Container Super-structure

Multiple orchestration platforms support some kind of container super-structure.

(i.e., a construct or abstraction bigger than a single container.)
For instance, on Kubernetes, this super-structure is called a pod.
A pod is a group of containers (it could be a single container, too).
These containers run together, on the same host.

(A pod cannot straddle multiple hosts.)
All the containers in a pod have the same IP address.
How does that map to the Docker world?

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Anatomy of a Pod

The containers inside a pod share the same network namespace.

(Just like when using docker run --net=container:<container_id> with the CLI.)
As a result, they can communicate together over localhost.
In addition to "our" containers, the pod has a special container, the sandbox.
That container uses a special image: k8s.gcr.io/pause.

(This is visible when listing containers running on a Kubernetes node.)
Containers within a pod have independent filesystems.
They can share directories by using a mechanism called volumes.

(Which is similar to the concept of volumes in Docker.)