Container engines like Docker and rkt download container images containing applications to be executed. With Kubernetes – a container orchestration system – updates to a new version of an application can be propagated on the nodes automatically. When the new version has only a few changes compared to the previous versions, this results in downloading the same content again, wasting network bandwidth. With casync – a content-addressable data synchronization tool – we could do better.
I’ll start by introducing the current container image distribution mechanisms used in the Docker Registry and in the App Container Image Discovery protocol. I’ll quickly mention other ideas around saving network bandwidth, like bittorrent in quay.io. Then, I'll present my experiments with casync (Content-Addressable Data Synchronization Tool) and show how much the network usage can be reduced in a Kubernetes cluster.
Speakers: Alban Crequy