metrics: promote apiserver_storage_object_counts to stable

- rename etcd_object_counts to apiserver_storage_object_counts

CONTEXT https://github.com/kubernetes/kubernetes/issues/98270
FIXES https://github.com/kubernetes/kubernetes/issues/98270

staging/src/k8s.io/apiserver/pkg/storage/etcd3/metrics/metrics.go

@@ -43,11 +43,20 @@ var (
 		},
 		[]string{"operation", "type"},
 	)
+	etcdObjectCounts = compbasemetrics.NewGaugeVec(
+		&compbasemetrics.GaugeOpts{
+			Name:              "etcd_object_counts",
+			DeprecatedVersion: "1.21.0",
+			Help:              "Number of stored objects at the time of last check split by kind. This metric is replaced by apiserver_storage_object_counts.",
+			StabilityLevel:    compbasemetrics.ALPHA,
+		},
+		[]string{"resource"},
+	)
 	objectCounts = compbasemetrics.NewGaugeVec(
 		&compbasemetrics.GaugeOpts{
-			Name:           "etcd_object_counts",
+			Name:           "apiserver_storage_object_counts",
 			Help:           "Number of stored objects at the time of last check split by kind.",
-			StabilityLevel: compbasemetrics.ALPHA,
+			StabilityLevel: compbasemetrics.STABLE,
 		},
 		[]string{"resource"},
 	)
@@ -86,15 +95,17 @@ func Register() {
 	registerMetrics.Do(func() {
 		legacyregistry.MustRegister(etcdRequestLatency)
 		legacyregistry.MustRegister(objectCounts)
+		legacyregistry.MustRegister(etcdObjectCounts)
 		legacyregistry.MustRegister(dbTotalSize)
 		legacyregistry.MustRegister(etcdBookmarkCounts)
 		legacyregistry.MustRegister(etcdLeaseObjectCounts)
 	})
 }
 
-// UpdateObjectCount sets the etcd_object_counts metric.
+// UpdateObjectCount sets the apiserver_storage_object_counts and etcd_object_counts (deprecated) metric.
 func UpdateObjectCount(resourcePrefix string, count int64) {
 	objectCounts.WithLabelValues(resourcePrefix).Set(float64(count))
+	etcdObjectCounts.WithLabelValues(resourcePrefix).Set(float64(count))
 }
 
 // RecordEtcdRequestLatency sets the etcd_request_duration_seconds metrics.

test/instrumentation/testdata/stable-metrics-list.yaml

@@ -65,3 +65,9 @@
   - subresource
   - verb
   - version
+- name: apiserver_storage_object_counts
+  help: Number of stored objects at the time of last check split by kind.
+  type: Gauge
+  stabilityLevel: STABLE
+  labels:
+  - resource