[chef] Understanding node attributes set from 'role' cookbooks

[Lewis Thompson < >]

Hello,

I'm in the process of converting my roles into role cookbooks.  A
minority of these roles set attributes and these are causing me
problems.

Assuming my cookbook a has the following in an attributes file:

  default['a']['b'] = true

I can override this in a cookbook recipe as expected:

  node.default['a']['b'] = false

However, as soon as attributes files start performing logic based on
attributes things break down as demonstrated in the following example
cookbook (roleattributes):

attributes file:

  default['roleattributes']['test'] = true
  if node['roleattributes']['test'] == true
    default['roleattributes']['testistrue'] = true
  else
    default['roleattributes']['testistrue'] = false
  end

default recipe:

  node.normal['roleattributes']['test'] = false
  require 'pp'
  pp node.debug_value(:roleattributes, :test)
  pp node.debug_value(:roleattributes, :testistrue)

The output from the pp command during a Chef run is (with all
not_present stripped for clarity):

  # pp node.debug_value(:roleattributes, :test)
   ["default", true],
   ["normal", false],
  # pp node.debug_value(:roleattributes, :testistrue)
   ["default", true],

As can be seen node['roleattributes']['test'] is correctly false while
node['roleattributes']['testistrue'] is true.  By comparison when I
define roleattributes.test=false in my role normal attributes I get a
different result:

  # pp node.debug_value(:roleattributes, :test)
   ["default", true],
   ["normal", false],
  # pp node.debug_value(:roleattributes, :testistrue)
   ["default", false],

Is there any way around this somewhat unexpected (to me) behaviour?
At the moment it is holding up a full migration towards role cookbooks
(to allow versioning, etc.)

Many thanks

Lewis