A big part of Chef’s resources internal nuts and bolts has been change over the last year. One of the most welcome changes has been recipe_eval - a mini Chef run that can be used inside Chef LWRP. This mechanism has been put to good use in use_inline_resources dsl directive in LWRP, in chef-stage and in inline_recipe.
Now that LWRPs have become so powerful, there aren’t many reasons to use definitions. The most common reason people use definitions and not LWRP is the absence of include_recipe - which now is available in LRWPs. Lets explore this:
action :send do
begin
require 'aws'
rescue LoadError
recipe_eval do
run_context.include_recipe "xml::ruby"
chef_gem "aws-sdk"
end
require 'aws'
end
converge_by(block_name) do
# Actually sending by SNS now that we have the aws-sdk gem
As you can see, the trick is to use run_context.include_recipe instead of just include_recipe since it isn’t directly available in recipe_eval (alternatively one could include Chef::DSL::InclueRecipe mixin).