[chef] ohai plugin development gotchas?

[Sascha Bates < >]

I've written a chunk of ruby that parses a host name and returns several key pieces of information that we want to use as attributes.  Some are new attributes and some we have been using by setting roles with one attribute on the node.  This is mostly environment-related stuff, one way or another; data center location, prod/dev/qa environment, zoning (internet facing, etc), server type (web/app/image/db), and other things.  I'd like to get away from using roles to manage this as we have hundreds of (logically-named) servers that Chef will ultimately mange and run list management is still very manual.

I was thinking to make it an ohai plugin since that sets node attributes very early on and can't be overridden.  I was wondering if anyone else has been doing much with ohai plugins and if they've run into any issues or problems that I should be aware of before I go down this path?  We're currently running .09.12 but trying to find the time to move to .10.

Thanks,
Sascha