1 files changed, 70 insertions, 0 deletions
diff --git a/lib/gitlab/web_hooks/rate_limiter.rb b/lib/gitlab/web_hooks/rate_limiter.rb
new file mode 100644
index 00000000000..73d59f6f786
--- /dev/null
+++ b/lib/gitlab/web_hooks/rate_limiter.rb
@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module WebHooks
+    class RateLimiter
+      include Gitlab::Utils::StrongMemoize
+
+      LIMIT_NAME = :web_hook_calls
+      NO_LIMIT = 0
+      # SystemHooks (instance admin hooks) and ServiceHooks (integration hooks)
+      # are not rate-limited.
+      EXCLUDED_HOOK_TYPES = %w(SystemHook ServiceHook).freeze
+
+      def initialize(hook)
+        @hook = hook
+        @parent = hook.parent
+      end
+
+      # Increments the rate-limit counter.
+      # Returns true if the hook should be rate-limited.
+      def rate_limit!
+        return false if no_limit?
+
+        ::Gitlab::ApplicationRateLimiter.throttled?(
+          limit_name,
+          scope: [root_namespace],
+          threshold: limit
+        )
+      end
+
+      # Returns true if the hook is currently over its rate-limit.
+      # It does not increment the rate-limit counter.
+      def rate_limited?
+        return false if no_limit?
+
+        Gitlab::ApplicationRateLimiter.peek(
+          limit_name,
+          scope: [root_namespace],
+          threshold: limit
+        )
+      end
+
+      def limit
+        strong_memoize(:limit) do
+          next NO_LIMIT if hook.class.name.in?(EXCLUDED_HOOK_TYPES)
+
+          root_namespace.actual_limits.limit_for(limit_name) || NO_LIMIT
+        end
+      end
+
+      private
+
+      attr_reader :hook, :parent
+
+      def no_limit?
+        limit == NO_LIMIT
+      end
+
+      def root_namespace
+        @root_namespace ||= parent.root_ancestor
+      end
+
+      def limit_name
+        LIMIT_NAME
+      end
+    end
+  end
+end
+
+Gitlab::WebHooks::RateLimiter.prepend_mod