Review: Red Hat does Docker the hard way


Red Hat’s Project Atomic is an opinionated way to run Linux containers. The Atomic Host operating system comes with Docker (containers), Flannel (networking), OSTree (host management), Etcd (distributed key-value store), and Kubernetes (orchestration) already installed. 

Kubernetes is one of the two popular container orchestration systems, the other being Docker Swarm. You could call it “full-strength,” but with that comes additional complexity and administrative overhead.

Kubernetes coordinates the creation of “pods” across multiple Atomic hosts. Pods are groups of Docker containers that logically separate services in an application. The containers in a pod share an IP address and communicate over localhost.

Flannel provides an overlay network for Atomic hosts, allowing every pod in the cluster to communicate with any other pod or service within the cluster. This overlay network is used for container networking only. A Kubernetes proxy service provides access to the host IP space.