[metricbeat] implement Close() for docker metricsets (#11294) (#11340)

* implement Close() for docker metricsets

(cherry picked from commit 57f8b5c)

CHANGELOG.next.asciidoc

@@ -95,6 +95,7 @@ https://github.com/elastic/beats/compare/v7.0.0-beta1...master[Check the HEAD di
 - Add documentation about jolokia autodiscover fields. {issue}10925[10925] {pull}10979[10979]
 - Add missing aws.ec2.instance.state.name into fields.yml. {issue}11219[11219] {pull}11221[11221]
 - Fix ec2 metricset to collect metrics from Cloudwatch with the same timestamp. {pull}11142[11142]
+- Fix potential memory leak in stopped docker metricsets {pull}11294[11294]
 
 *Packetbeat*
 

metricbeat/module/docker/container/container.go

@@ -38,6 +38,7 @@ func init() {
 	)
 }
 
+// MetricSet type defines all fields of the MetricSet
 type MetricSet struct {
 	mb.BaseMetricSet
 	dockerClient *client.Client
@@ -76,3 +77,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	}
 	eventsMapping(r, containers, m.dedot)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/cpu/cpu.go

@@ -84,3 +84,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	formattedStats := m.cpuService.getCPUStatsList(stats, m.dedot)
 	eventsMapping(r, formattedStats)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/diskio/diskio.go

@@ -75,3 +75,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	formattedStats := m.blkioService.getBlkioStatsList(stats, m.dedot)
 	eventsMapping(r, formattedStats)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/healthcheck/healthcheck.go

@@ -76,3 +76,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	}
 	eventsMapping(r, containers, m)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/image/image.go

@@ -78,3 +78,9 @@ func (m *MetricSet) Fetch() ([]common.MapStr, error) {
 
 	return eventsMapping(images, m.dedot), nil
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/info/info.go

@@ -67,3 +67,9 @@ func (m *MetricSet) Fetch() (common.MapStr, error) {
 
 	return eventMapping(&info), nil
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/memory/memory.go

@@ -75,3 +75,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	memoryStats := m.memoryService.getMemoryStatsList(stats, m.dedot)
 	eventsMapping(r, memoryStats)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}

metricbeat/module/docker/network/network.go

@@ -77,3 +77,9 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) {
 	formattedStats := m.netService.getNetworkStatsPerContainer(stats, m.dedot)
 	eventsMapping(r, formattedStats)
 }
+
+//Close stops the metricset
+func (m *MetricSet) Close() error {
+
+	return m.dockerClient.Close()
+}