cronjob_controller: add metrics for job creation skew duration

pkg/controller/cronjob/cronjob_controllerv2.go

@@ -46,6 +46,7 @@ import (
 	"k8s.io/component-base/metrics/prometheus/ratelimiter"
 	"k8s.io/klog/v2"
 	"k8s.io/kubernetes/pkg/controller"
+	"k8s.io/kubernetes/pkg/controller/cronjob/metrics"
 )
 
 var (
@@ -114,6 +115,8 @@ func NewControllerV2(jobInformer batchv1informers.JobInformer, cronJobsInformer
 		},
 	})
 
+	metrics.Register()
+
 	return jm, nil
 }
 
@@ -570,6 +573,7 @@ func (jm *ControllerV2) syncCronJob(
 		return cj, nil, err
 	}
 
+	metrics.CronJobCreationSkew.Observe(jobResp.ObjectMeta.GetCreationTimestamp().Sub(*scheduledTime).Seconds())
 	klog.V(4).InfoS("Created Job", "job", klog.KRef(jobResp.GetNamespace(), jobResp.GetName()), "cronjob", klog.KRef(cj.GetNamespace(), cj.GetName()))
 	jm.recorder.Eventf(cj, corev1.EventTypeNormal, "SuccessfulCreate", "Created job %v", jobResp.Name)
 

pkg/controller/cronjob/metrics/metrics.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2021 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 metrics
+
+import (
+	"sync"
+
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+const CronJobControllerSubsystem = "cronjob_controller"
+
+var (
+	CronJobCreationSkew = metrics.NewHistogram(
+		&metrics.HistogramOpts{
+			Subsystem:      CronJobControllerSubsystem,
+			Name:           "cronjob_job_creation_skew_duration_seconds",
+			Help:           "Time between when a cronjob is scheduled to be run, and when the corresponding job is created",
+			StabilityLevel: metrics.ALPHA,
+			Buckets:        metrics.ExponentialBuckets(1, 2, 10),
+		},
+	)
+)
+
+var registerMetrics sync.Once
+
+// Register registers CronjobController metrics.
+func Register() {
+	registerMetrics.Do(func() {
+		legacyregistry.MustRegister(CronJobCreationSkew)
+	})
+}