COO-1384: fix(monitoringstack): correctly configure OTLP receiver

pkg/controllers/monitoring/monitoring-stack/components.go

@@ -202,12 +202,7 @@ func newPrometheus(
 				RemoteWrite:               config.RemoteWrite,
 				ExternalLabels:            config.ExternalLabels,
 				EnableRemoteWriteReceiver: config.EnableRemoteWriteReceiver,
-				EnableFeatures: func() []monv1.EnableFeature {
-					if config.EnableOtlpHttpReceiver != nil && *config.EnableOtlpHttpReceiver {
-						return []monv1.EnableFeature{"otlp-write-receiver"}
-					}
-					return []monv1.EnableFeature{}
-				}(),
+				EnableOTLPReceiver:        config.EnableOtlpHttpReceiver,
 			},
 			Retention:             ms.Spec.Retention,
 			RuleSelector:          prometheusSelector,

test/e2e/framework/assertions.go

@@ -159,6 +159,55 @@ func (f *Framework) AssertStatefulsetReady(name, namespace string, fns ...Option
 	}
 }
 
+// AssertStatefulSetContainerHasArg asserts that a specific container in a StatefulSet's
+// Pod template contains the expected command-line argument.
+func (f *Framework) AssertStatefulSetContainerHasArg(t *testing.T, name, namespace, containerName, expectedArg string, fns ...OptionFn) func(t *testing.T) {
+	option := AssertOption{
+		PollInterval: 5 * time.Second,
+		WaitTimeout:  DefaultTestTimeout,
+	}
+	for _, fn := range fns {
+		fn(&option)
+	}
+
+	return func(t *testing.T) {
+		t.Helper()
+		statefulSet := &appsv1.StatefulSet{}
+		key := types.NamespacedName{Name: name, Namespace: namespace}
+
+		if err := wait.PollUntilContextTimeout(context.Background(), option.PollInterval, option.WaitTimeout, true, func(ctx context.Context) (bool, error) {
+
+			if err := f.K8sClient.Get(ctx, key, statefulSet); apierrors.IsNotFound(err) {
+				return false, nil
+			}
+
+			var container *v1.Container
+			for i, c := range statefulSet.Spec.Template.Spec.Containers {
+				if c.Name == containerName {
+					container = &statefulSet.Spec.Template.Spec.Containers[i]
+					break
+				}
+			}
+
+			if container == nil {
+				return false, fmt.Errorf("container %q not found in StatefulSet template", containerName)
+			}
+
+			for _, arg := range container.Args {
+				if arg == expectedArg {
+					return true, nil
+				}
+			}
+
+			t.Logf("StatefulSet %s container %q args are missing %q. Retrying...", name, containerName, expectedArg)
+			return false, nil
+		}); wait.Interrupted(err) {
+			t.Fatalf("StatefulSet %s failed to contain argument %q in container %q within timeout. Final args: %v",
+				name, expectedArg, containerName, statefulSet.Spec.Template.Spec.Containers[0].Args)
+		}
+	}
+}
+
 // AssertDeploymentReady asserts that a deployment has the desired number of pods running
 func (f *Framework) AssertDeploymentReady(name, namespace string, fns ...OptionFn) func(t *testing.T) {
 	option := AssertOption{

test/e2e/monitoring_stack_controller_test.go

@@ -130,6 +130,9 @@ func TestMonitoringStackController(t *testing.T) {
 	}, {
 		name:     "Prometheus stacks can scrape themselves behind TLS",
 		scenario: assertPrometheusScrapesItselfTLS,
+	}, {
+		name:     "Assert OTLP receiver flag is set when enabled in CR",
+		scenario: assertDefaultOTLPFlagIsSet,
 	}}
 	for _, tc := range ts {
 		t.Run(tc.name, tc.scenario)
@@ -969,6 +972,18 @@ func assertPrometheusScrapesItselfTLS(t *testing.T) {
 	}
 }
 
+func assertDefaultOTLPFlagIsSet(t *testing.T) {
+	ms := newMonitoringStack(t, "otlp-flag-test")
+	ms.Spec.PrometheusConfig = &stack.PrometheusConfig{
+		EnableOtlpHttpReceiver: ptr.To(true),
+	}
+
+	err := f.K8sClient.Create(context.Background(), ms)
+	assert.NilError(t, err, "failed to create a monitoring stack")
+
+	f.AssertStatefulSetContainerHasArg(t, "prometheus-"+ms.Name, e2eTestNamespace, "prometheus", "--web.enable-otlp-receiver")(t)
+}
+
 // Update this json when a new Prometheus field is set by MonitoringStack
 const oboManagedFieldsJson = `
 {
@@ -998,9 +1013,7 @@ const oboManagedFieldsJson = `
   "f:probeNamespaceSelector": {},
   "f:probeSelector": {},
   "f:remoteWrite": {},
-  "f:enableFeatures": {
-    "v:\"otlp-write-receiver\"": {}
-  },
+  "f:enableOTLPReceiver": {},
   "f:replicas": {},
   "f:resources": {},
   "f:retention": {},