How can I set up a dependency to a Ruby library which doesn't exist at the time Chef loads recipes?

Question

Scenario:

• Recipe1: downloads archives, extracts them. Makes available a CLI which also defines a Ruby library.
• Recipe2: leverages Ruby API from the aforementioned library.

In recipe1/recipes/default.rb:

.. do work
node[:recipe1][:filePath] = ".." #path to file

In recipe2/recipes/default.rb:

require node[:recipe1][:filePath]/lib/Library
.. do work

However, when loading the recipes, Chef announces:

[Wed, 17 Aug 2011 19:32:23 +0800] DEBUG: Loading cookbook apache2's definitions from /var/chef/cookbooks/apache2/definitions/web_app.rb
[Wed, 17 Aug 2011 19:32:23 +0800] DEBUG: Loading cookbook apache2's definitions from /var/chef/cookbooks/apache2/definitions/apache_module.rb
[Wed, 17 Aug 2011 19:32:23 +0800] DEBUG: Loading Recipe Recipe1 via include_recipe
[Wed, 17 Aug 2011 19:32:23 +0800] DEBUG: Found recipe default in cookbook Recipe1
[Wed, 17 Aug 2011 19:32:23 +0800] ERROR: Running exception handlers
[Wed, 17 Aug 2011 19:32:23 +0800] ERROR: Exception handlers complete
[Wed, 17 Aug 2011 19:32:23 +0800] DEBUG: Re-raising exception: LoadError - no such file to load -- /path/to/library/Library
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36:in `require'
/var/chef/cookbooks/hsltcli/recipes/default.rb:63:in `from_file'
/usr/lib64/ruby/gems/1.8/gems/chef-0.10.4/bin/../lib/chef/cookbook_version.rb:578:in `load_recipe'
/usr/lib64/ruby/gems/1.8/gems/chef-0.10.4/bin/../lib/chef/mixin/language_include_recipe.rb:40:in `include_recipe'
/usr/lib64/ruby/gems/1.8/gems/chef-0.10.4/bin/../lib/chef/mixin/language_include_recipe.rb:27:in `each'
/usr/lib64/ruby/gems/1.8/gems/chef-0.10.4/bin/../lib/chef/mixin/language_include_recipe.rb:27:in `include_recipe'

How can I declare/enable a Ruby library after all recipes are in the process of running?

Answer 1

Using a Gem package, you call the run_action() method on the resource so it happens during compile time, and make sure that the Gem paths are cleared. For example:

r = gem_package "dynect_rest" do
  action :nothing
end
r.run_action(:install)
require 'rubygems'
Gem.clear_paths

Or, slightly more compact:

gem_package "dynect_rest" do
  action :nothing
end.run_action(:install)
require 'rubygems'
Gem.clear_paths

(the require 'rubygems' is probably not strictly necessary, as it should already be loaded by Chef, but we want to be sure)