stats.go

/*
Copyright 2019 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package kubelet

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"sync"
	"text/tabwriter"
	"time"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	utilerrors "k8s.io/apimachinery/pkg/util/errors"
	"k8s.io/apimachinery/pkg/util/wait"

	clientset "k8s.io/client-go/kubernetes"
	restclient "k8s.io/client-go/rest"
	kubeletstatsv1alpha1 "k8s.io/kubernetes/pkg/kubelet/apis/stats/v1alpha1"
	dockermetrics "k8s.io/kubernetes/pkg/kubelet/dockershim/metrics"
	"k8s.io/kubernetes/pkg/master/ports"
	"k8s.io/kubernetes/test/e2e/framework"
	e2emetrics "k8s.io/kubernetes/test/e2e/framework/metrics"
)

const (
	// timeout for proxy requests.
	proxyTimeout = 2 * time.Minute
)

// ContainerResourceUsage is a structure for gathering container resource usage.
type ContainerResourceUsage struct {
	Name                    string
	Timestamp               time.Time
	CPUUsageInCores         float64
	MemoryUsageInBytes      uint64
	MemoryWorkingSetInBytes uint64
	MemoryRSSInBytes        uint64
	// The interval used to calculate CPUUsageInCores.
	CPUInterval time.Duration
}

// ResourceUsagePerContainer is map of ContainerResourceUsage
type ResourceUsagePerContainer map[string]*ContainerResourceUsage

// ResourceUsagePerNode is map of ResourceUsagePerContainer.
type ResourceUsagePerNode map[string]ResourceUsagePerContainer

// ContainersCPUSummary is indexed by the container name with each entry a
// (percentile, value) map.
type ContainersCPUSummary map[string]map[float64]float64

// NodesCPUSummary is indexed by the node name with each entry a
// ContainersCPUSummary map.
type NodesCPUSummary map[string]ContainersCPUSummary

// RuntimeOperationMonitor is the tool getting and parsing docker operation metrics.
type RuntimeOperationMonitor struct {
	client          clientset.Interface
	nodesRuntimeOps map[string]NodeRuntimeOperationErrorRate
}

// NodeRuntimeOperationErrorRate is the runtime operation error rate on one node.
type NodeRuntimeOperationErrorRate map[string]*RuntimeOperationErrorRate

// RuntimeOperationErrorRate is the error rate of a specified runtime operation.
type RuntimeOperationErrorRate struct {
	TotalNumber float64
	ErrorRate   float64
	TimeoutRate float64
}

// ProxyRequest performs a get on a node proxy endpoint given the nodename and rest client.
func ProxyRequest(c clientset.Interface, node, endpoint string, port int) (restclient.Result, error) {
	// proxy tends to hang in some cases when Node is not ready. Add an artificial timeout for this call. #22165
	var result restclient.Result
	finished := make(chan struct{}, 1)
	go func() {
		result = c.CoreV1().RESTClient().Get().
			Resource("nodes").
			SubResource("proxy").
			Name(fmt.Sprintf("%v:%v", node, port)).
			Suffix(endpoint).
			Do(context.TODO())

		finished <- struct{}{}
	}()
	select {
	case <-finished:
		return result, nil
	case <-time.After(proxyTimeout):
		return restclient.Result{}, nil
	}
}

// NewRuntimeOperationMonitor returns a new RuntimeOperationMonitor.
func NewRuntimeOperationMonitor(c clientset.Interface) *RuntimeOperationMonitor {
	m := &RuntimeOperationMonitor{
		client:          c,
		nodesRuntimeOps: make(map[string]NodeRuntimeOperationErrorRate),
	}
	nodes, err := m.client.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{})
	if err != nil {
		framework.Failf("RuntimeOperationMonitor: unable to get list of nodes: %v", err)
	}
	for _, node := range nodes.Items {
		m.nodesRuntimeOps[node.Name] = make(NodeRuntimeOperationErrorRate)
	}
	// Initialize the runtime operation error rate
	m.GetRuntimeOperationErrorRate()
	return m
}

