Stop create hidden metrics for custom metrics

Author: RainbowMango

staging/src/k8s.io/component-base/metrics/collector.go

@@ -18,7 +18,6 @@ package metrics
 
 import (
 	"fmt"
-	"strings"
 
 	"github.com/blang/semver"
 	"github.com/prometheus/client_golang/prometheus"
@@ -46,7 +45,6 @@ type StableCollector interface {
 type BaseStableCollector struct {
 	descriptors []*Desc // stores all Desc collected from DescribeWithStability().
 	registrable []*Desc // stores registrable Desc(not be hidden), is a subset of descriptors.
-	hidden      []*Desc // stores hidden Desc
 	self        StableCollector
 }
 
@@ -59,7 +57,7 @@ func (bsc *BaseStableCollector) DescribeWithStability(ch chan<- *Desc) {
 // Describe sends all descriptors to the provided channel.
 // It intend to be called by prometheus registry.
 func (bsc *BaseStableCollector) Describe(ch chan<- *prometheus.Desc) {
-	for _, d := range bsc.descriptors {
+	for _, d := range bsc.registrable {
 		ch <- d.toPrometheusDesc()
 	}
 }
@@ -80,10 +78,8 @@ func (bsc *BaseStableCollector) Collect(ch chan<- prometheus.Metric) {
 	}()
 
 	for m := range mch {
-		// Hidden metrics should be ignored.
-		// TODO(RainbowMango): There is no convenient method to identify if the metrics should be ignored.
-		// 	Use a temporary solution here. (try to search in hidden list)
-		if strings.Contains(m.Desc().String(), hiddenFlag) {
+		// nil Metric usually means hidden metrics
+		if m == nil {
 			continue
 		}
 
@@ -127,16 +123,16 @@ func (bsc *BaseStableCollector) Create(version *semver.Version, self StableColle
 			d.createLock.Lock()
 			defer d.createLock.Unlock()
 
-			d.isCreated = true
-			if d.IsHidden() { // hidden metrics also needs initialize because user may send them in CollectWithStability method.
-				d.initializeHiddenDesc()
-				bsc.hidden = append(bsc.hidden, d)
+			if d.IsHidden() {
+				// do nothing for hidden metrics
 			} else if d.IsDeprecated() {
 				d.initializeDeprecatedDesc()
 				bsc.registrable = append(bsc.registrable, d)
+				d.isCreated = true
 			} else {
 				d.initialize()
 				bsc.registrable = append(bsc.registrable, d)
+				d.isCreated = true
 			}
 		})
 	}

staging/src/k8s.io/component-base/metrics/collector_test.go

@@ -52,25 +52,25 @@ func (tc *testCustomCollector) DescribeWithStability(ch chan<- *Desc) {
 }
 
 func (tc *testCustomCollector) CollectWithStability(ch chan<- Metric) {
-	ch <- MustNewConstMetric(
+	ch <- NewLazyConstMetric(
 		alphaDesc,
 		GaugeValue,
 		1,
 		"value",
 	)
-	ch <- MustNewConstMetric(
+	ch <- NewLazyConstMetric(
 		stableDesc,
 		GaugeValue,
 		1,
 		"value",
 	)
-	ch <- MustNewConstMetric(
+	ch <- NewLazyConstMetric(
 		deprecatedDesc,
 		GaugeValue,
 		1,
 		"value",
 	)
-	ch <- MustNewConstMetric(
+	ch <- NewLazyConstMetric(
 		hiddenDesc,
 		GaugeValue,
 		1,

staging/src/k8s.io/component-base/metrics/desc.go

@@ -26,8 +26,6 @@ import (
 	"k8s.io/klog"
 )
 
-var hiddenFlag = "metricsshouldbehidden"
-
 // Desc is a prometheus.Desc extension.
 //
 // Use NewDesc to create new Desc instances.
@@ -72,20 +70,14 @@ type Desc struct {
 func NewDesc(fqName string, help string, variableLabels []string, constLabels Labels,
 	stabilityLevel StabilityLevel, deprecatedVersion string) *Desc {
 	d := &Desc{
-		fqName:         fqName,
-		help:           help,
-		variableLabels: variableLabels,
-		constLabels:    constLabels,
-	}
-
-	// TODO(RainbowMango): replace by stabilityLevel.setDefault() after PR(https://github.com/kubernetes/kubernetes/pull/82957) be merged.
-	if stabilityLevel == "" {
-		d.stabilityLevel = ALPHA
-	} else {
-		d.stabilityLevel = stabilityLevel
+		fqName:            fqName,
+		help:              help,
+		variableLabels:    variableLabels,
+		constLabels:       constLabels,
+		stabilityLevel:    stabilityLevel,
+		deprecatedVersion: deprecatedVersion,
 	}
-
-	d.deprecatedVersion = deprecatedVersion
+	d.stabilityLevel.setDefaults()
 
 	return d
 }
@@ -148,14 +140,6 @@ func (d *Desc) markDeprecated() {
 	})
 }
 
-// markHidden mark a special flag to 'HELP'.
-// The metrics marked with this flag will be ignored when collecting automatically.
-func (d *Desc) markHidden() {
-	d.hideOnce.Do(func() {
-		d.help = fmt.Sprintf("(%s) %s", hiddenFlag, d.help)
-	})
-}
-
 func (d *Desc) annotateStabilityLevel() {
 	d.annotateOnce.Do(func() {
 		d.help = fmt.Sprintf("[%v] %v", d.stabilityLevel, d.help)
@@ -172,8 +156,3 @@ func (d *Desc) initializeDeprecatedDesc() {
 	d.markDeprecated()
 	d.initialize()
 }
-
-func (d *Desc) initializeHiddenDesc() {
-	d.markHidden()
-	d.initializeDeprecatedDesc()
-}

staging/src/k8s.io/component-base/metrics/value.go

@@ -16,7 +16,9 @@ limitations under the License.
 
 package metrics
 
-import "github.com/prometheus/client_golang/prometheus"
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
 
 // ValueType is an enumeration of metric types that represent a simple value.
 type ValueType int
@@ -33,7 +35,12 @@ func (vt *ValueType) toPromValueType() prometheus.ValueType {
 	return prometheus.ValueType(*vt)
 }
 
-// MustNewConstMetric is a wrapper of prometheus.MustNewConstMetric
-func MustNewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues ...string) Metric {
+// NewLazyConstMetric is a helper of MustNewConstMetric.
+//
+// Note: If the metrics described by the desc is hidden, the metrics will not be created.
+func NewLazyConstMetric(desc *Desc, valueType ValueType, value float64, labelValues ...string) Metric {
+	if desc.IsHidden() {
+		return nil
+	}
 	return prometheus.MustNewConstMetric(desc.toPrometheusDesc(), valueType.toPromValueType(), value, labelValues...)
 }