[8.15](backport #41022) [AWS] Use namespace for GetListMetrics when exists (#41175)

* [AWS] Use namespace for GetListMetrics when exists (#41022)

* Use namespace for GetListMetrics when exists

(cherry picked from commit 36327a4)

---------

Co-authored-by: kaiyan-sheng <kaiyan.sheng@elastic.co>

Author: mergify[bot]

CHANGELOG.next.asciidoc

@@ -124,6 +124,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Fix Azure Monitor 429 error by causing metricbeat to retry the request again. {pull}38294[38294]
 - Fix fields not being parsed correctly in postgresql/database {issue}25301[25301] {pull}37720[37720]
 - rabbitmq/queue - Change the mapping type of `rabbitmq.queue.consumers.utilisation.pct` to `scaled_float` from `long` because the values fall within the range of `[0.0, 1.0]`. Previously, conversion to integer resulted in reporting either `0` or `1`.
+- Use namespace for GetListMetrics when exists in AWS {pull}41022[41022]
 
 *Osquerybeat*
 

metricbeat/docs/modules/aws.asciidoc

@@ -329,7 +329,8 @@ GetMetricData max page size: 100, based on https://docs.aws.amazon.com/AmazonClo
 | IAM ListAccountAliases | 1 | Once on startup
 | STS GetCallerIdentity | 1 | Once on startup
 | EC2 DescribeRegions| 1 | Once on startup
-| CloudWatch ListMetrics | Total number of results / ListMetrics max page size | Per region per collection period
+| CloudWatch ListMetrics without specifying namespace in configuration | Total number of results / ListMetrics max page size | Per region per collection period
+| CloudWatch ListMetrics with specific namespaces in configuration | Total number of results / ListMetrics max page size * number of unique namespaces | Per region per collection period
 | CloudWatch GetMetricData | Total number of results / GetMetricData max page size | Per region per namespace per collection period
 |===
 `billing`, `ebs`, `elb`, `sns`, `usage` and `lambda` are the same as `cloudwatch` metricset.

x-pack/metricbeat/module/aws/_meta/docs.asciidoc

@@ -317,7 +317,8 @@ GetMetricData max page size: 100, based on https://docs.aws.amazon.com/AmazonClo
 | IAM ListAccountAliases | 1 | Once on startup
 | STS GetCallerIdentity | 1 | Once on startup
 | EC2 DescribeRegions| 1 | Once on startup
-| CloudWatch ListMetrics | Total number of results / ListMetrics max page size | Per region per collection period
+| CloudWatch ListMetrics without specifying namespace in configuration | Total number of results / ListMetrics max page size | Per region per collection period
+| CloudWatch ListMetrics with specific namespaces in configuration | Total number of results / ListMetrics max page size * number of unique namespaces | Per region per collection period
 | CloudWatch GetMetricData | Total number of results / GetMetricData max page size | Per region per namespace per collection period
 |===
 `billing`, `ebs`, `elb`, `sns`, `usage` and `lambda` are the same as `cloudwatch` metricset.

x-pack/metricbeat/module/aws/cloudwatch/cloudwatch.go

@@ -179,10 +179,22 @@ func (m *MetricSet) Fetch(report mb.ReporterV2) error {
 			continue
 		}
 
-		// retrieve all the details for all the metrics available in the current region
-		listMetricsOutput, err := aws.GetListMetricsOutput("*", regionName, m.Period, m.IncludeLinkedAccounts, m.OwningAccount, m.MonitoringAccountID, svcCloudwatch)
-		if err != nil {
-			m.Logger().Errorf("Error while retrieving the list of metrics for region %s: %w", regionName, err)
+		// retrieve all the details for all the metrics available in the current region when no namespace is specified
+		// otherwise only retrieve metrics from the specific namespaces from the config
+		var listMetricsOutput []aws.MetricWithID
+		if len(namespaceDetailTotal) == 0 {
+			listMetricsOutput, err = aws.GetListMetricsOutput("*", regionName, m.Period, m.IncludeLinkedAccounts, m.OwningAccount, m.MonitoringAccountID, svcCloudwatch)
+			if err != nil {
+				m.Logger().Errorf("Error while retrieving the list of metrics for region %s and namespace %s: %w", regionName, "*", err)
+			}
+		} else {
+			for namespace := range namespaceDetailTotal {
+				listMetricsOutputPerNamespace, err := aws.GetListMetricsOutput(namespace, regionName, m.Period, m.IncludeLinkedAccounts, m.OwningAccount, m.MonitoringAccountID, svcCloudwatch)
+				if err != nil {
+					m.Logger().Errorf("Error while retrieving the list of metrics for region %s and namespace %s: %w", regionName, namespace, err)
+				}
+				listMetricsOutput = append(listMetricsOutput, listMetricsOutputPerNamespace...)
+			}
 		}
 
 		if len(listMetricsOutput) == 0 {