Container images and containers are similar to classes and objects in the object-oriented world. Container images are the blueprint from which containers are instantiated. But these containers do not run in isolation; they run in other abstractions such as Pods, which provide unique runtime capabilities.

The patterns in this category are focused on structuring and organizing containers in a Pod to satisfy different use cases. The forces that affect containers in Pods result in the patterns discussed in the following chapters:

• Chapter 14, Init Container, introduces a separate lifecycle for initialization-related tasks and the main application containers.

• Chapter 15, Sidecar, describes how to extend and enhance the functionality of a pre-existing container without changing it.

• Chapter 16, Adapter, takes an heterogeneous system and makes it conform to a consistent unified interface that can be consumed by the outside world.

• Chapter 17, Ambassador, describes a proxy that decouples access to external services.