Refactor kubelet metricsets to share response from endpoint

Signed-off-by: chrismark <chrismarkou92@gmail.com>

metricbeat/module/kubernetes/kubernetes.go

@@ -18,6 +18,7 @@
 package kubernetes
 
 import (
+	"github.com/elastic/beats/v7/metricbeat/helper"
 	"sync"
 	"time"
 
@@ -39,6 +40,7 @@ func init() {
 type Module interface {
 	mb.Module
 	GetSharedFamilies(prometheus p.Prometheus) ([]*dto.MetricFamily, error)
+	GetSharedKubeletStats(http *helper.HTTP) ([]byte, error)
 }
 
 type familiesCache struct {
@@ -61,30 +63,51 @@ func (c *kubeStateMetricsCache) getCacheMapEntry(hash uint64) *familiesCache {
 	return c.cacheMap[hash]
 }
 
+type statsCache struct {
+	sharedStats        []byte
+	lastFetchErr       error
+	lastFetchTimestamp time.Time
+}
+
+type kubeletStatsCache struct {
+	cacheMap map[uint64]*statsCache
+	lock     sync.Mutex
+}
+
+func (c *kubeletStatsCache) getCacheMapEntry(hash uint64) *statsCache {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	if _, ok := c.cacheMap[hash]; !ok {
+		c.cacheMap[hash] = &statsCache{}
+	}
+	return c.cacheMap[hash]
+}
+
 type module struct {
 	mb.BaseModule
 
 	kubeStateMetricsCache *kubeStateMetricsCache
-	familiesCache         *familiesCache
+	kubeletStatsCache *kubeletStatsCache
+	cacheHash uint64
 }
 
 func ModuleBuilder() func(base mb.BaseModule) (mb.Module, error) {
 	kubeStateMetricsCache := &kubeStateMetricsCache{
 		cacheMap: make(map[uint64]*familiesCache),
 	}
+	kubeletStatsCache := &kubeletStatsCache{
+		cacheMap: make(map[uint64]*statsCache),
+	}
 	return func(base mb.BaseModule) (mb.Module, error) {
 		hash, err := generateCacheHash(base.Config().Hosts)
 		if err != nil {
 			return nil, errors.Wrap(err, "error generating cache hash for kubeStateMetricsCache")
 		}
-		// NOTE: These entries will be never removed, this can be a leak if
-		// metricbeat is used to monitor clusters dynamically created.
-		// (https://github.com/elastic/beats/pull/25640#discussion_r633395213)
-		familiesCache := kubeStateMetricsCache.getCacheMapEntry(hash)
 		m := module{
 			BaseModule:            base,
 			kubeStateMetricsCache: kubeStateMetricsCache,
-			familiesCache:         familiesCache,
+			kubeletStatsCache: kubeletStatsCache,
+			cacheHash: hash,
 		}
 		return &m, nil
 	}
@@ -96,12 +119,36 @@ func (m *module) GetSharedFamilies(prometheus p.Prometheus) ([]*dto.MetricFamily
 
 	now := time.Now()
 
