metrics for CEL compilation and evaluation.

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/compilation.go

@@ -31,6 +31,7 @@ import (
 	apiextensions "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
 	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/library"
+	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/metrics"
 	celmodel "k8s.io/apiextensions-apiserver/third_party/forked/celopenapi/model"
 )
 
@@ -99,6 +100,9 @@ func getBaseEnv() (*cel.Env, error) {
 //  - nil Program, nil Error: The provided rule was empty so compilation was not attempted
 // perCallLimit was added for testing purpose only. Callers should always use const PerCallLimit as input.
 func Compile(s *schema.Structural, isResourceRoot bool, perCallLimit uint64) ([]CompilationResult, error) {
+	t := time.Now()
+	defer metrics.Metrics.ObserveCompilation(time.Since(t))
+
 	if len(s.Extensions.XValidations) == 0 {
 		return nil, nil
 	}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/metrics/metrics.go

@@ -0,0 +1,72 @@
+/*
+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 metrics
+
+import (
+	"time"
+
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+// TODO(jiahuif) CEL is to be used in multiple components, revise naming when that happens.
+const (
+	namespace = "apiserver"
+	subsystem = "cel"
+)
+
+// Metrics provides access to CEL metrics.
+var Metrics = newCelMetrics()
+
+type CelMetrics struct {
+	compilationTime *metrics.Histogram
+	evaluationTime  *metrics.Histogram
+}
+
+func newCelMetrics() *CelMetrics {
+	m := &CelMetrics{
+		compilationTime: metrics.NewHistogram(&metrics.HistogramOpts{
+			Namespace:      namespace,
+			Subsystem:      subsystem,
+			Name:           "compilation_duration_seconds",
+			StabilityLevel: metrics.ALPHA,
+		}),
+		evaluationTime: metrics.NewHistogram(&metrics.HistogramOpts{
+			Namespace:      namespace,
+			Subsystem:      subsystem,
+			Name:           "evaluation_duration_seconds",
+			StabilityLevel: metrics.ALPHA,
+		}),
+	}
+
+	legacyregistry.MustRegister(m.compilationTime)
+	legacyregistry.MustRegister(m.evaluationTime)
+
+	return m
+}
+
+// ObserveCompilation records a CEL compilation with the time the compilation took.
+func (m *CelMetrics) ObserveCompilation(elapsed time.Duration) {
+	seconds := elapsed.Seconds()
+	m.compilationTime.Observe(seconds)
+}
+
+// ObserveEvaluation records a CEL evaluation with the time the evaluation took.
+func (m *CelMetrics) ObserveEvaluation(elapsed time.Duration) {
+	seconds := elapsed.Seconds()
+	m.evaluationTime.Observe(seconds)
+}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/metrics/metrics_test.go

@@ -0,0 +1,68 @@
+/*
+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 metrics
+
+import (
+	"math"
+	"testing"
+	"time"
+
+	"k8s.io/component-base/metrics/legacyregistry"
+)
+
+func TestObserveCompilation(t *testing.T) {
+	defer legacyregistry.Reset()
+	Metrics.ObserveCompilation(2 * time.Second)
+	c, s := gatherHistogram(t, "apiserver_cel_compilation_duration_seconds")
+	if c != 1 {
+		t.Errorf("unexpected count: %v", c)
+	}
+	if math.Abs(s-2.0) > 1e-7 {
+		t.Fatalf("incorrect sum: %v", s)
+	}
+}
+
+func TestObserveEvaluation(t *testing.T) {
+	defer legacyregistry.Reset()
+	Metrics.ObserveEvaluation(2 * time.Second)
+	c, s := gatherHistogram(t, "apiserver_cel_evaluation_duration_seconds")
+	if c != 1 {
+		t.Errorf("unexpected count: %v", c)
+	}
+	if math.Abs(s-2.0) > 1e-7 {
+		t.Fatalf("incorrect sum: %v", s)
+	}
+}
+
+func gatherHistogram(t *testing.T, name string) (count uint64, sum float64) {
+	metrics, err := legacyregistry.DefaultGatherer.Gather()
+	if err != nil {
+		t.Fatalf("Failed to gather metrics: %s", err)
+	}
+	for _, mf := range metrics {
+		if mf.GetName() == name {
+			for _, m := range mf.GetMetric() {
+				h := m.GetHistogram()
+				count += h.GetSampleCount()
+				sum += h.GetSampleSum()
+			}
+			return
+		}
+	}
+	t.Fatalf("metric not found: %v", name)
+	return 0, 0
+}

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/validation.go

@@ -22,6 +22,7 @@ import (
 	"math"
 	"reflect"
 	"strings"
+	"time"
 
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
@@ -29,6 +30,7 @@ import (
 
 	apiextensions "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	"k8s.io/apiextensions-apiserver/pkg/apiserver/schema/cel/metrics"
 	"k8s.io/apiextensions-apiserver/third_party/forked/celopenapi/model"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 )
@@ -113,6 +115,8 @@ func validator(s *schema.Structural, isResourceRoot bool, perCallLimit uint64) *
 // Most callers can ignore the returned remainingBudget value unless another validate call is going to be made
 // context is passed for supporting context cancellation during cel validation
 func (s *Validator) Validate(ctx context.Context, fldPath *field.Path, sts *schema.Structural, obj, oldObj interface{}, costBudget int64) (errs field.ErrorList, remainingBudget int64) {
+	t := time.Now()
+	defer metrics.Metrics.ObserveEvaluation(time.Since(t))
 	remainingBudget = costBudget
 	if s == nil || obj == nil {
 		return nil, remainingBudget