Expose pipeline metrics to /_node/stats/pipelines

Fixes #5472

logstash-core/lib/logstash/api/commands/stats.rb

@@ -33,6 +33,10 @@ module LogStash
           )
         end
 
+        def pipeline
+          service.get_shallow(:stats, :pipelines)
+        end
+
         def memory
           memory = service.get_shallow(:jvm, :memory)
           {

logstash-core/lib/logstash/api/modules/node_stats.rb

@@ -50,6 +50,10 @@ module LogStash
           respond_with :mem => mem_payload
         end
 
+        get "/pipeline" do
+          respond_with :pipeline => pipeline_payload
+        end
+
         private
 
         def events_payload
@@ -67,6 +71,10 @@ module LogStash
         def mem_payload
           @stats.memory
         end
+
+        def pipeline_payload
+          @stats.pipeline
+        end
       end
     end
   end