Added serialization from etcd error metric

staging/src/k8s.io/apiserver/pkg/storage/etcd3/metrics/metrics.go

@@ -113,6 +113,15 @@ var (
 		},
 		[]string{"resource"},
 	)
+	decodeErrorCounts = compbasemetrics.NewCounterVec(
+		&compbasemetrics.CounterOpts{
+			Namespace:      "apiserver",
+			Name:           "storage_decode_errors_total",
+			Help:           "Number of stored object decode errors split by object type",
+			StabilityLevel: compbasemetrics.ALPHA,
+		},
+		[]string{"resource"},
+	)
 )
 
 var registerMetrics sync.Once
@@ -130,6 +139,7 @@ func Register() {
 		legacyregistry.MustRegister(listStorageNumFetched)
 		legacyregistry.MustRegister(listStorageNumSelectorEvals)
 		legacyregistry.MustRegister(listStorageNumReturned)
+		legacyregistry.MustRegister(decodeErrorCounts)
 	})
 }
 
@@ -148,6 +158,11 @@ func RecordEtcdBookmark(resource string) {
 	etcdBookmarkCounts.WithLabelValues(resource).Inc()
 }
 
+// RecordDecodeError sets the storage_decode_errors metrics.
+func RecordDecodeError(resource string) {
+	decodeErrorCounts.WithLabelValues(resource).Inc()
+}
+
 // Reset resets the etcd_request_duration_seconds metric.
 func Reset() {
 	etcdRequestLatency.Reset()

staging/src/k8s.io/apiserver/pkg/storage/etcd3/metrics/metrics_test.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2023 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 (
+	"strings"
+	"testing"
+
+	"k8s.io/component-base/metrics"
+	"k8s.io/component-base/metrics/testutil"
+)
+
+func TestRecordDecodeError(t *testing.T) {
+	registry := metrics.NewKubeRegistry()
+	defer registry.Reset()
+	registry.Register(decodeErrorCounts)
+	resourceName := "pods"
+	testedMetrics := "apiserver_storage_decode_errors_total"
+	testCases := []struct {
+		desc     string
+		resource string
+		want     string
+	}{
+		{
+			desc:     "test success",
+			resource: resourceName,
+			want: `
+		# HELP apiserver_storage_decode_errors_total [ALPHA] Number of stored object decode errors split by object type
+		# TYPE apiserver_storage_decode_errors_total counter
+		apiserver_storage_decode_errors_total{resource="pods"} 1
+`,
+		},
+	}
+
+	for _, test := range testCases {
+		t.Run(test.desc, func(t *testing.T) {
+			RecordDecodeError(test.resource)
+			if err := testutil.GatherAndCompare(registry, strings.NewReader(test.want), testedMetrics); err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}

staging/src/k8s.io/apiserver/pkg/storage/etcd3/store.go

@@ -156,7 +156,12 @@ func (s *store) Get(ctx context.Context, key string, opts storage.GetOptions, ou
 		return storage.NewInternalError(err.Error())
 	}
 
-	return decode(s.codec, s.versioner, data, out, kv.ModRevision)
+	err = decode(s.codec, s.versioner, data, out, kv.ModRevision)
+	if err != nil {
+		recordDecodeError(s.groupResourceString, preparedKey)
+		return err
+	}
+	return nil
 }
 
 // Create implements storage.Interface.Create.
@@ -220,6 +225,7 @@ func (s *store) Create(ctx context.Context, key string, obj, out runtime.Object,
 		err = decode(s.codec, s.versioner, data, out, putResp.Header.Revision)
 		if err != nil {
 			span.AddEvent("decode failed", attribute.Int("len", len(data)), attribute.String("err", err.Error()))
+			recordDecodeError(s.groupResourceString, preparedKey)
 			return err
 		}
 		span.AddEvent("decode succeeded", attribute.Int("len", len(data)))
@@ -352,7 +358,12 @@ func (s *store) conditionalDelete(
 		if deleteResp.Header == nil {
 			return errors.New("invalid DeleteRange response - nil header")
 		}
-		return decode(s.codec, s.versioner, origState.data, out, deleteResp.Header.Revision)
+		err = decode(s.codec, s.versioner, origState.data, out, deleteResp.Header.Revision)
+		if err != nil {
+			recordDecodeError(s.groupResourceString, key)
+			return err
+		}
+		return nil
 	}
 }
 
@@ -470,7 +481,12 @@ func (s *store) GuaranteedUpdate(
 			}
 			// recheck that the data from etcd is not stale before short-circuiting a write
 			if !origState.stale {
-				return decode(s.codec, s.versioner, origState.data, destination, origState.rev)
+				err = decode(s.codec, s.versioner, origState.data, destination, origState.rev)
+				if err != nil {
+					recordDecodeError(s.groupResourceString, preparedKey)
+					return err
+				}
+				return nil
 			}
 		}
 
@@ -518,6 +534,7 @@ func (s *store) GuaranteedUpdate(
 		err = decode(s.codec, s.versioner, data, destination, putResp.Header.Revision)
 		if err != nil {
 			span.AddEvent("decode failed", attribute.Int("len", len(data)), attribute.String("err", err.Error()))
+			recordDecodeError(s.groupResourceString, preparedKey)
 			return err
 		}
 		span.AddEvent("decode succeeded", attribute.Int("len", len(data)))
@@ -745,6 +762,7 @@ func (s *store) GetList(ctx context.Context, key string, opts storage.ListOption
 			}
 
 			if err := appendListItem(v, data, uint64(kv.ModRevision), pred, s.codec, s.versioner, newItemFunc); err != nil {
+				recordDecodeError(s.groupResourceString, string(kv.Key))
 				return err
 			}
 			numEvald++
@@ -884,6 +902,7 @@ func (s *store) getState(ctx context.Context, getResp *clientv3.GetResponse, key
 		state.data = data
 		state.stale = stale
 		if err := decode(s.codec, s.versioner, state.data, state.obj, state.rev); err != nil {
+			recordDecodeError(s.groupResourceString, key)
 			return nil, err
 		}
 	}
@@ -1022,6 +1041,12 @@ func appendListItem(v reflect.Value, data []byte, rev uint64, pred storage.Selec
 	return nil
 }
 
+// recordDecodeError record decode error split by object type.
+func recordDecodeError(resource string, key string) {
+	metrics.RecordDecodeError(resource)
+	klog.V(4).Infof("Decoding %s \"%s\" failed", resource, key)
+}
+
 func notFound(key string) clientv3.Cmp {
 	return clientv3.Compare(clientv3.ModRevision(key), "=", 0)
 }