Add metrics for OpenAPI v3 generation

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapiv3/controller.go

@@ -178,6 +178,7 @@ func (c *Controller) deleteCRD(name string) {
 			if len(crdListForGV) == 0 {
 				delete(c.specsByGVandName, gv)
 			}
+			regenerationCounter.With(map[string]string{"group": gv.Group, "version": gv.Version, "crd": name, "reason": "remove"})
 			c.updateGroupVersion(gv)
 		}
 	}
@@ -210,7 +211,9 @@ func (c *Controller) updateCRDSpec(crd *apiextensionsv1.CustomResourceDefinition
 	}
 
 	_, ok := c.specsByGVandName[gv]
+	reason := "update"
 	if !ok {
+		reason = "add"
 		c.specsByGVandName[gv] = map[string]*spec3.OpenAPI{}
 	}
 
@@ -222,7 +225,7 @@ func (c *Controller) updateCRDSpec(crd *apiextensionsv1.CustomResourceDefinition
 		}
 	}
 	c.specsByGVandName[gv][name] = v3
-
+	regenerationCounter.With(map[string]string{"crd": name, "group": gv.Group, "version": gv.Version, "reason": reason})
 	return c.updateGroupVersion(gv)
 }
 

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapiv3/metrics.go

@@ -0,0 +1,37 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package openapiv3
+
+import (
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+var (
+	regenerationCounter = metrics.NewCounterVec(
+		&metrics.CounterOpts{
+			Name:           "apiextensions_openapi_v3_regeneration_count",
+			Help:           "Counter of OpenAPI v3 spec regeneration count broken down by group, version, causing CRD and reason.",
+			StabilityLevel: metrics.ALPHA,
+		},
+		[]string{"group", "version", "crd", "reason"},
+	)
+)
+
+func init() {
+	legacyregistry.MustRegister(regenerationCounter)
+}