For the 2015-12-16 meeting as the Change Proposal was announced on devel-announce list on 2015-12-03.

Fedora currently ships a Docker base image, but Docker supports a layering concept. There are some applications like Cockpit which we would like to ship as layered applications.[[BR]]
This change will deploy the build service to support building and delivering a set of layered Docker images, and will enable Fedora contributors to create and maintain Dockerfiles from which those images will be generated.
[https://fedoraproject.org/wiki/Changes/Layered_Docker_Image_Build_Service Change proposal]
[https://lists.fedoraproject.org/archives/list/devel-announce%40lists.fedoraproject.org/thread/5IP2VR5CYKLOEEM77BLEC6RNCP7L5EEH/ devel-announce announcement]