// GetRuntimeOperationErrorRate gets runtime operation records from kubelet metrics and calculate
// error rates of all runtime operations.
func (m *RuntimeOperationMonitor) GetRuntimeOperationErrorRate() map[string]NodeRuntimeOperationErrorRate {
	for node := range m.nodesRuntimeOps {
		nodeResult, err := getNodeRuntimeOperationErrorRate(m.client, node)
		if err != nil {
			framework.Logf("GetRuntimeOperationErrorRate: unable to get kubelet metrics from node %q: %v", node, err)
			continue
		}
		m.nodesRuntimeOps[node] = nodeResult
	}
	return m.nodesRuntimeOps
}

// GetLatestRuntimeOperationErrorRate gets latest error rate and timeout rate from last observed RuntimeOperationErrorRate.
func (m *RuntimeOperationMonitor) GetLatestRuntimeOperationErrorRate() map[string]NodeRuntimeOperationErrorRate {
	result := make(map[string]NodeRuntimeOperationErrorRate)
	for node := range m.nodesRuntimeOps {
		result[node] = make(NodeRuntimeOperationErrorRate)
		oldNodeResult := m.nodesRuntimeOps[node]
		curNodeResult, err := getNodeRuntimeOperationErrorRate(m.client, node)
		if err != nil {
			framework.Logf("GetLatestRuntimeOperationErrorRate: unable to get kubelet metrics from node %q: %v", node, err)
			continue
		}
		for op, cur := range curNodeResult {
			t := *cur
			if old, found := oldNodeResult[op]; found {
				t.ErrorRate = (t.ErrorRate*t.TotalNumber - old.ErrorRate*old.TotalNumber) / (t.TotalNumber - old.TotalNumber)
				t.TimeoutRate = (t.TimeoutRate*t.TotalNumber - old.TimeoutRate*old.TotalNumber) / (t.TotalNumber - old.TotalNumber)
				t.TotalNumber -= old.TotalNumber
			}
			result[node][op] = &t
		}
		m.nodesRuntimeOps[node] = curNodeResult
	}
	return result
}

// FormatRuntimeOperationErrorRate formats the runtime operation error rate to string.
func FormatRuntimeOperationErrorRate(nodesResult map[string]NodeRuntimeOperationErrorRate) string {
	lines := []string{}
	for node, nodeResult := range nodesResult {
		lines = append(lines, fmt.Sprintf("node %q runtime operation error rate:", node))
		for op, result := range nodeResult {
			line := fmt.Sprintf("operation %q: total - %.0f; error rate - %f; timeout rate - %f", op,
				result.TotalNumber, result.ErrorRate, result.TimeoutRate)
			lines = append(lines, line)
		}
		lines = append(lines, fmt.Sprintln())
	}
	return strings.Join(lines, "\n")
}

// getNodeRuntimeOperationErrorRate gets runtime operation error rate from specified node.
func getNodeRuntimeOperationErrorRate(c clientset.Interface, node string) (NodeRuntimeOperationErrorRate, error) {
	result := make(NodeRuntimeOperationErrorRate)
	ms, err := e2emetrics.GetKubeletMetrics(c, node)
	if err != nil {
		return result, err
	}
	// If no corresponding metrics are found, the returned samples will be empty. Then the following
	// loop will be skipped automatically.
	allOps := ms[dockermetrics.DockerOperationsKey]
	errOps := ms[dockermetrics.DockerOperationsErrorsKey]
	timeoutOps := ms[dockermetrics.DockerOperationsTimeoutKey]
	for _, sample := range allOps {
		operation := string(sample.Metric["operation_type"])
		result[operation] = &RuntimeOperationErrorRate{TotalNumber: float64(sample.Value)}
	}
	for _, sample := range errOps {
		operation := string(sample.Metric["operation_type"])
		// Should always find the corresponding item, just in case
		if _, found := result[operation]; found {
			result[operation].ErrorRate = float64(sample.Value) / result[operation].TotalNumber
		}
	}
	for _, sample := range timeoutOps {
		operation := string(sample.Metric["operation_type"])
		if _, found := result[operation]; found {
			result[operation].TimeoutRate = float64(sample.Value) / result[operation].TotalNumber
		}
	}
	return result, nil
}

