It's an easy way to capture network traffic data between Kubernetes/OpenShift pods, allowing developers to better analyze and debug communication problems in containerized applications and to solve issues quicker and more effectively.

In Kubernetes, a pod is a group of one or more containers with shared storage and network. A sidecar is a utility container in a pod that's loosely coupled to the main application container. ... Soon it became clear that Kubernetes should formally identify sidecars, and handle the lifecycle of such containers differently.