1 files changed, 44 insertions, 0 deletions
diff --git a/config/initializers/rack_multipart_patch.rb b/config/initializers/rack_multipart_patch.rb
new file mode 100644
index 00000000000..78cf6244814
--- /dev/null
+++ b/config/initializers/rack_multipart_patch.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Rack
+  module Multipart
+    class << self
+      module MultipartPatch
+        def extract_multipart(req, params = Rack::Utils.default_query_parser)
+          log_multipart_warning(req) if log_large_multipart?
+
+          super
+        end
+
+        def log_multipart_warning(req)
+          content_length = req.content_length.to_i
+
+          return unless content_length > log_threshold
+
+          message = {
+            message: "Large multipart body detected",
+            path: req.path,
+            content_length: content_length,
+            correlation_id: ::Labkit::Context.correlation_id
+          }
+
+          log_warn(message)
+        end
+
+        def log_warn(message)
+          warn message.to_json
+        end
+
+        def log_large_multipart?
+          Gitlab::Utils.to_boolean(ENV['ENABLE_RACK_MULTIPART_LOGGING'], default: true) && Gitlab.com?
+        end
+
+        def log_threshold
+          ENV.fetch('RACK_MULTIPART_LOGGING_BYTES', 100_000_000).to_i
+        end
+      end
+
+      prepend MultipartPatch
+    end
+  end
+end