// GetStatsSummary contacts kubelet for the container information.
func GetStatsSummary(c clientset.Interface, nodeName string) (*kubeletstatsv1alpha1.Summary, error) {
	ctx, cancel := context.WithTimeout(context.Background(), framework.SingleCallTimeout)
	defer cancel()

	data, err := c.CoreV1().RESTClient().Get().
		Resource("nodes").
		SubResource("proxy").
		Name(fmt.Sprintf("%v:%v", nodeName, ports.KubeletPort)).
		Suffix("stats/summary").
		Do(ctx).Raw()

	if err != nil {
		return nil, err
	}

	summary := kubeletstatsv1alpha1.Summary{}
	err = json.Unmarshal(data, &summary)
	if err != nil {
		return nil, err
	}
	return &summary, nil
}

func getNodeStatsSummary(c clientset.Interface, nodeName string) (*kubeletstatsv1alpha1.Summary, error) {
	data, err := c.CoreV1().RESTClient().Get().
		Resource("nodes").
		SubResource("proxy").
		Name(fmt.Sprintf("%v:%v", nodeName, ports.KubeletPort)).
		Suffix("stats/summary").
		SetHeader("Content-Type", "application/json").
		Do(context.TODO()).Raw()

	if err != nil {
		return nil, err
	}

	var summary *kubeletstatsv1alpha1.Summary
	err = json.Unmarshal(data, &summary)
	if err != nil {
		return nil, err
	}
	return summary, nil
}

func getSystemContainerStats(summary *kubeletstatsv1alpha1.Summary) map[string]*kubeletstatsv1alpha1.ContainerStats {
	statsList := summary.Node.SystemContainers
	statsMap := make(map[string]*kubeletstatsv1alpha1.ContainerStats)
	for i := range statsList {
		statsMap[statsList[i].Name] = &statsList[i]
	}

	// Create a root container stats using information available in
	// stats.NodeStats. This is necessary since it is a different type.
	statsMap[rootContainerName] = &kubeletstatsv1alpha1.ContainerStats{
		CPU:    summary.Node.CPU,
		Memory: summary.Node.Memory,
	}
	return statsMap
}

const (
	rootContainerName = "/"
)

// TargetContainers returns a list of containers for which we want to collect resource usage.
func TargetContainers() []string {
	return []string{
		rootContainerName,
		kubeletstatsv1alpha1.SystemContainerRuntime,
		kubeletstatsv1alpha1.SystemContainerKubelet,
	}
}

func formatResourceUsageStats(nodeName string, containerStats ResourceUsagePerContainer) string {
	// Example output:
	//
	// Resource usage for node "e2e-test-foo-node-abcde":
	// container        cpu(cores)  memory(MB)
	// "/"              0.363       2942.09
	// "/docker-daemon" 0.088       521.80
	// "/kubelet"       0.086       424.37
	// "/system"        0.007       119.88
	buf := &bytes.Buffer{}
	w := tabwriter.NewWriter(buf, 1, 0, 1, ' ', 0)
	fmt.Fprintf(w, "container\tcpu(cores)\tmemory_working_set(MB)\tmemory_rss(MB)\n")
	for name, s := range containerStats {
		fmt.Fprintf(w, "%q\t%.3f\t%.2f\t%.2f\n", name, s.CPUUsageInCores, float64(s.MemoryWorkingSetInBytes)/(1024*1024), float64(s.MemoryRSSInBytes)/(1024*1024))
	}
	w.Flush()
	return fmt.Sprintf("Resource usage on node %q:\n%s", nodeName, buf.String())
}

// GetKubeletHeapStats returns stats of kubelet heap.
func GetKubeletHeapStats(c clientset.Interface, nodeName string) (string, error) {
	client, err := ProxyRequest(c, nodeName, "debug/pprof/heap", ports.KubeletPort)
	if err != nil {
		return "", err
	}
	raw, errRaw := client.Raw()
	if errRaw != nil {
		return "", err
	}
	kubeletstatsv1alpha1 := string(raw)
	// Only dumping the runtime.MemStats numbers to avoid polluting the log.
	numLines := 23
	lines := strings.Split(kubeletstatsv1alpha1, "\n")
	return strings.Join(lines[len(lines)-numLines:], "\n"), nil
}

func computeContainerResourceUsage(name string, oldStats, newStats *kubeletstatsv1alpha1.ContainerStats) *ContainerResourceUsage {
	return &ContainerResourceUsage{
		Name:                    name,
		Timestamp:               newStats.CPU.Time.Time,
		CPUUsageInCores:         float64(*newStats.CPU.UsageCoreNanoSeconds-*oldStats.CPU.UsageCoreNanoSeconds) / float64(newStats.CPU.Time.Time.Sub(oldStats.CPU.Time.Time).Nanoseconds()),
		MemoryUsageInBytes:      *newStats.Memory.UsageBytes,
		MemoryWorkingSetInBytes: *newStats.Memory.WorkingSetBytes,
		MemoryRSSInBytes:        *newStats.Memory.RSSBytes,
		CPUInterval:             newStats.CPU.Time.Time.Sub(oldStats.CPU.Time.Time),
	}
}

