From 7bcb1a43265f90b400a909008184ec036061777c Mon Sep 17 00:00:00 2001
From: Niklas Walter <walter.niklas@gmail.com>
Date: Wed, 8 Apr 2026 14:10:18 +0200
Subject: [PATCH] Emit Warning events when scheduling is blocked by missing
 children

When the Wave reconciler detects missing or invalid ConfigMaps/Secrets,
it now emits a Kubernetes Warning event with reason 'MissingChildren'
and details of what's missing (e.g. 'missing required configmap default/foo').

Also change the webhook-path 'SchedulingDisabled' event from EventTypeNormal
to EventTypeWarning, since blocking scheduling is a warning condition.

Closes #186 (wave-k8s/wave)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 pkg/core/controller_suite.go | 38 ++++++++++++++++++++++++++++++++++++
 pkg/core/handler.go          |  3 ++-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/pkg/core/controller_suite.go b/pkg/core/controller_suite.go
index d3b0352..08b836a 100644
--- a/pkg/core/controller_suite.go
+++ b/pkg/core/controller_suite.go
@@ -458,6 +458,25 @@ func ControllerTestSuite[I InstanceType](
 			Expect(instance.GetAnnotations()[SchedulingDisabledAnnotation]).To(Equal("default-scheduler"))
 		})
 
+		It("Emits a MissingChildren warning event", func() {
+			eventReason := func(event *corev1.Event) string {
+				return event.Reason
+			}
+			eventType := func(event *corev1.Event) string {
+				return event.Type
+			}
+			Eventually(func() *corev1.EventList {
+				events := &corev1.EventList{}
+				Expect(m.Client.List(context.TODO(), events)).To(Succeed())
+				return events
+			}, timeout).Should(utils.WithItems(ContainElement(
+				SatisfyAll(
+					WithTransform(eventReason, Equal("MissingChildren")),
+					WithTransform(eventType, Equal(corev1.EventTypeWarning)),
+				),
+			)))
+		})
+
 		Context("And the missing child is created", func() {
 			JustBeforeEach(func() {
 				expectNoReconciles()
@@ -559,6 +578,25 @@ func ControllerTestSuite[I InstanceType](
 			Expect(instance.GetAnnotations()[SchedulingDisabledAnnotation]).To(Equal("default-scheduler"))
 		})
 
+		It("Emits a MissingChildren warning event", func() {
+			eventReason := func(event *corev1.Event) string {
+				return event.Reason
+			}
+			eventType := func(event *corev1.Event) string {
+				return event.Type
+			}
+			Eventually(func() *corev1.EventList {
+				events := &corev1.EventList{}
+				Expect(m.Client.List(context.TODO(), events)).To(Succeed())
+				return events
+			}, timeout).Should(utils.WithItems(ContainElement(
+				SatisfyAll(
+					WithTransform(eventReason, Equal("MissingChildren")),
+					WithTransform(eventType, Equal(corev1.EventTypeWarning)),
+				),
+			)))
+		})
+
 		Context("And the missing child is created with a missing field", func() {
 			BeforeEach(func() {
 				expectNoReconciles()
diff --git a/pkg/core/handler.go b/pkg/core/handler.go
index 02c6dd4..a847e29 100644
--- a/pkg/core/handler.go
+++ b/pkg/core/handler.go
@@ -112,6 +112,7 @@ func (h *Handler[I]) handlePodController(ctx context.Context, instance I) (recon
 	err = h.checkRequiredChildren(configMaps, secrets, configMapsConfig, secretsConfig)
 	if err != nil {
 		// We are missing children but we added watchers for all children so we are done
+		h.recorder.Eventf(instance, corev1.EventTypeWarning, "MissingChildren", "Scheduling blocked due to missing children: %s", err)
 		return reconcile.Result{}, nil
 	}
 
@@ -191,7 +192,7 @@ func (h *Handler[I]) updatePodController(instance I, dryRun bool, isCreate bool)
 		if isCreate {
 			if !dryRun {
 				log.V(0).Info("Not all required children found yet. Disabling scheduling!", "err", err)
-				h.recorder.Eventf(instance, corev1.EventTypeNormal, "SchedulingDisabled", "Disabled scheduling due to missing children: %s", err)
+				h.recorder.Eventf(instance, corev1.EventTypeWarning, "SchedulingDisabled", "Disabled scheduling due to missing children: %s", err)
 			}
 			disableScheduling(instance)
 		} else {