First attempt

lib/ci/api/builds.rb

@@ -16,6 +16,15 @@ module Ci
           not_found! unless current_runner.active?
           update_runner_info
 
+          last_update = Gitlab::Redis.with { |redis| redis.get(current_runner_redis_key)}
+
+          if params[:last_update] != ""
+            if :last_update == last_update
+              headers 'X-GitLab-Last-Update', last_update
+              return build_not_found!
+            end
+          end
+
           build = Ci::RegisterBuildService.new.execute(current_runner)
 
           if build
@@ -26,6 +35,14 @@ module Ci
           else
             Gitlab::Metrics.add_event(:build_not_found)
 
+            if last_update == ""
+              Gitlab::Redis.with do |redis]
+                new_update = Time.new.inspect
+                redis.set(current_runner_redis_key, new_update, ex: 60.minutes)
+                headers 'X-GitLab-Last-Update', new_update
+              end
+            end
+
             build_not_found!
           end
         end

lib/ci/api/helpers.rb

@@ -60,6 +60,9 @@ module Ci
         @runner ||= Runner.find_by_token(params[:token].to_s)
       end
 
+      def current_runner_redis_key
+        @runner_redis_key ||= "#{current_runner.token}_#{current_runner.tag_list}"
+
       def get_runner_version_from_params
         return unless params["info"].present?
         attributes_for_keys(["name", "version", "revision", "platform", "architecture"], params["info"])