I would use something like reprepro on your master to set-up the apt repository for ganglia, then use the puppetlabs-apt module to add the apt-repo on your master to all your agents.
There's a reprepro module on the forge that you can probably use to set that up.
So, if your master is called puppet-master.example.com
, and you set it up as an apt server, you could add some code like this to all your agents:
apt::source { 'ganglia-mirror':
location => 'http://puppet-master.example.com/aptserver',
release => 'dist',
repos => 'ganglia',
include_src => false,
}
I'd recommend reading through the documentation on both modules, and you should be able to achieve a Ganglia APT mirror on your Puppet master.