Add shard server stats to the mongodb input plugin (#3808)

plugins/inputs/mongodb/mongodb_server.go

@@ -55,8 +55,18 @@ func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool) error
 		JumboChunksCount: int64(jumbo_chunks),
 	}
 
-	result_db_stats := &DbStats{}
+	resultShards := &ShardStats{}
+	err = s.Session.DB("admin").Run(bson.D{
+		{
+			Name:  "shardConnPoolStats",
+			Value: 1,
+		},
+	}, &resultShards)
+	if err != nil {
+		log.Println("E! Error getting database shard stats (" + err.Error() + ")")
+	}
 
+	result_db_stats := &DbStats{}
 	if gatherDbStats == true {
 		names := []string{}
 		names, err = s.Session.DatabaseNames()
@@ -88,6 +98,7 @@ func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool) error
 		ReplSetStatus: result_repl,
 		ClusterStatus: result_cluster,
 		DbStats:       result_db_stats,
+		ShardStats:    resultShards,
 	}
 
 	defer func() {