Add flag to disable docker cpu metrics collection per core

CHANGELOG.asciidoc

@@ -66,6 +66,8 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha1...master[Check the HEAD d
 
 *Metricbeat*
 
+- Add setting to disable docker cpu metrics per core. {pull}9194[9194]
+
 *Packetbeat*
 
 *Functionbeat*

metricbeat/docs/modules/docker.asciidoc

@@ -50,6 +50,9 @@ metricbeat.modules:
   # If set to true, replace dots in labels with `_`.
   #labels.dedot: false
 
+  # If set to true, collects metrics per core.
+  #cpu.cores: true
+
   # To connect to Docker over TLS you must specify a client and CA certificate.
   #ssl:
     #certificate_authority: "/etc/pki/root/ca.pem"

metricbeat/metricbeat.reference.yml

@@ -178,6 +178,9 @@ metricbeat.modules:
   # If set to true, replace dots in labels with `_`.
   #labels.dedot: false
 
+  # If set to true, collects metrics per core.
+  #cpu.cores: true
+
   # To connect to Docker over TLS you must specify a client and CA certificate.
   #ssl:
     #certificate_authority: "/etc/pki/root/ca.pem"

metricbeat/module/docker/_meta/config.reference.yml

@@ -15,6 +15,9 @@
   # If set to true, replace dots in labels with `_`.
   #labels.dedot: false
 
+  # If set to true, collects metrics per core.
+  #cpu.cores: true
+
   # To connect to Docker over TLS you must specify a client and CA certificate.
   #ssl:
     #certificate_authority: "/etc/pki/root/ca.pem"

metricbeat/module/docker/cpu/cpu.go

@@ -51,10 +51,19 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 		return nil, err
 	}
 
+	cpuConfig := struct {
+		Cores bool `config:"cpu.cores"`
+	}{
+		Cores: true,
+	}
+	if err := base.Module().UnpackConfig(&cpuConfig); err != nil {
+		return nil, err
+	}
+
 	return &MetricSet{
 		BaseMetricSet: base,
 		dockerClient:  client,
-		cpuService:    &CPUService{},
+		cpuService:    &CPUService{Cores: cpuConfig.Cores},
 		dedot:         config.DeDot,
 	}, nil
 }

metricbeat/module/docker/cpu/helper.go

@@ -38,7 +38,10 @@ type CPUStats struct {
 	SystemUsagePercentage       float64
 }
 
-type CPUService struct{}
+// CPUService is a helper to collect docker CPU metrics
+type CPUService struct {
+	Cores bool
+}
 
 func NewCpuService() *CPUService {
 	return &CPUService{}
@@ -57,10 +60,9 @@ func (c *CPUService) getCPUStatsList(rawStats []docker.Stat, dedot bool) []CPUSt
 func (c *CPUService) getCPUStats(myRawStat *docker.Stat, dedot bool) CPUStats {
 	usage := cpuUsage{Stat: myRawStat}
 
-	return CPUStats{
+	stats := CPUStats{
 		Time:                        common.Time(myRawStat.Stats.Read),
 		Container:                   docker.NewContainer(myRawStat.Container, dedot),
-		PerCpuUsage:                 usage.PerCPU(),
 		TotalUsage:                  usage.Total(),
 		UsageInKernelmode:           myRawStat.Stats.CPUStats.CPUUsage.UsageInKernelmode,
 		UsageInKernelmodePercentage: usage.InKernelMode(),
@@ -69,6 +71,12 @@ func (c *CPUService) getCPUStats(myRawStat *docker.Stat, dedot bool) CPUStats {
 		SystemUsage:                 myRawStat.Stats.CPUStats.SystemUsage,
 		SystemUsagePercentage:       usage.System(),
 	}
+
+	if c.Cores {
+		stats.PerCpuUsage = usage.PerCPU()
+	}
+
+	return stats
 }
 
 // TODO: These helper should be merged with the cpu helper in system/cpu