Kubernetes: Up and Running, 2nd Edition

Chapter 18. Organizing Your Application

Throughout this book we have described various components of an application built on top of Kubernetes. We have described how to wrap programs up as containers, place those containers in Pods, replicate those Pods with ReplicaSets, and roll out software each week with deployments. We have even described how to deploy stateful and real-world applications that put together a collection of these objects into a single distributed system. But we have not covered how to actually work with such an application in a practical way. How can you lay out, share, manage, and update the various configurations that make up your application? That is the topic for this chapter.

Principles to Guide Us

Before digging into the concrete details of how to structure your application, it’s worth considering the goals that drive this structure. Obviously, reliability and agility are the general goals of developing a cloud-native application in Kubernetes, but moving to the next level of detail, how does this actually relate to how you design the maintenance and deployment of your application? The following sections describe the various principles that we can use as a guide to design a structure that best suits these goals. The principles are:

• Filesystems as the source of truth

• Code review to ensure the quality of changes

• Feature flags for staged roll forward and roll back

Filesystems as the Source of Truth

When you first begin to explore Kubernetes, as ...