de facto container technology that is used practically everywhere. You will see how various processes fit nicely into Docker, and how Docker fits nicely into Kubernetes (just like the cute Russian dolls).

This chapter is the longest chapter that you will read in terms of theory in this book. You will get your hands dirty pretty quickly in the following chapters. Step by step, you will be building applications that can scale and are secure. This chapter gives you a brief introduction to the information that you will need if you want to dig deeper, or wish to troubleshoot when something goes wrong (remember, Murphy was an optimist!). Having cursory knowledge of this chapter will demystify much of the magic as you build your Azure AD-authenticated, Let's Encrypt-protected application that scales on demand based on the metrics that you are monitoring.

The following topics will be covered in this chapter:

• The foundational technologies that enable AKS
• The fundamentals of Docker
• The fundamentals of Kubernetes