From 334a5aeda5e654586b61a22da2592da9fb601643 Mon Sep 17 00:00:00 2001
From: Han Kang <hankang@google.com>
Date: Thu, 20 Jun 2019 11:43:29 -0700
Subject: [PATCH] enable ability to show hidden metrics

---
 .../k8s.io/component-base/metrics/metric.go   |  4 ++
 .../k8s.io/component-base/metrics/registry.go | 24 +++++++++++
 .../component-base/metrics/registry_test.go   | 41 ++++++++++++++++++-
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/staging/src/k8s.io/component-base/metrics/metric.go b/staging/src/k8s.io/component-base/metrics/metric.go
index 0d2eca5ac86..2c213db879c 100644
--- a/staging/src/k8s.io/component-base/metrics/metric.go
+++ b/staging/src/k8s.io/component-base/metrics/metric.go
@@ -92,6 +92,10 @@ func (r *lazyMetric) determineDeprecationStatus(version semver.Version) {
 		if selfVersion.LTE(version) {
 			r.isDeprecated = true
 		}
+		if ShouldShowHidden() {
+			klog.Warningf("Hidden metrics have been manually overridden, showing this very deprecated metric.")
+			return
+		}
 		if selfVersion.LT(version) {
 			klog.Warningf("This metric has been deprecated for more than one release, hiding.")
 			r.isHidden = true
diff --git a/staging/src/k8s.io/component-base/metrics/registry.go b/staging/src/k8s.io/component-base/metrics/registry.go
index 42615df3099..237ef69c92f 100644
--- a/staging/src/k8s.io/component-base/metrics/registry.go
+++ b/staging/src/k8s.io/component-base/metrics/registry.go
@@ -17,12 +17,36 @@ limitations under the License.
 package metrics
 
 import (
+	"sync"
+	"sync/atomic"
+
 	"github.com/blang/semver"
 	"github.com/prometheus/client_golang/prometheus"
 	dto "github.com/prometheus/client_model/go"
+
 	apimachineryversion "k8s.io/apimachinery/pkg/version"
 )
 
+var (
+	showHiddenOnce sync.Once
+	showHidden     atomic.Value
+)
+
+// SetShowHidden will enable showing hidden metrics. This will no-opt
+// after the initial call
+func SetShowHidden() {
+	showHiddenOnce.Do(func() {
+		showHidden.Store(true)
+	})
+}
+
+// ShouldShowHidden returns whether showing hidden deprecated metrics
+// is enabled. While the primary usecase for this is internal (to determine
+// registration behavior) this can also be used to introspect
+func ShouldShowHidden() bool {
+	return showHidden.Load() != nil && showHidden.Load().(bool)
+}
+
 // Registerable is an interface for a collector metric which we
 // will register with KubeRegistry.
 type Registerable interface {
diff --git a/staging/src/k8s.io/component-base/metrics/registry_test.go b/staging/src/k8s.io/component-base/metrics/registry_test.go
index 30ad55b528f..612f34385d8 100644
--- a/staging/src/k8s.io/component-base/metrics/registry_test.go
+++ b/staging/src/k8s.io/component-base/metrics/registry_test.go
@@ -17,11 +17,12 @@ limitations under the License.
 package metrics
 
 import (
+	"testing"
+
 	"github.com/blang/semver"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/assert"
 	apimachineryversion "k8s.io/apimachinery/pkg/version"
-	"testing"
 )
 
 var (
@@ -195,4 +196,42 @@ func TestMustRegister(t *testing.T) {
 			}
 		})
 	}
+
+}
+func TestShowHiddenMetric(t *testing.T) {
+	registry := NewKubeRegistry(apimachineryversion.Info{
+		Major:      "1",
+		Minor:      "15",
+		GitVersion: "v1.15.0-alpha-1.12345",
+	})
+
+	expectedMetricCount := 0
+	registry.MustRegister(alphaHiddenCounter)
+
+	ms, err := registry.Gather()
+	if len(ms) != expectedMetricCount {
+		t.Errorf("Got %v metrics, Want: %v metrics", len(ms), expectedMetricCount)
+	}
+	showHidden.Store(true)
+	defer showHidden.Store(false)
+	registry.MustRegister(NewCounter(
+		&CounterOpts{
+			Namespace:         "some_namespace",
+			Name:              "test_alpha_show_hidden_counter",
+			Subsystem:         "subsystem",
+			StabilityLevel:    ALPHA,
+			Help:              "counter help",
+			DeprecatedVersion: &v114,
+		},
+	))
+	expectedMetricCount = 1
+
+	ms, err = registry.Gather()
+	if len(ms) != expectedMetricCount {
+		t.Errorf("Got %v metrics, Want: %v metrics", len(ms), expectedMetricCount)
+	}
+	if err != nil {
+		t.Fatalf("Gather failed %v", err)
+	}
+
 }