Reuse connections in redis info metricset (elastic#12950)

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

CHANGELOG.next.asciidoc

@@ -148,7 +148,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - PdhExpandWildCardPathW will not expand counter paths in 32 bit windows systems, workaround will use a different function.{issue}12590[12590]{pull}12622[12622]
 - In the elasticsearch/node_stats metricset, if xpack is enabled, make parsing of ES node load average optional as ES on Windows doesn't report load average. {pull}12866[12866]
 - Ramdisk is not filtered out when collecting disk performance counters in diskio metricset {issue}12814[12814] {pull}12829[12829]
-- Fix connections leak in redis module {pull}12914[12914]
+- Fix connections leak in redis module {pull}12914[12914] {pull}12950[12950]
 - Fix wrong uptime reporting by system/uptime metricset under Windows. {pull}12915[12915]
 - Print errors that were being omitted in vSphere metricsets {pull}12816[12816]
 

metricbeat/module/redis/info/info.go

@@ -53,7 +53,11 @@ 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)
@@ -76,7 +80,7 @@ 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

@@ -72,7 +72,11 @@ 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

@@ -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("keyspace", conn)