[metricbeat] check for a valid limit before we process a memory event (…

…elastic#11676)

* check for a valid limit before we process a memory event

(cherry picked from commit 97aec9b)

CHANGELOG.next.asciidoc

@@ -82,6 +82,9 @@ https://github.com/elastic/beats/compare/v7.0.0...7.0[Check the HEAD diff]
 
 *Metricbeat*
 
+- Add _bucket to histogram metrics in Prometheus Collector {pull}11578[11578]
+- Prevent the docker/memory metricset from processing invalid events before container start {pull}11676[11676]
+
 *Packetbeat*
 
 *Winlogbeat*

metricbeat/module/docker/memory/helper.go

@@ -22,6 +22,7 @@ import (
  "github.com/elastic/beats/metricbeat/module/docker"
 )
 
+// MemoryData contains parsed container memory info
 type MemoryData struct {
  Time common.Time
  Container *docker.Container
@@ -34,12 +35,19 @@ type MemoryData struct {
  UsageP float64
 }
 
+// MemoryService is placeholder for the the memory stat parsers
 type MemoryService struct{}
 
-func (s *MemoryService) getMemoryStatsList(rawStats []docker.Stat, dedot bool) []MemoryData {
+func (s *MemoryService) getMemoryStatsList(containers []docker.Stat, dedot bool) []MemoryData {
  formattedStats := []MemoryData{}
- for _, myRawStats := range rawStats {
- formattedStats = append(formattedStats, s.getMemoryStats(myRawStats, dedot))
+ for _, containerStats := range containers {
+ //There appears to be a race where a container will report with a stat object before it actually starts
+ //during this time, there doesn't appear to be any meaningful data,
+ // and Limit will never be 0 unless the container is not running & there's no cgroup data
+ if containerStats.Stats.MemoryStats.Limit == 0 {
+ continue
+ }
+ formattedStats = append(formattedStats, s.getMemoryStats(containerStats, dedot))
  }
 
  return formattedStats

metricbeat/module/docker/memory/memory.go

@@ -35,6 +35,7 @@ func init() {
  )
 }
 
+// MetricSet type defines all fields of the MetricSet
 type MetricSet struct {
  mb.BaseMetricSet
  memoryService *MemoryService