1 files changed, 29 insertions, 0 deletions
diff --git a/lib/gitlab/ci/external/file/base.rb b/lib/gitlab/ci/external/file/base.rb
new file mode 100644
index 00000000000..f4da07b0b02
--- /dev/null
+++ b/lib/gitlab/ci/external/file/base.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module External
+      module File
+        class Base
+          YAML_WHITELIST_EXTENSION = /(yml|yaml)$/i.freeze
+
+          def initialize(location, opts = {})
+            @location = location
+          end
+
+          def valid?
+            location.match(YAML_WHITELIST_EXTENSION) && content
+          end
+
+          def content
+            raise NotImplementedError, 'content must be implemented and return a string or nil'
+          end
+
+          def error_message
+            raise NotImplementedError, 'error_message must be implemented and return a string'
+          end
+        end
+      end
+    end
+  end
+end