This is a rather simple Docker image that extends the base Ubuntu (latest / Xenial 16.04) with an installation of Puppet 4 (the puppet-agent) package. This distribution is being used for some local testing with Puppet - DO NOT use this particular image in a production environment. (i.e. it's not being updated regularly.)
This image contains a rather dumb hack to keep it running - the CMD is 'tail -f /dev/null'. Kinda hacky, but it works.