add metrics instrumentation for status updater

Signed-off-by: shawnh2 <shawnhxh@outlook.com>

internal/metrics/options.go

@@ -5,7 +5,7 @@
 
 package metrics
 
-// Options encode changes to the options passed to a Metric at creation time.
+// MetricOption encode changes to the options passed to a Metric at creation time.
 type MetricOption func(*MetricOptions)
 
 type MetricOptions struct {

internal/provider/kubernetes/metrics.go

@@ -0,0 +1,20 @@
+// Copyright Envoy Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package kubernetes
+
+import "github.com/envoyproxy/gateway/internal/metrics"
+
+var (
+	statusUpdateTotal           = metrics.NewCounter("status_update_total", "Total number of status updates by object kind.")
+	statusUpdateFailed          = metrics.NewCounter("status_update_failed_total", "Number of status updates that failed by object kind.")
+	statusUpdateConflict        = metrics.NewCounter("status_update_conflict_total", "Number of status update conflicts encountered by object kind.")
+	statusUpdateNotFound        = metrics.NewCounter("status_update_not_found_total", "Number of status update that not found by object kind.")
+	statusUpdateSuccess         = metrics.NewCounter("status_update_success_total", "Number of status updates that succeeded by object kind.")
+	statusUpdateNoop            = metrics.NewCounter("status_update_noop_total", "Number of status updates that are no-ops by object kind. This is a subset of successful status updates.")
+	statusUpdateDurationSeconds = metrics.NewHistogram("status_update_duration_seconds", "How long a status update takes to finish.", []float64{0.001, 0.01, 0.1, 1, 5, 10})
+
+	kindLabel = metrics.NewLabel("kind")
+)

internal/provider/kubernetes/status_updater.go

@@ -7,6 +7,7 @@ package kubernetes
 
 import (
 	"context"
+	"time"
 
 	"github.com/go-logr/logr"
 	"github.com/google/go-cmp/cmp"
@@ -66,31 +67,62 @@ func NewUpdateHandler(log logr.Logger, client client.Client) *UpdateHandler {
 }
 
 func (u *UpdateHandler) apply(update Update) {
-	if err := retry.RetryOnConflict(retry.DefaultBackoff, func() error {
-		obj := update.Resource
+	var (
+		statusUpdateErr error
 
+		startTime = time.Now()
+		obj       = update.Resource
+		objKind   = obj.GetObjectKind().GroupVersionKind().Kind
+	)
+
+	statusUpdateTotal.With(kindLabel.Value(objKind)).Increment()
+
+	defer func() {
+		updateDuration := time.Since(startTime)
+		statusUpdateDurationSeconds.With(kindLabel.Value(objKind)).Record(updateDuration.Seconds())
+
+		if statusUpdateErr != nil {
+			statusUpdateFailed.With(kindLabel.Value(objKind)).Increment()
+		} else {
+			statusUpdateSuccess.With(kindLabel.Value(objKind)).Increment()
+		}
+	}()
+
+	if statusUpdateErr = retry.OnError(retry.DefaultBackoff, func(err error) bool {
+		if kerrors.IsConflict(err) {
+			statusUpdateConflict.With(kindLabel.Value(objKind)).Increment()
+			return true
+		}
+
+		if kerrors.IsNotFound(err) {
+			statusUpdateNotFound.With(kindLabel.Value(objKind)).Increment()
+			return true
+		}
+
+		return false
+	}, func() error {
 		// Get the resource.
 		if err := u.client.Get(context.Background(), update.NamespacedName, obj); err != nil {
-			if kerrors.IsNotFound(err) {
-				return nil
-			}
 			return err
 		}
 
 		newObj := update.Mutator.Mutate(obj)
 
 		if isStatusEqual(obj, newObj) {
+			statusUpdateNoop.With(kindLabel.Value(objKind)).Increment()
+
 			u.log.WithName(update.NamespacedName.Name).
 				WithName(update.NamespacedName.Namespace).
 				Info("status unchanged, bypassing update")
+
 			return nil
 		}
 
 		newObj.SetUID(obj.GetUID())
 
 		return u.client.Status().Update(context.Background(), newObj)
-	}); err != nil {
-		u.log.Error(err, "unable to update status", "name", update.NamespacedName.Name,
+	}); statusUpdateErr != nil {
+		u.log.Error(statusUpdateErr, "unable to update status", "name", update.NamespacedName.Name,
 			"namespace", update.NamespacedName.Namespace)
 	}
 }
@@ -233,7 +265,7 @@ func isStatusEqual(objA, objB interface{}) bool {
 				return true
 			}
 		}
-	case gwapiv1a3.BackendTLSPolicy:
+	case *gwapiv1a3.BackendTLSPolicy:
 		if b, ok := objB.(*gwapiv1a3.BackendTLSPolicy); ok {
 			if cmp.Equal(a.Status, b.Status, opts) {
 				return true