1 files changed, 33 insertions, 0 deletions
diff --git a/lib/gitlab/ci/config/interpolation/inputs/string_input.rb b/lib/gitlab/ci/config/interpolation/inputs/string_input.rb
new file mode 100644
index 00000000000..39870582d0c
--- /dev/null
+++ b/lib/gitlab/ci/config/interpolation/inputs/string_input.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    class Config
+      module Interpolation
+        class Inputs
+          class StringInput < BaseInput
+            def self.matches?(spec)
+              # The input spec can be `nil` when using a minimal specification
+              # and also when `type` is not specified.
+              #
+              # ```yaml
+              # spec:
+              #   inputs:
+              #     foo:
+              # ```
+              spec.nil? || (spec.is_a?(Hash) && [nil, type_name].include?(spec[:type]))
+            end
+
+            def self.type_name
+              'string'
+            end
+
+            def valid_value?(value)
+              value.nil? || value.is_a?(String)
+            end
+          end
+        end
+      end
+    end
+  end
+end