Merge pull request #179 from k0kubun/autoload-plugin

Fallback to autoload resource plugin

lib/itamae/resource.rb

@@ -34,11 +34,20 @@ def get_resource_class(method)
           begin
             ::Itamae::Plugin::Resource.const_get(to_camel_case(method.to_s))
           rescue NameError
-            raise Error, "#{method} resource is missing."
+            autoload_plugin_resource(method)
           end
         end
       end
 
+      def autoload_plugin_resource(method)
+        begin
+          require "itamae/plugin/resource/#{method}"
+          ::Itamae::Plugin::Resource.const_get(to_camel_case(method.to_s))
+        rescue LoadError, NameError
+          raise Error, "#{method} resource is missing."
+        end
+      end
+
       def define_resource(name, klass)
         class_name = to_camel_case(name.to_s)
         if Resource.const_defined?(class_name)