Skip collection stats when disabled in mongodb input (#6364)

plugins/inputs/mongodb/README.md

@@ -13,8 +13,10 @@
 
   ## When true, collect per database stats
   # gather_perdb_stats = false
+
   ## When true, collect per collection stats
   # gather_col_stats = false
+
   ## List of db where collections stats are collected
   ## If empty, all db are concerned
   # col_stats_dbs = ["local"]

plugins/inputs/mongodb/mongodb.go

@@ -42,8 +42,10 @@ var sampleConfig = `
 
   ## When true, collect per database stats
   # gather_perdb_stats = false
+
   ## When true, collect per collection stats
   # gather_col_stats = false
+
   ## List of db where collections stats are collected
   ## If empty, all db are concerned
   # col_stats_dbs = ["local"]
@@ -177,7 +179,8 @@ func (m *MongoDB) gatherServer(server *Server, acc telegraf.Accumulator) error {
 func init() {
 	inputs.Add("mongodb", func() telegraf.Input {
 		return &MongoDB{
-			mongos: make(map[string]*Server),
+			ColStatsDbs: []string{"local"},
+			mongos:      make(map[string]*Server),
 		}
 	})
 }

plugins/inputs/mongodb/mongodb_server.go

@@ -227,9 +227,13 @@ func (s *Server) gatherData(acc telegraf.Accumulator, gatherDbStats bool, gather
 			authLogLevel(err), err)
 	}
 
-	collectionStats, err := s.gatherCollectionStats(colStatsDbs)
-	if err != nil {
-		return err
+	var collectionStats *ColStats
+	if gatherColStats {
+		stats, err := s.gatherCollectionStats(colStatsDbs)
+		if err != nil {
+			return err
+		}
+		collectionStats = stats
 	}
 
 	dbStats := &DbStats{}

plugins/inputs/mongodb/mongostat.go

@@ -961,24 +961,25 @@ func NewStatLine(oldMongo, newMongo MongoStatus, key string, all bool, sampleSec
 		}
 	}
 
-	newColStats := *newMongo.ColStats
-	for _, col := range newColStats.Collections {
-		colStatsData := col.ColStatsData
-		// mongos doesn't have the db key, so setting the db name
-		if colStatsData.Collection == "" {
-			colStatsData.Collection = col.Name
+	if newMongo.ColStats != nil {
+		for _, col := range newMongo.ColStats.Collections {
+			colStatsData := col.ColStatsData
+			// mongos doesn't have the db key, so setting the db name
+			if colStatsData.Collection == "" {
+				colStatsData.Collection = col.Name
+			}
+			colStatLine := &ColStatLine{
+				Name:           colStatsData.Collection,
+				DbName:         col.DbName,
+				Count:          colStatsData.Count,
+				Size:           colStatsData.Size,
+				AvgObjSize:     colStatsData.AvgObjSize,
+				StorageSize:    colStatsData.StorageSize,
+				TotalIndexSize: colStatsData.TotalIndexSize,
+				Ok:             colStatsData.Ok,
+			}
+			returnVal.ColStatsLines = append(returnVal.ColStatsLines, *colStatLine)
 		}
-		colStatLine := &ColStatLine{
-			Name:           colStatsData.Collection,
-			DbName:         col.DbName,
-			Count:          colStatsData.Count,
-			Size:           colStatsData.Size,
-			AvgObjSize:     colStatsData.AvgObjSize,
-			StorageSize:    colStatsData.StorageSize,
-			TotalIndexSize: colStatsData.TotalIndexSize,
-			Ok:             colStatsData.Ok,
-		}
-		returnVal.ColStatsLines = append(returnVal.ColStatsLines, *colStatLine)
 	}
 
 	// Set shard stats