[chef] Ohai is missing sigar?

[Vladimir Girnet < >]

Hi Gents,

Chef-omnibus 10.14.4, with Ohai 6.14.0, on CentOS 6.3 on Rackspace 

I've started 4 servers, and today I've noticed that I'm missing 
cloud/rackspace attributes on servers. 

Running "chef-client -l debug" showed this error:
----------------------
[2012-10-12T08:42:01+00:00] DEBUG: Loading plugin cloud
[2012-10-12T08:42:01+00:00] DEBUG: Loading plugin rackspace
[2012-10-12T08:42:01+00:00] DEBUG: Loading plugin ohai_time
[2012-10-12T08:42:01+00:00] DEBUG: Loading plugin network_listeners
[2012-10-12T08:42:01+00:00] DEBUG: Plugin network_listeners threw exception 
#<LoadError: cannot load such file -- sigar> 
/opt/chef/embedded/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in 
`require'
/opt/chef/embedded/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in 
`require'
/opt/chef/embedded/lib/ruby/gems/1.9.1/gems/ohai-6.14.0/lib/ohai/plugins/network_listeners.rb:19:in
 `from_file'

----------------------

Running "/opt/chef/embedded/bin/gem install sigar", and chef-client once 
again fixed the issue, cloud/rackspace attributes appeared back.
It looks like "sigar" gem is required for Ohai, but not installed by default. 

Is this expected or a bug?

--
Vladimir Girnet
Infrastructure Engineer
Tacit Knowledge
http://www.tacitknowledge.com