// resourceCollector periodically polls the node, collect stats for a given
// list of containers, computes and cache resource usage up to
// maxEntriesPerContainer for each container.
type resourceCollector struct {
	lock            sync.RWMutex
	node            string
	containers      []string
	client          clientset.Interface
	buffers         map[string][]*ContainerResourceUsage
	pollingInterval time.Duration
	stopCh          chan struct{}
}

func newResourceCollector(c clientset.Interface, nodeName string, containerNames []string, pollingInterval time.Duration) *resourceCollector {
	buffers := make(map[string][]*ContainerResourceUsage)
	return &resourceCollector{
		node:            nodeName,
		containers:      containerNames,
		client:          c,
		buffers:         buffers,
		pollingInterval: pollingInterval,
	}
}

// Start starts a goroutine to Poll the node every pollingInterval.
func (r *resourceCollector) Start() {
	r.stopCh = make(chan struct{}, 1)
	// Keep the last observed stats for comparison.
	oldStats := make(map[string]*kubeletstatsv1alpha1.ContainerStats)
	go wait.Until(func() { r.collectStats(oldStats) }, r.pollingInterval, r.stopCh)
}

// Stop sends a signal to terminate the stats collecting goroutine.
func (r *resourceCollector) Stop() {
	close(r.stopCh)
}

// collectStats gets the latest stats from kubelet stats summary API, computes
// the resource usage, and pushes it to the buffer.
func (r *resourceCollector) collectStats(oldStatsMap map[string]*kubeletstatsv1alpha1.ContainerStats) {
	summary, err := getNodeStatsSummary(r.client, r.node)
	if err != nil {
		framework.Logf("Error getting node stats summary on %q, err: %v", r.node, err)
		return
	}
	cStatsMap := getSystemContainerStats(summary)
	r.lock.Lock()
	defer r.lock.Unlock()
	for _, name := range r.containers {
		cStats, ok := cStatsMap[name]
		if !ok {
			framework.Logf("Missing info/stats for container %q on node %q", name, r.node)
			return
		}

		if oldStats, ok := oldStatsMap[name]; ok {
			if oldStats.CPU == nil || cStats.CPU == nil || oldStats.Memory == nil || cStats.Memory == nil {
				continue
			}
			if oldStats.CPU.Time.Equal(&cStats.CPU.Time) {
				// No change -> skip this stat.
				continue
			}
			r.buffers[name] = append(r.buffers[name], computeContainerResourceUsage(name, oldStats, cStats))
		}
		// Update the old stats.
		oldStatsMap[name] = cStats
	}
}

func (r *resourceCollector) GetLatest() (ResourceUsagePerContainer, error) {
	r.lock.RLock()
	defer r.lock.RUnlock()
	kubeletstatsv1alpha1 := make(ResourceUsagePerContainer)
	for _, name := range r.containers {
		contStats, ok := r.buffers[name]
		if !ok || len(contStats) == 0 {
			return nil, fmt.Errorf("Resource usage on node %q is not ready yet", r.node)
		}
		kubeletstatsv1alpha1[name] = contStats[len(contStats)-1]
	}
	return kubeletstatsv1alpha1, nil
}

// Reset frees the stats and start over.
func (r *resourceCollector) Reset() {
	r.lock.Lock()
	defer r.lock.Unlock()
	for _, name := range r.containers {
		r.buffers[name] = []*ContainerResourceUsage{}
	}
}

type resourceUsageByCPU []*ContainerResourceUsage

func (r resourceUsageByCPU) Len() int           { return len(r) }
func (r resourceUsageByCPU) Swap(i, j int)      { r[i], r[j] = r[j], r[i] }
func (r resourceUsageByCPU) Less(i, j int) bool { return r[i].CPUUsageInCores < r[j].CPUUsageInCores }

// The percentiles to report.
var percentiles = [...]float64{0.05, 0.20, 0.50, 0.70, 0.90, 0.95, 0.99}

