Fog.credentials Support

Switching the 'rackspace_api_username' key name would cause all existing knife.rb files with to be invalid. This less common case can be solved using something like this:

require 'fog'

knife[:rackspace_api_username] = Fog.credentials[:rackspace_username] || "#{ENV['RACKSPACE_USERNAME']}"
knife[:rackspace_api_key] = Fog.credentials[:rackspace_api_key] || "#{ENV['RACKSPACE_API_KEY']}"

It should be easy to fix:

connection = Fog::Compute.new(
:provider => 'Rackspace',
:rackspace_api_key => Chef::Config[:knife][:rackspace_api_key],
:rackspace_username => Chef::Config[:knife][:rackspace_api_username] || Chef::Config[:knife][:rackspace_username],
:rackspace_auth_url => Chef::Config[:knife][:rackspace_api_auth_url] || config[:rackspace_api_auth_url]
)

wherever connections are created.

Then all existing knife.rb files remain valid, and we can:

require 'fog'
knife.merge! Fog.credentials

This has been fixed/merged:
https://github.com/opscode/knife-rackspace/commit/4e5dcc2356460ccc65a221df93b682225b1f1975

This has been released.