Set watch option

.chloggen/set-cache-watch-option.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. collector, target allocator, auto-instrumentation, opamp, github action)
+component: collector
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Adds a label selector to the operator's informer cache to only select resources with the label selector
+
+# One or more tracking issues related to the change
+issues: [2822]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

main.go

@@ -28,7 +28,10 @@ import (
 	monitoringv1 "github.com/prometheus-operator/prometheus-operator/pkg/apis/monitoring/v1"
 	"github.com/spf13/pflag"
 	colfeaturegate "go.opentelemetry.io/collector/featuregate"
+	appsv1 "k8s.io/api/apps/v1"
+	v1 "k8s.io/api/batch/v1"
 	networkingv1 "k8s.io/api/networking/v1"
+	"k8s.io/apimachinery/pkg/labels"
 	k8sruntime "k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/client-go/kubernetes"
@@ -38,6 +41,7 @@ import (
 	k8sapiflag "k8s.io/component-base/cli/flag"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
@@ -273,9 +277,24 @@ func main() {
 			Port:    webhookPort,
 			TLSOpts: optionsTlSOptsFuncs,
 		}),
-		Cache: cache.Options{
+	}
+
+	if featuregate.EnableCacheOptions.IsEnabled() {
+		mgrOptions.Cache = cache.Options{
 			DefaultNamespaces: namespaces,
-		},
+			DefaultLabelSelector: labels.SelectorFromSet(map[string]string{
+				"app.kubernetes.io/managed-by": "opentelemetry-operator",
+			}),
+			ByObject: map[client.Object]cache.ByObject{
+				&otelv1alpha1.OpenTelemetryCollector{}: {},
+				&otelv1alpha1.OpAMPBridge{}:            {},
+				&otelv1alpha1.Instrumentation{}:        {},
+				&v1.Job{}:                              {},
+				&appsv1.Deployment{}:                   {},
+				&appsv1.DaemonSet{}:                    {},
+				&appsv1.StatefulSet{}:                  {},
+			},
+		}
 	}
 
 	mgr, err := ctrl.NewManager(restConfig, mgrOptions)

pkg/featuregate/featuregate.go

@@ -60,6 +60,14 @@ var (
 		featuregate.WithRegisterDescription("enables features associated to the Prometheus Operator"),
 		featuregate.WithRegisterFromVersion("v0.82.0"),
 	)
+
+	// EnableCacheOptions is the feature gate that sets a cache label selector to improve operator performance.
+	EnableCacheOptions = featuregate.GlobalRegistry().MustRegister(
+		"operator.cache.selector",
+		featuregate.StageBeta, // TODO: this is temporary and will be reverted prior to an e2e run
+		featuregate.WithRegisterDescription("enables the operator's cache to only select a subset of objects"),
+		featuregate.WithRegisterFromVersion("v0.98.0"),
+	)
 )
 
 // Flags creates a new FlagSet that represents the available featuregate flags using the supplied featuregate registry.