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...

A talk I gave at LISA2015. A gentle introduction to Puppet for the complete beginner. This talk assumes no knowledge of Puppet and is intended for the complete beginner. Slides available here. Support files are available here.

My puppet book was released July 25th on Packtpub.com

You can also grab a copy from Amazon.

About the book

Talk I gave at Puppetcamp Seattle 2015 - June 4, 2015
Slides are here: https://goo.gl/68yr6S

Beginner talk on how to get your code onto your masters.

Tutorial from Cascadia 2015, all about automating your puppet workflow using git, git-hooks, puppet-sync and r10k.

Slides are available here:
http://goo.gl/V6BcCi

Tutorial Questions here:
http://goo.gl/du4Hqi

Files used on github:
https://github.com/uphillian/cascadia2015