PMM-9458 Disable DBStats and TopMetrics where limit is active. (#417)

* PMM-9458 Proposed solution

* PMM-9458 Improve help-

Co-authored-by: Carlos Salguero <[email protected]>

Author: JiriCtvrtka

exporter/exporter.go

@@ -192,7 +192,7 @@ func (e *Exporter) makeRegistry(ctx context.Context, client *mongo.Client, topol
 		registry.MustRegister(&ddc)
 	}
 
-	if e.opts.EnableDBStats && requestOpts.EnableDBStats {
+	if e.opts.EnableDBStats && limitsOk && requestOpts.EnableDBStats {
 		cc := dbstatsCollector{
 			ctx:            ctx,
 			client:         client,
@@ -203,7 +203,7 @@ func (e *Exporter) makeRegistry(ctx context.Context, client *mongo.Client, topol
 		registry.MustRegister(&cc)
 	}
 
-	if e.opts.EnableTopMetrics && nodeType != typeMongos && requestOpts.EnableTopMetrics {
+	if e.opts.EnableTopMetrics && nodeType != typeMongos && limitsOk && requestOpts.EnableTopMetrics {
 		tc := topCollector{
 			ctx:            ctx,
 			client:         client,

main.go

@@ -53,7 +53,7 @@ type GlobalFlags struct {
 
 	CollectAll bool `name:"collect-all" help:"Enable all collectors. Same as specifying all --collector.<name>"`
 
-	CollStatsLimit int `name:"collector.collstats-limit" help:"Disable collstats, dbstat, topmetrics and indexstats collector if there are more than <n> collections. 0=No limit" default:"0"`
+	CollStatsLimit int `name:"collector.collstats-limit" help:"Disable collstats, dbstats, topmetrics and indexstats collector if there are more than <n> collections. 0=No limit" default:"0"`
 
 	DiscoveringMode bool `name:"discovering-mode" help:"Enable autodiscover collections" negatable:""`
 	CompatibleMode  bool `name:"compatible-mode" help:"Enable old mongodb-exporter compatible metrics" negatable:""`