supported_platform.rb

class Chef
  class Recipe
    def skip_unsupported_platform
      unless supported_platform?
        Chef::Log.info("Unsupported platform #{node[:platform]} in #{cookbook_name}::#{recipe_name}, skipping recipe")
        Chef::Log.debug("You said to skip unsupported platforms in #{cookbook_name}::#{recipe_name}")
        Chef::Log.debug("and #{node['platform']} is unsupported by cookbook #{cookbook_name}. Update the cookbook's metadata")
        Chef::Log.debug("if this is a supported platform, or remove #{cookbook_name}::#{recipe_name} from the node.")
      end
    end

    def supported_platform?
      run_context.cookbook_collection[cookbook_name].metadata.platforms.include?(node['platform'])
    end
  end
end

test_recipe.rb

# Put this at the top of a recipe if you want to enforce that it should only be run on
# platforms that are supported per the cookbook's metadata

return if skip_unsupported_platform

Hat tip to Alex Howells and Jay Feldblum for the run_context.cookbook_collection reminder for inspecting cookbook metadata.