[receiver/k8s_cluster] Do not store unused service data in k8s API ca…

…che (open-telemetry#23434)

To reduce RAM utilization.

Resolves
open-telemetry#23433

This is the last PR to reduce the memory footprint of k8s API informers.
Other objects are more static and usually don't have a lot of instances
in user clusters, so there is no need to reduce their size.

receiver/k8sclusterreceiver/informer_transform.go

@@ -14,6 +14,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/node"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/pod"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/replicaset"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/service"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/statefulset"
 )
 
@@ -35,6 +36,8 @@ func transformObject(object interface{}) (interface{}, error) {
 		return demonset.Transform(o), nil
 	case *appsv1.StatefulSet:
 		return statefulset.Transform(o), nil
+	case *corev1.Service:
+		return service.Transform(o), nil
 	}
 	return object, nil
 }

receiver/k8sclusterreceiver/informer_transform_test.go

@@ -93,6 +93,25 @@ func TestTransformObject(t *testing.T) {
 			},
 			same: false,
 		},
+		{
+			name: "service",
+			object: &corev1.Service{
+				Spec: corev1.ServiceSpec{
+					Selector: map[string]string{
+						"app": "my-app",
+					},
+					Type: corev1.ServiceTypeClusterIP,
+				},
+			},
+			want: &corev1.Service{
+				Spec: corev1.ServiceSpec{
+					Selector: map[string]string{
+						"app": "my-app",
+					},
+				},
+			},
+			same: false,
+		},
 		{
 			// This is a case where we don't transform the object.
 			name:   "hpa",

receiver/k8sclusterreceiver/internal/pod/pods.go

@@ -4,7 +4,6 @@
 package pod // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/pod"
 
 import (
-	"fmt"
 	"strings"
 	"time"
 
@@ -17,7 +16,6 @@ import (
 	batchv1 "k8s.io/api/batch/v1"
 	corev1 "k8s.io/api/core/v1"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/tools/cache"
 
@@ -26,6 +24,7 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/constants"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/container"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/metadata"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/service"
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/utils"
 )
 
@@ -184,7 +183,7 @@ func GetMetadata(pod *corev1.Pod, mc *metadata.Store, logger *zap.Logger) map[ex
 	}
 
 	if mc.Services != nil {
-		meta = maps.MergeStringMaps(meta, getPodServiceTags(pod, mc.Services))
+		meta = maps.MergeStringMaps(meta, service.GetPodServiceTags(pod, mc.Services))
 	}
 
 	if mc.Jobs != nil {
@@ -268,21 +267,6 @@ func logError(err error, ref *v1.OwnerReference, podUID types.UID, logger *zap.L
 	)
 }
 
-// getPodServiceTags returns a set of services associated with the pod.
-func getPodServiceTags(pod *corev1.Pod, services cache.Store) map[string]string {
-	properties := map[string]string{}
-
-	for _, ser := range services.List() {
-		serObj := ser.(*corev1.Service)
-		if serObj.Namespace == pod.Namespace &&
-			labels.Set(serObj.Spec.Selector).AsSelectorPreValidated().Matches(labels.Set(pod.Labels)) {
-			properties[fmt.Sprintf("%s%s", constants.K8sServicePrefix, serObj.Name)] = ""
-		}
-	}
-
-	return properties
-}
-
 // getWorkloadProperties returns workload metadata for provided owner reference.
 func getWorkloadProperties(ref *v1.OwnerReference, labelKey string) map[string]string {
 	uidKey := metadata.GetOTelUIDFromKind(strings.ToLower(ref.Kind))

receiver/k8sclusterreceiver/internal/service/service.go

@@ -0,0 +1,40 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package service // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/service"
+import (
+	"fmt"
+
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	"k8s.io/client-go/tools/cache"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/constants"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/k8sclusterreceiver/internal/metadata"
+)
+
+// Transform transforms the pod to remove the fields that we don't use to reduce RAM utilization.
+// IMPORTANT: Make sure to update this function before using new service fields.
+func Transform(service *corev1.Service) *corev1.Service {
+	return &corev1.Service{
+		ObjectMeta: metadata.TransformObjectMeta(service.ObjectMeta),
+		Spec: corev1.ServiceSpec{
+			Selector: service.Spec.Selector,
+		},
+	}
+}
+
+// GetPodServiceTags returns a set of services associated with the pod.
+func GetPodServiceTags(pod *corev1.Pod, services cache.Store) map[string]string {
+	properties := map[string]string{}
+
+	for _, ser := range services.List() {
+		serObj := ser.(*corev1.Service)
+		if serObj.Namespace == pod.Namespace &&
+			labels.Set(serObj.Spec.Selector).AsSelectorPreValidated().Matches(labels.Set(pod.Labels)) {
+			properties[fmt.Sprintf("%s%s", constants.K8sServicePrefix, serObj.Name)] = ""
+		}
+	}
+
+	return properties
+}

receiver/k8sclusterreceiver/internal/service/service_test.go

@@ -0,0 +1,55 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestTransform(t *testing.T) {
+	originalService := &corev1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "my-service",
+			Namespace: "default",
+			Labels: map[string]string{
+				"app": "my-app",
+			},
+			Annotations: map[string]string{
+				"annotation1": "value1",
+			},
+		},
+		Spec: corev1.ServiceSpec{
+			Selector: map[string]string{
+				"app": "my-app",
+			},
+			Ports: []corev1.ServicePort{
+				{
+					Name:     "http",
+					Port:     80,
+					Protocol: corev1.ProtocolTCP,
+				},
+			},
+			Type: corev1.ServiceTypeClusterIP,
+		},
+	}
+	wantService := &corev1.Service{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "my-service",
+			Namespace: "default",
+			Labels: map[string]string{
+				"app": "my-app",
+			},
+		},
+		Spec: corev1.ServiceSpec{
+			Selector: map[string]string{
+				"app": "my-app",
+			},
+		},
+	}
+	assert.EqualValues(t, wantService, Transform(originalService))
+}