// GetBasicCPUStats returns the percentiles the cpu usage in cores for
// containerName. This method examines all data currently in the buffer.
func (r *resourceCollector) GetBasicCPUStats(containerName string) map[float64]float64 {
	r.lock.RLock()
	defer r.lock.RUnlock()
	result := make(map[float64]float64, len(percentiles))
	usages := r.buffers[containerName]
	sort.Sort(resourceUsageByCPU(usages))
	for _, q := range percentiles {
		index := int(float64(len(usages))*q) - 1
		if index < 0 {
			// We don't have enough data.
			result[q] = 0
			continue
		}
		result[q] = usages[index].CPUUsageInCores
	}
	return result
}

// ResourceMonitor manages a resourceCollector per node.
type ResourceMonitor struct {
	client          clientset.Interface
	containers      []string
	pollingInterval time.Duration
	collectors      map[string]*resourceCollector
}

// NewResourceMonitor returns a new ResourceMonitor.
func NewResourceMonitor(c clientset.Interface, containerNames []string, pollingInterval time.Duration) *ResourceMonitor {
	return &ResourceMonitor{
		containers:      containerNames,
		client:          c,
		pollingInterval: pollingInterval,
	}
}

// Start starts collectors.
func (r *ResourceMonitor) Start() {
	// It should be OK to monitor unschedulable Nodes
	nodes, err := r.client.CoreV1().Nodes().List(context.TODO(), metav1.ListOptions{})
	if err != nil {
		framework.Failf("ResourceMonitor: unable to get list of nodes: %v", err)
	}
	r.collectors = make(map[string]*resourceCollector, 0)
	for _, node := range nodes.Items {
		collector := newResourceCollector(r.client, node.Name, r.containers, r.pollingInterval)
		r.collectors[node.Name] = collector
		collector.Start()
	}
}

// Stop stops collectors.
func (r *ResourceMonitor) Stop() {
	for _, collector := range r.collectors {
		collector.Stop()
	}
}

// Reset resets collectors.
func (r *ResourceMonitor) Reset() {
	for _, collector := range r.collectors {
		collector.Reset()
	}
}

// LogLatest outputs the latest resource usage into log.
func (r *ResourceMonitor) LogLatest() {
	summary, err := r.GetLatest()
	if err != nil {
		framework.Logf("%v", err)
	}
	framework.Logf("%s", r.FormatResourceUsage(summary))
}

// FormatResourceUsage returns the formatted string for LogLatest().
// TODO(oomichi): This can be made to local function after making test/e2e/node/kubelet_perf.go use LogLatest directly instead.
func (r *ResourceMonitor) FormatResourceUsage(s ResourceUsagePerNode) string {
	summary := []string{}
	for node, usage := range s {
		summary = append(summary, formatResourceUsageStats(node, usage))
	}
	return strings.Join(summary, "\n")
}

// GetLatest returns the latest resource usage.
func (r *ResourceMonitor) GetLatest() (ResourceUsagePerNode, error) {
	result := make(ResourceUsagePerNode)
	errs := []error{}
	for key, collector := range r.collectors {
		s, err := collector.GetLatest()
		if err != nil {
			errs = append(errs, err)
			continue
		}
		result[key] = s
	}
	return result, utilerrors.NewAggregate(errs)
}

// GetMasterNodeLatest returns the latest resource usage of master and node.
func (r *ResourceMonitor) GetMasterNodeLatest(usagePerNode ResourceUsagePerNode) ResourceUsagePerNode {
	result := make(ResourceUsagePerNode)
	var masterUsage ResourceUsagePerContainer
	var nodesUsage []ResourceUsagePerContainer
	for node, usage := range usagePerNode {
		if strings.HasSuffix(node, "master") {
			masterUsage = usage
		} else {
			nodesUsage = append(nodesUsage, usage)
		}
	}
	nodeAvgUsage := make(ResourceUsagePerContainer)
	for _, nodeUsage := range nodesUsage {
		for c, usage := range nodeUsage {
			if _, found := nodeAvgUsage[c]; !found {
				nodeAvgUsage[c] = &ContainerResourceUsage{Name: usage.Name}
			}
			nodeAvgUsage[c].CPUUsageInCores += usage.CPUUsageInCores
			nodeAvgUsage[c].MemoryUsageInBytes += usage.MemoryUsageInBytes
			nodeAvgUsage[c].MemoryWorkingSetInBytes += usage.MemoryWorkingSetInBytes
			nodeAvgUsage[c].MemoryRSSInBytes += usage.MemoryRSSInBytes
		}
	}
	for c := range nodeAvgUsage {
		nodeAvgUsage[c].CPUUsageInCores /= float64(len(nodesUsage))
		nodeAvgUsage[c].MemoryUsageInBytes /= uint64(len(nodesUsage))
		nodeAvgUsage[c].MemoryWorkingSetInBytes /= uint64(len(nodesUsage))
		nodeAvgUsage[c].MemoryRSSInBytes /= uint64(len(nodesUsage))
	}
	result["master"] = masterUsage
	result["node"] = nodeAvgUsage
	return result
}