-	if m.familiesCache.lastFetchTimestamp.IsZero() || now.Sub(m.familiesCache.lastFetchTimestamp) > m.Config().Period {
-		m.familiesCache.sharedFamilies, m.familiesCache.lastFetchErr = prometheus.GetFamilies()
-		m.familiesCache.lastFetchTimestamp = now
+	// NOTE: These entries will be never removed, this can be a leak if
+	// metricbeat is used to monitor clusters dynamically created.
+	// (https://github.com/elastic/beats/pull/25640#discussion_r633395213)
+	familiesCache := m.kubeStateMetricsCache.getCacheMapEntry(m.cacheHash)
+
+	if familiesCache.lastFetchTimestamp.IsZero() || now.Sub(familiesCache.lastFetchTimestamp) > m.Config().Period {
+		familiesCache.sharedFamilies, familiesCache.lastFetchErr = prometheus.GetFamilies()
+		familiesCache.lastFetchTimestamp = now
+	}
+
+	return familiesCache.sharedFamilies, familiesCache.lastFetchErr
+}
+
+func (m *module) GetSharedKubeletStats(http *helper.HTTP) ([]byte, error) {
+	m.kubeletStatsCache.lock.Lock()
+	defer m.kubeletStatsCache.lock.Unlock()
+
+	now := time.Now()
+
+	// NOTE: These entries will be never removed, this can be a leak if
+	// metricbeat is used to monitor clusters dynamically created.
+	// (https://github.com/elastic/beats/pull/25640#discussion_r633395213)
+	statsCache := m.kubeletStatsCache.getCacheMapEntry(m.cacheHash)
+
+	if statsCache.lastFetchTimestamp.IsZero() || now.Sub(statsCache.lastFetchTimestamp) > m.Config().Period {
+		statsCache.sharedStats, statsCache.lastFetchErr = http.FetchContent()
+		statsCache.lastFetchTimestamp = now
 	}
 
-	return m.familiesCache.sharedFamilies, m.familiesCache.lastFetchErr
+	return statsCache.sharedStats, statsCache.lastFetchErr
 }
 
 func generateCacheHash(host []string) (uint64, error) {

metricbeat/module/kubernetes/node/node.go

@@ -18,6 +18,7 @@
 package node
 
 import (
+	"fmt"
 	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/v7/libbeat/common"
@@ -26,6 +27,7 @@ import (
 	"github.com/elastic/beats/v7/metricbeat/helper"
 	"github.com/elastic/beats/v7/metricbeat/mb"
 	"github.com/elastic/beats/v7/metricbeat/mb/parse"
+	k8smod "github.com/elastic/beats/v7/metricbeat/module/kubernetes"
 	"github.com/elastic/beats/v7/metricbeat/module/kubernetes/util"
 )
 
@@ -60,6 +62,7 @@ type MetricSet struct {
 	mb.BaseMetricSet
 	http     *helper.HTTP
 	enricher util.Enricher
+	mod        k8smod.Module
 }
 
 // New create a new instance of the MetricSet
@@ -70,11 +73,15 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	if err != nil {
 		return nil, err
 	}
-
+	mod, ok := base.Module().(k8smod.Module)
+	if !ok {
+		return nil, fmt.Errorf("must be child of kubernetes module")
+	}
 	return &MetricSet{
 		BaseMetricSet: base,
 		http:          http,
 		enricher:      util.NewResourceMetadataEnricher(base, &kubernetes.Node{}, false),
+		mod: mod,
 	}, nil
 }
 
@@ -84,7 +91,7 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
 	m.enricher.Start()
 
-	body, err := m.http.FetchContent()
+	body, err := m.mod.GetSharedKubeletStats(m.http)
 	if err != nil {
 		return errors.Wrap(err, "error doing HTTP request to fetch 'node' Metricset data")
 

metricbeat/module/kubernetes/pod/pod.go

@@ -18,13 +18,15 @@
 package pod
 
 import (
+	"fmt"
 	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/v7/libbeat/common/kubernetes"
 	"github.com/elastic/beats/v7/libbeat/logp"
 	"github.com/elastic/beats/v7/metricbeat/helper"
 	"github.com/elastic/beats/v7/metricbeat/mb"
 	"github.com/elastic/beats/v7/metricbeat/mb/parse"
+	k8smod "github.com/elastic/beats/v7/metricbeat/module/kubernetes"
 	"github.com/elastic/beats/v7/metricbeat/module/kubernetes/util"
 )
 
@@ -59,6 +61,7 @@ type MetricSet struct {
 	mb.BaseMetricSet
 	http     *helper.HTTP
 	enricher util.Enricher
+	mod        k8smod.Module
 }
 
