Define ci entry accessor instead of method_missing

lib/gitlab/ci/config/node/configurable.rb

@@ -55,6 +55,12 @@ module Gitlab
                        { class: entry_class,
                          description: metadata[:description] } }
 
+              define_method(symbol) do
+                raise Entry::InvalidError unless valid?
+
+                @nodes[symbol].try(:value)
+              end
+
               (@allowed_nodes ||= {}).merge!(node)
             end
           end

lib/gitlab/ci/config/node/entry.rb

@@ -52,13 +52,6 @@ module Gitlab
             {}
           end
 
-          def method_missing(name, *args)
-            super unless allowed_nodes.has_key?(name)
-            raise InvalidError unless valid?
-
-            @nodes[name].try(:value)
-          end
-
           def add_node(key, entry)
             raise NotImplementedError
           end