// FormatCPUSummary returns the string of human-readable CPU summary from the specified summary data.
func (r *ResourceMonitor) FormatCPUSummary(summary NodesCPUSummary) string {
	// Example output for a node (the percentiles may differ):
	// CPU usage of containers on node "e2e-test-foo-node-0vj7":
	// container        5th%  50th% 90th% 95th%
	// "/"              0.051 0.159 0.387 0.455
	// "/runtime        0.000 0.000 0.146 0.166
	// "/kubelet"       0.036 0.053 0.091 0.154
	// "/misc"          0.001 0.001 0.001 0.002
	var summaryStrings []string
	var header []string
	header = append(header, "container")
	for _, p := range percentiles {
		header = append(header, fmt.Sprintf("%.0fth%%", p*100))
	}
	for nodeName, containers := range summary {
		buf := &bytes.Buffer{}
		w := tabwriter.NewWriter(buf, 1, 0, 1, ' ', 0)
		fmt.Fprintf(w, "%s\n", strings.Join(header, "\t"))
		for _, containerName := range TargetContainers() {
			var s []string
			s = append(s, fmt.Sprintf("%q", containerName))
			data, ok := containers[containerName]
			for _, p := range percentiles {
				value := "N/A"
				if ok {
					value = fmt.Sprintf("%.3f", data[p])
				}
				s = append(s, value)
			}
			fmt.Fprintf(w, "%s\n", strings.Join(s, "\t"))
		}
		w.Flush()
		summaryStrings = append(summaryStrings, fmt.Sprintf("CPU usage of containers on node %q\n:%s", nodeName, buf.String()))
	}
	return strings.Join(summaryStrings, "\n")
}

// LogCPUSummary outputs summary of CPU into log.
func (r *ResourceMonitor) LogCPUSummary() {
	summary := r.GetCPUSummary()
	framework.Logf("%s", r.FormatCPUSummary(summary))
}

// GetCPUSummary returns summary of CPU.
func (r *ResourceMonitor) GetCPUSummary() NodesCPUSummary {
	result := make(NodesCPUSummary)
	for nodeName, collector := range r.collectors {
		result[nodeName] = make(ContainersCPUSummary)
		for _, containerName := range TargetContainers() {
			data := collector.GetBasicCPUStats(containerName)
			result[nodeName][containerName] = data
		}
	}
	return result
}

// GetMasterNodeCPUSummary returns summary of master node CPUs.
func (r *ResourceMonitor) GetMasterNodeCPUSummary(summaryPerNode NodesCPUSummary) NodesCPUSummary {
	result := make(NodesCPUSummary)
	var masterSummary ContainersCPUSummary
	var nodesSummaries []ContainersCPUSummary
	for node, summary := range summaryPerNode {
		if strings.HasSuffix(node, "master") {
			masterSummary = summary
		} else {
			nodesSummaries = append(nodesSummaries, summary)
		}
	}

	nodeAvgSummary := make(ContainersCPUSummary)
	for _, nodeSummary := range nodesSummaries {
		for c, summary := range nodeSummary {
			if _, found := nodeAvgSummary[c]; !found {
				nodeAvgSummary[c] = map[float64]float64{}
			}
			for perc, value := range summary {
				nodeAvgSummary[c][perc] += value
			}
		}
	}
	for c := range nodeAvgSummary {
		for perc := range nodeAvgSummary[c] {
			nodeAvgSummary[c][perc] /= float64(len(nodesSummaries))
		}
	}
	result["master"] = masterSummary
	result["node"] = nodeAvgSummary
	return result
}