Intelligent Provider Action

library.rb

module ChefExt
  module RecipeEval

    protected

    def recipe_eval

      sub_run_context = @run_context.dup
      sub_run_context.resource_collection = Chef::ResourceCollection.new

      begin
        original_run_context, @run_context = @run_context, sub_run_context
        yield
      ensure
        @run_context = original_run_context
      end

      begin
        Chef::Runner.new(sub_run_context).converge
      ensure
        if sub_run_context.resource_collection.any?(&:updated?)
          new_resource.updated_by_last_action(true)
        end
      end

    end

  end
end

provider.rb

action :do_something do

  # So that we can refer to these within the sub-run-context block.
  cached_new_resource = new_resource
  cached_current_resource = current_resource

  # Setup a sub-run-context.
  sub_run_context = @run_context.dup
  sub_run_context.resource_collection = Chef::ResourceCollection.new

  # Declare sub-resources within the sub-run-context. Since they are declared here,
  # they do not pollute the parent run-context.
  begin
    original_run_context, @run_context = @run_context, sub_run_context
    file cached_new_resource.path
    execute cached_new_resource.command do
      not_if { ::File.exist?(cached_new_resource.other_path) }
    end
  ensure
    # Restore the original run-context inherited from the calling recipe.
    @run_context = original_run_context
  end

  # Converge the sub-run-context inside the provider action.
  # Make sure to mark the resource as updated-by-last-action if any sub-run-context
  # resources were updated (any actual actions taken against the system) during the
  # sub-run-context convergence.
  begin
    Chef::Runner.new(sub_run_context).converge
  ensure
    if sub_run_context.resource_collection.any?(&:updated?)
      new_resource.updated_by_last_action(true)
    end
  end

end

provider2.rb

# Override the existing Chef::Provider#recipe_eval, which is less complete.
# This time without comments.
def recipe_eval

  sub_run_context = @run_context.dup
  sub_run_context.resource_collection = Chef::ResourceCollection.new

  begin
    original_run_context, @run_context = @run_context, sub_run_context
    yield
  ensure
    @run_context = original_run_context
  end

  begin
    Chef::Runner.new(sub_run_context).converge
  ensure
    if sub_run_context.resource_collection.any?(&:updated?)
      new_resource.updated_by_last_action(true)
    end
  end

end

# Use it
action :do_something do
  recipe_eval do

    file "/etc/my-package.conf" do
      owner new_resource.user
      group new_resource.group
      mode new_resource.mode
      action :create
    end

  end
end

provider3.rb

include ChefExt::RecipeEval

# Use it
action :do_something do
  recipe_eval do

    file "/etc/my-package.conf" do
      owner new_resource.user
      group new_resource.group
      mode new_resource.mode
      action :create
    end

  end
end