Architecting the Future with Abstractions and Metadata

Kubernetes has taken full advantage of this new model of flexible abstractions. It was originally built on top of Docker, but it has now abstracted away the compute unit so that even virtual machines can be used as the instance container (though this is highly experimental). Kubernetes was created by Google as an open source project based on its internal cluster management system called Borg.

Kubernetes has similar abstractions to Docker, such as volumes, services, and secrets; however, Kubernetes also has an abstraction called a pod. A pod is a grouping of containers that should be colocated and share storage and network. It is the smallest deployable unit in Kubernetes, whereas a container is the smallest deployable unit in Docker.

Kubernetes also leverages a plugin system that offers an abstraction for network and storage in addition to compute. The network system then uses a Network Policy to describe connections based on metadata. Each object in Kubernetes can have labels attached. These labels are used to not only describe an object, but also to select that object and all objects with matching labels from among the unwashed masses. A Network Policy uses these labels to apply policies to objects with matching labels.