Calculate memory usage percentage in Windows kubernetes pods (#25428)

In Windows native containers usage memory is reported
using the workingSet. Use this value to calculate memory
usage percentage.

CHANGELOG.next.asciidoc

@@ -507,6 +507,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Fix GCP not able to request Cloudfunctions metrics if a region filter was set {pull}24218[24218]
 - Fix type of `uwsgi.status.worker.rss` type. {pull}24468[24468]
 - Accept text/plain type by default for prometheus client scraping. {pull}24622[24622]
+- Use working set bytes to calculate the pod memory limit pct when memory usage is not reported (ie. Windows pods). {pull}25428[25428]
 - Fix copy-paste error in libbeat docs. {pull}25448[25448]
 
 *Packetbeat*

metricbeat/module/kubernetes/pod/data.go

@@ -118,16 +118,26 @@ func eventMapping(content []byte, perfMetrics *util.PerfMetricsCache) ([]common.
 			podEvent.Put("cpu.usage.node.pct", float64(usageNanoCores)/1e9/nodeCores)
 		}
 
-		if nodeMem > 0 {
-			podEvent.Put("memory.usage.node.pct", float64(usageMem)/nodeMem)
-		}
-
 		if coresLimit > 0 {
 			podEvent.Put("cpu.usage.limit.pct", float64(usageNanoCores)/1e9/coresLimit)
 		}
 
-		if memLimit > 0 {
-			podEvent.Put("memory.usage.limit.pct", float64(usageMem)/memLimit)
+		if usageMem > 0 {
+			if nodeMem > 0 {
+				podEvent.Put("memory.usage.node.pct", float64(usageMem)/nodeMem)
+			}
+			if memLimit > 0 {
+				podEvent.Put("memory.usage.limit.pct", float64(usageMem)/memLimit)
+			}
+		}
+
+		if workingSet > 0 && usageMem == 0 {
+			if nodeMem > 0 {
+				podEvent.Put("memory.usage.node.pct", float64(workingSet)/nodeMem)
+			}
+			if memLimit > 0 {
+				podEvent.Put("memory.usage.limit.pct", float64(workingSet)/memLimit)
+			}
 		}
 
 		events = append(events, podEvent)