Merge pull request #78773 from logicalhan/base-registry

preload metrics for legacyregistry for backwards compatibility

staging/src/k8s.io/component-base/metrics/legacyregistry/BUILD

@@ -10,6 +10,7 @@ go_library(
     deps = [
         "//staging/src/k8s.io/apimachinery/pkg/version:go_default_library",
         "//staging/src/k8s.io/component-base/metrics:go_default_library",
+        "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
     ],
 )
 

staging/src/k8s.io/component-base/metrics/legacyregistry/registry.go

@@ -18,9 +18,11 @@ package legacyregistry
 
 import (
 	"fmt"
+	"sync"
+
+	"github.com/prometheus/client_golang/prometheus"
 	apimachineryversion "k8s.io/apimachinery/pkg/version"
 	"k8s.io/component-base/metrics"
-	"sync"
 )
 
 var globalRegistryFactory = metricsRegistryFactory{
@@ -51,7 +53,11 @@ func SetRegistryFactoryVersion(ver apimachineryversion.Info) []error {
 		return nil
 	}
 	registrationErrs := make([]error, 0)
-	globalRegistryFactory.globalRegistry = metrics.NewKubeRegistry(ver)
+	preloadedMetrics := []prometheus.Collector{
+		prometheus.NewGoCollector(),
+		prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}),
+	}
+	globalRegistryFactory.globalRegistry = metrics.NewPreloadedKubeRegistry(ver, preloadedMetrics...)
 	globalRegistryFactory.kubeVersion = &ver
 	for _, c := range globalRegistryFactory.registerQueue {
 		err := globalRegistryFactory.globalRegistry.Register(c)

staging/src/k8s.io/component-base/metrics/legacyregistry/registry_test.go

@@ -193,3 +193,33 @@ func TestDeferredMustRegister(t *testing.T) {
 		},
 		"Did not panic even though we expected it.")
 }
+
+func TestPreloadedMetrics(t *testing.T) {
+	// reset the global registry for this test.
+	globalRegistryFactory = metricsRegistryFactory{
+		registerQueue:     make([]metrics.KubeCollector, 0),
+		mustRegisterQueue: make([]metrics.KubeCollector, 0),
+	}
+
+	SetRegistryFactoryVersion(apimachineryversion.Info{
+		Major:      "1",
+		Minor:      "15",
+		GitVersion: "v1.15.0-alpha-1.12345",
+	})
+	// partial list of some preregistered metrics we expect
+	expectedMetricNames := []string{"go_gc_duration_seconds", "process_start_time_seconds"}
+
+	mf, err := globalRegistryFactory.globalRegistry.Gather()
+	if err != nil {
+		t.Errorf("Got unexpected error %v ", err)
+	}
+	metricNames := map[string]struct{}{}
+	for _, f := range mf {
+		metricNames[f.GetName()] = struct{}{}
+	}
+	for _, expectedMetric := range expectedMetricNames {
+		if _, ok := metricNames[expectedMetric]; !ok {
+			t.Errorf("Expected %v to be preregistered", expectedMetric)
+		}
+	}
+}

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

@@ -94,3 +94,18 @@ func NewKubeRegistry(v apimachineryversion.Info) KubeRegistry {
 		version:      parseVersion(v),
 	}
 }
+
+// NewPreloadedKubeRegistry creates a new Registry with preloaded prometheus collectors
+// already registered. This is exposed specifically to maintain backwards
+// compatibility with the global prometheus registry.
+//
+// Deprecated
+func NewPreloadedKubeRegistry(v apimachineryversion.Info, cs ...prometheus.Collector) KubeRegistry {
+	registry := &kubeRegistry{
+		PromRegistry: prometheus.NewRegistry(),
+		version:      parseVersion(v),
+	}
+
+	registry.PromRegistry.MustRegister(cs...)
+	return registry
+}