The images registry is normally a single web app which is not scalable, and several gigabyte images can take a long time to be downloaded. In our cluster we're running the UBER Kraken - a peer-to-peer layer that caches images layers on cluster nodes and provides significantly improved download speed.
Currently it's set up to serve the images from the following registries:
|docker hub (hub.docker.io) official images||library|
|docker hub (hub.docker.io) user images|
If you need some other image cached, let us know in Matrix.
The way to use kraken is to specify the image as
localhost:30081/prefix/<your_image>, for example
localhost:30081/prp/jupyter:latest. For user-uploaded docker hub images use the user name as prefix. Nodes will download and cache your image, and next time the download to another node will be much faster.
There is now automatic replacement of supported image URLs to use kraken for all pods. If you want your namesapce excluded for some reason, let us know in Matrix.