My book is on sale right now.
Puppet, Foreman, Facter, Mcollective
Augeas is a great tool for changing only parts of a configuration file. It has a few problems though, it's slow and hard to learn and does lack some documentation. That said, unless you can use file_line or inifile, Augeas is the only game in town. The alternative is an exec with sed or awk or something terrible...