 // New create a new instance of the MetricSet
@@ -69,11 +72,15 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	if err != nil {
 		return nil, err
 	}
-
+	mod, ok := base.Module().(k8smod.Module)
+	if !ok {
+		return nil, fmt.Errorf("must be child of kubernetes module")
+	}
 	return &MetricSet{
 		BaseMetricSet: base,
 		http:          http,
 		enricher:      util.NewResourceMetadataEnricher(base, &kubernetes.Pod{}, true),
+		mod: mod,
 	}, nil
 }
 
@@ -83,9 +90,9 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
 	m.enricher.Start()
 
-	body, err := m.http.FetchContent()
+	body, err := m.mod.GetSharedKubeletStats(m.http)
 	if err != nil {
-		return errors.Wrap(err, "error doing HTTP request to fetch 'pod' Metricset data")
+		return errors.Wrap(err, "error fetching shared data for 'pod' Metricset")
 	}
 
 	events, err := eventMapping(body, util.PerfMetrics)

metricbeat/module/kubernetes/system/system.go

@@ -18,12 +18,14 @@
 package system
 
 import (
+	"fmt"
 	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/v7/libbeat/logp"
 	"github.com/elastic/beats/v7/metricbeat/helper"
 	"github.com/elastic/beats/v7/metricbeat/mb"
 	"github.com/elastic/beats/v7/metricbeat/mb/parse"
+	k8smod "github.com/elastic/beats/v7/metricbeat/module/kubernetes"
 )
 
 const (
@@ -56,6 +58,7 @@ func init() {
 type MetricSet struct {
 	mb.BaseMetricSet
 	http *helper.HTTP
+	mod        k8smod.Module
 }
 
 // New create a new instance of the MetricSet
@@ -66,17 +69,22 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	if err != nil {
 		return nil, err
 	}
+	mod, ok := base.Module().(k8smod.Module)
+	if !ok {
+		return nil, fmt.Errorf("must be child of kubernetes module")
+	}
 	return &MetricSet{
 		BaseMetricSet: base,
 		http:          http,
+		mod: mod,
 	}, nil
 }
 
 // Fetch methods implements the data gathering and data conversion to the right
 // format. It publishes the event which is then forwarded to the output. In case
 // of an error set the Error field of mb.Event or simply call report.Error().
 func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
-	body, err := m.http.FetchContent()
+	body, err := m.mod.GetSharedKubeletStats(m.http)
 	if err != nil {
 		return errors.Wrap(err, "error doing HTTP request to fetch 'system' Metricset data")
 	}

metricbeat/module/kubernetes/volume/volume.go

@@ -18,12 +18,14 @@
 package volume
 
 import (
+	"fmt"
 	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/v7/libbeat/logp"
 	"github.com/elastic/beats/v7/metricbeat/helper"
 	"github.com/elastic/beats/v7/metricbeat/mb"
 	"github.com/elastic/beats/v7/metricbeat/mb/parse"
+	k8smod "github.com/elastic/beats/v7/metricbeat/module/kubernetes"
 )
 
 const (
@@ -56,6 +58,7 @@ func init() {
 type MetricSet struct {
 	mb.BaseMetricSet
 	http *helper.HTTP
+	mod        k8smod.Module
 }
 
 // New create a new instance of the MetricSet
@@ -66,17 +69,22 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	if err != nil {
 		return nil, err
 	}
+	mod, ok := base.Module().(k8smod.Module)
+	if !ok {
+		return nil, fmt.Errorf("must be child of kubernetes module")
+	}
 	return &MetricSet{
 		BaseMetricSet: base,
 		http:          http,
+		mod: mod,
 	}, nil
 }
 
 // Fetch methods implements the data gathering and data conversion to the right
 // format. It publishes the event which is then forwarded to the output. In case
 // of an error set the Error field of mb.Event or simply call report.Error().
 func (m *MetricSet) Fetch(reporter mb.ReporterV2) error {
-	body, err := m.http.FetchContent()
+	body, err := m.mod.GetSharedKubeletStats(m.http)
 	if err != nil {
 		return errors.Wrap(err, "error doing HTTP request to fetch 'volume' Metricset data")
 	}