1 files changed, 81 insertions, 0 deletions
diff --git a/lib/gitlab/config/entry/configurable.rb b/lib/gitlab/config/entry/configurable.rb
new file mode 100644
index 00000000000..afdb60b2cd5
--- /dev/null
+++ b/lib/gitlab/config/entry/configurable.rb
@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Config
+    module Entry
+      ##
+      # This mixin is responsible for adding DSL, which purpose is to
+      # simplifly process of adding child nodes.
+      #
+      # This can be used only if parent node is a configuration entry that
+      # holds a hash as a configuration value, for example:
+      #
+      # job:
+      #   script: ...
+      #   artifacts: ...
+      #
+      module Configurable
+        extend ActiveSupport::Concern
+
+        included do
+          include Validatable
+
+          validations do
+            validates :config, type: Hash
+          end
+        end
+
+        # rubocop: disable CodeReuse/ActiveRecord
+        def compose!(deps = nil)
+          return unless valid?
+
+          self.class.nodes.each do |key, factory|
+            factory
+              .value(config[key])
+              .with(key: key, parent: self)
+
+            entries[key] = factory.create!
+          end
+
+          yield if block_given?
+
+          entries.each_value do |entry|
+            entry.compose!(deps)
+          end
+        end
+        # rubocop: enable CodeReuse/ActiveRecord
+
+        class_methods do
+          def nodes
+            Hash[(@nodes || {}).map { |key, factory| [key, factory.dup] }]
+          end
+
+          private
+
+          # rubocop: disable CodeReuse/ActiveRecord
+          def entry(key, entry, metadata)
+            factory = ::Gitlab::Config::Entry::Factory.new(entry)
+              .with(description: metadata[:description])
+
+            (@nodes ||= {}).merge!(key.to_sym => factory)
+          end
+          # rubocop: enable CodeReuse/ActiveRecord
+
+          def helpers(*nodes)
+            nodes.each do |symbol|
+              define_method("#{symbol}_defined?") do
+                entries[symbol]&.specified?
+              end
+
+              define_method("#{symbol}_value") do
+                return unless entries[symbol] && entries[symbol].valid?
+
+                entries[symbol].value
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end