Add option to disable mongodb cluster status (influxdata#7515)

It can be expensive to compute these metrics. In particular, when retrieveing the amount of jumbo chunks, an index is not being used and consequently the query triggers an expensive COLLSCAN. For big databases, this query has negative impact on the cluster performance.
idohalevi · Sep 23, 2020 · e67697e · e67697e
1 parent 5e37cb5
commit e67697e
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Showing 3 changed files with 31 additions and 13 deletions.
diff --git a/plugins/inputs/mongodb/README.md b/plugins/inputs/mongodb/README.md
@@ -11,6 +11,11 @@
   ##   mongodb://10.10.3.33:18832,
   servers = ["mongodb://127.0.0.1:27017"]
 
+  ## When true, collect cluster status.
+  ## Note that the query that counts jumbo chunks triggers a COLLSCAN, which
+  ## may have an impact on performance.
+  # gather_cluster_status = true
+
   ## When true, collect per database stats
   # gather_perdb_stats = false
 

diff --git a/plugins/inputs/mongodb/mongodb.go b/plugins/inputs/mongodb/mongodb.go
@@ -17,12 +17,13 @@ import (
 )
 
 type MongoDB struct {
-	Servers          []string
-	Ssl              Ssl
-	mongos           map[string]*Server
-	GatherPerdbStats bool
-	GatherColStats   bool
-	ColStatsDbs      []string
+	Servers             []string
+	Ssl                 Ssl
+	mongos              map[string]*Server
+	GatherClusterStatus bool
+	GatherPerdbStats    bool
+	GatherColStats      bool
+	ColStatsDbs         []string
 	tlsint.ClientConfig
 
 	Log telegraf.Logger
@@ -41,6 +42,11 @@ var sampleConfig = `
   ##   mongodb://10.10.3.33:18832,
   servers = ["mongodb://127.0.0.1:27017"]
 
+  ## When true, collect cluster status
+  ## Note that the query that counts jumbo chunks triggers a COLLSCAN, which
+  ## may have an impact on performance.
+  # gather_cluster_status = true
+
   ## When true, collect per database stats
   # gather_perdb_stats = false
 
@@ -177,14 +183,17 @@ func (m *MongoDB) gatherServer(server *Server, acc telegraf.Accumulator) error {
 		}
 		server.Session = sess
 	}
-	return server.gatherData(acc, m.GatherPerdbStats, m.GatherColStats, m.ColStatsDbs)
+	return server.gatherData(acc, m.GatherClusterStatus, m.GatherPerdbStats, m.GatherColStats, m.ColStatsDbs)
 }
 
 func init() {
 	inputs.Add("mongodb", func() telegraf.Input {
 		return &MongoDB{
-			ColStatsDbs: []string{"local"},
-			mongos:      make(map[string]*Server),
+			mongos:              make(map[string]*Server),
+			GatherClusterStatus: true,
+			GatherPerdbStats:    false,
+			GatherColStats:      false,
+			ColStatsDbs:         []string{"local"},
 		}
 	})
 }
diff --git a/plugins/inputs/mongodb/mongodb_server.go b/plugins/inputs/mongodb/mongodb_server.go
@@ -192,7 +192,7 @@ func (s *Server) gatherCollectionStats(colStatsDbs []string) (*ColStats, error)
 	return results, nil
 }
 
-func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool, gatherColStats bool, colStatsDbs []string) error {
+func (s *Server) gatherData(acc telegraf.Accumulator, gatherClusterStatus bool, gatherDbStats bool, gatherColStats bool, colStatsDbs []string) error {
 	s.Session.SetMode(mgo.Eventual, true)
 	s.Session.SetSocketTimeout(0)
 
@@ -218,9 +218,13 @@ func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool, gather
 		}
 	}
 
-	clusterStatus, err := s.gatherClusterStatus()
-	if err != nil {
-		s.Log.Debugf("Unable to gather cluster status: %s", err.Error())
+	var clusterStatus *ClusterStatus
+	if gatherClusterStatus {
+		status, err := s.gatherClusterStatus()
+		if err != nil {
+			s.Log.Debugf("Unable to gather cluster status: %s", err.Error())
+		}
+		clusterStatus = status
 	}
 
 	shardStats, err := s.gatherShardConnPoolStats()