1 files changed, 46 insertions, 0 deletions
diff --git a/lib/gitlab/ci/input/arguments/required.rb b/lib/gitlab/ci/input/arguments/required.rb
new file mode 100644
index 00000000000..b4e218ed29e
--- /dev/null
+++ b/lib/gitlab/ci/input/arguments/required.rb
@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Input
+      module Arguments
+        ##
+        # Input::Arguments::Required class represents user-provided required input argument.
+        #
+        class Required < Input::Arguments::Base
+          ##
+          # The value has to be defined, but it may be empty.
+          #
+          def validate!
+            error('required value has not been provided') if value.nil?
+          end
+
+          def to_value
+            value
+          end
+
+          ##
+          # Required arguments do not have nested configuration. It has to be defined a null value.
+          #
+          # ```yaml
+          #   spec:
+          #     inputs:
+          #       website:
+          # ```
+          #
+          # An empty value, that has no specification is also considered as a "required" input, however we should
+          # never see that being used, because it will be rejected by Ci::Config::Header validation.
+          #
+          # ```yaml
+          #   spec:
+          #     inputs:
+          #       website: ""
+          # ```
+          def self.matches?(spec)
+            spec.to_s.empty?
+          end
+        end
+      end
+    end
+  end
+end