Right now docker build of bigtop/puppet images simply use FROM to use the vendor linux distro.
This has the affect that only one image will be downloaded and never updated. When the vendor does updates to the image, this will not be reflected by our build system.
I caught this because we have troubles with the reliability of httpredir.debian.org as the default repository. Recent debian images use deb.debian.org which is apparently backed by a commercial CDN.
So I propose to use docker build --pull=true for building bigtop/puppet images.