apiextension: add metric for openapi regeneration

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/BUILD

@@ -2,7 +2,10 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
-    srcs = ["controller.go"],
+    srcs = [
+        "controller.go",
+        "metrics.go",
+    ],
     importmap = "k8s.io/kubernetes/vendor/k8s.io/apiextensions-apiserver/pkg/controller/openapi",
     importpath = "k8s.io/apiextensions-apiserver/pkg/controller/openapi",
     visibility = ["//visibility:public"],
@@ -17,6 +20,8 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/client-go/tools/cache:go_default_library",
         "//staging/src/k8s.io/client-go/util/workqueue:go_default_library",
+        "//staging/src/k8s.io/component-base/metrics:go_default_library",
+        "//staging/src/k8s.io/component-base/metrics/legacyregistry:go_default_library",
         "//vendor/github.com/go-openapi/spec:go_default_library",
         "//vendor/k8s.io/klog:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/handler:go_default_library",

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

@@ -169,11 +169,12 @@ func (c *Controller) sync(name string) error {
 		}
 		delete(c.crdSpecs, name)
 		klog.V(2).Infof("Updating CRD OpenAPI spec because %s was removed", name)
+		regenerationCounter.With(map[string]string{"crd": name, "reason": "remove"})
 		return c.updateSpecLocked()
 	}
 
 	// compute CRD spec and see whether it changed
-	oldSpecs := c.crdSpecs[crd.Name]
+	oldSpecs, updated := c.crdSpecs[crd.Name]
 	newSpecs, changed, err := buildVersionSpecs(crd, oldSpecs)
 	if err != nil {
 		return err
@@ -185,6 +186,11 @@ func (c *Controller) sync(name string) error {
 	// update specs of this CRD
 	c.crdSpecs[crd.Name] = newSpecs
 	klog.V(2).Infof("Updating CRD OpenAPI spec because %s changed", name)
+	reason := "add"
+	if updated {
+		reason = "update"
+	}
+	regenerationCounter.With(map[string]string{"crd": name, "reason": reason})
 	return c.updateSpecLocked()
 }
 

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

@@ -0,0 +1,37 @@
+/*
+Copyright 2019 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 openapi
+
+import (
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+var (
+	regenerationCounter = metrics.NewCounterVec(
+		&metrics.CounterOpts{
+			Name:           "apiextensions_openapi_v2_regeneration_count",
+			Help:           "Counter of OpenAPI v2 spec regeneration count broken down by causing CRD name and reason.",
+			StabilityLevel: metrics.ALPHA,
+		},
+		[]string{"crd", "reason"},
+	)
+)
+
+func init() {
+	legacyregistry.MustRegister(regenerationCounter)
+}