Reuse connections in redis info metricset (elastic#12950) (elastic#12979

)

Reuse connections in redis info metricset, and log close
errors at the debug level.

(cherry picked from commit d9e4e9b)

CHANGELOG.next.asciidoc

@@ -40,7 +40,7 @@ https://github.com/elastic/beats/compare/v7.2.0...7.2[Check the HEAD diff]
 
 *Metricbeat*
 
-- Fix connections leak in redis module {pull}12914[12914]
+- Fix connections leak in redis module {pull}12914[12914] {pull}12950[12950]
 
 *Packetbeat*
 

metricbeat/module/redis/info/info.go

@@ -51,7 +51,11 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 // Fetch fetches metrics from Redis by issuing the INFO command.
 func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 	conn := m.Connection()
-	defer conn.Close()
+	defer func() {
+		if err := conn.Close(); err != nil {
+			m.Logger().Debug(errors.Wrapf(err, "failed to release connection"))
+		}
+	}()
 
 	// Fetch default INFO.
 	info, err := redis.FetchRedisInfo("default", conn)
@@ -74,7 +78,7 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 		}
 	}
 
-	slowLogLength, err := redis.FetchSlowLogLength(m.Connection())
+	slowLogLength, err := redis.FetchSlowLogLength(conn)
 	if err != nil {
 		return errors.Wrap(err, "failed to fetch slow log length")
 

metricbeat/module/redis/key/key.go

@@ -70,7 +70,11 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 // Fetch fetches information from Redis keys
 func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 	conn := m.Connection()
-	defer conn.Close()
+	defer func() {
+		if err := conn.Close(); err != nil {
+			m.Logger().Debug(errors.Wrapf(err, "failed to release connection"))
+		}
+	}()
 
 	for _, p := range m.patterns {
 		if err := redis.Select(conn, p.Keyspace); err != nil {

metricbeat/module/redis/keyspace/keyspace.go

@@ -49,7 +49,11 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 // Fetch fetches metrics from Redis by issuing the INFO command.
 func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 	conn := m.Connection()
-	defer conn.Close()
+	defer func() {
+		if err := conn.Close(); err != nil {
+			m.Logger().Debug(errors.Wrapf(err, "failed to release connection"))
+		}
+	}()
 
 	// Fetch default INFO.
 	info, err := redis.FetchRedisInfo("keyspace", conn)