This is a Docker container with asterisk running on Ubuntu. You can check out the Dockerfile, everything is done in one RUN command to keep the image size to the minimum.
The source tgz is downloaded (instead of added to the image) so that it's never persisted on a layer.
If /etc/asterisk is mounted to a volume with files, the image won't do anything. If it's mounted to an empty folder, it will populate it with the default files (the ones generated by the make samples command).
Is it quick to build? is it easy to reuse the layers? hell no... but you can easily tweak the Dockerfile so that you generate the intermediate images... my goal was to do it as small as possible (withi this approach, neither wget or the asterisk source are taking space in any layer).
This was based on this docker image from dougbtv, so kudos and thanks!
Note: I've disabled the modules I'm not using... run menuselect/menuselect --help to check out the different options that are available (yes, it does require you to fiddle with the Dockerfile :P)