This article is based on an earlier article written in Finnish.

Here I describe how to make changes to an XML file with Augeas - a useful approach when managing the whole file as a template is out of the question. The configuration file used as an example, web.xml, belong to Pwm, and we intend to set the webapp context parameter.

As discussed before it is important to get an idea of how Augeas sees the file before attempting to modify it with Puppet. First we tell which Augeas lens to use (here: Xml) and which file(s) to associate with the Xml lens. This can be done with in one step:

This translated from the original Finnish article that is available here.

The Augeas resource in Puppet allows one to manage parts of a complex configuration file instead of managing the whole file using a template or a static file. For trivial cases stdlib’s file_line resource may be sufficient. While use of templates or static files is in general more reliable and easier than use of Augeas, the latter is quite useful in many cases. As using Puppet Augeas resource directly is quite challenging, a useful practice is to first make the changes manually with “augtool” and only then convert the results into Puppet Augeas resources. We use PostgreSQL’s pg_hba.conf file here as an example.