Add rabbitmq.com/disable-default-topology-spread-constraints annotation

When the annotation rabbitmq.com/disable-default-topology-spread-constraints is set to "true" the default
topologySpreadConstraints based on label topology.kubernetes.io/zone is ommited.

Author: DanielDorado

api/v1beta1/rabbitmqcluster_types.go

@@ -21,6 +21,8 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
+const DisableDefaultTopologySpreadAnnotation = "rabbitmq.com/disable-default-topology-spread-constraints"
+
 // +kubebuilder:object:root=true
 // +kubebuilder:subresource:status
 // +kubebuilder:printcolumn:name="AllReplicasReady",type="string",JSONPath=".status.conditions[?(@.type == 'AllReplicasReady')].status"
@@ -506,6 +508,14 @@ func (cluster RabbitmqCluster) PVCName(i int) string {
 	return strings.Join([]string{"persistence", cluster.Name, "server", strconv.Itoa(i)}, "-")
 }
 
+func (cluster RabbitmqCluster) DisableDefaultTopologySpreadConstraints() bool {
+	value, ok := cluster.Annotations[DisableDefaultTopologySpreadAnnotation]
+	if ok && strings.TrimSpace(value) == "true" {
+		return true
+	}
+	return false
+}
+
 func init() {
 	SchemeBuilder.Register(&RabbitmqCluster{}, &RabbitmqClusterList{})
 }

internal/resource/statefulset.go

@@ -551,19 +551,7 @@ func (builder *StatefulSetBuilder) podTemplateSpec(previousPodAnnotations map[st
 			Labels:      metadata.Label(builder.Instance.Name),
 		},
 		Spec: corev1.PodSpec{
-			TopologySpreadConstraints: []corev1.TopologySpreadConstraint{
-				{
-					MaxSkew: 1,
-					// "topology.kubernetes.io/zone" is a well-known label.
-					// It is automatically set by kubelet if the cloud provider provides the zone information.
-					// See: https://kubernetes.io/docs/reference/kubernetes-api/labels-annotations-taints/#topologykubernetesiozone
-					TopologyKey:       "topology.kubernetes.io/zone",
-					WhenUnsatisfiable: corev1.ScheduleAnyway,
-					LabelSelector: &metav1.LabelSelector{
-						MatchLabels: metadata.LabelSelector(builder.Instance.Name),
-					},
-				},
-			},
+			TopologySpreadConstraints: builder.defaultTopologySpreadConstraints(),
 			SecurityContext: &corev1.PodSecurityContext{
 				FSGroup:   ptr.To(int64(0)),
 				RunAsUser: &rabbitmqUID,
@@ -1088,6 +1076,27 @@ func (builder *StatefulSetBuilder) updateContainerPortsOnlyTLSListeners() []core
 	return ports
 }
 
+func (builder *StatefulSetBuilder) defaultTopologySpreadConstraints() []corev1.TopologySpreadConstraint {
+
+	if builder.Instance.DisableDefaultTopologySpreadConstraints() {
+		return []corev1.TopologySpreadConstraint{}
+	}
+
+	return []corev1.TopologySpreadConstraint{
+		{
+			MaxSkew: 1,
+			// "topology.kubernetes.io/zone" is a well-known label.
+			// It is automatically set by kubelet if the cloud provider provides the zone information.
+			// See: https://kubernetes.io/docs/reference/kubernetes-api/labels-annotations-taints/#topologykubernetesiozone
+			TopologyKey:       "topology.kubernetes.io/zone",
+			WhenUnsatisfiable: corev1.ScheduleAnyway,
+			LabelSelector: &metav1.LabelSelector{
+				MatchLabels: metadata.LabelSelector(builder.Instance.Name),
+			},
+		},
+	}
+}
+
 func copyLabelsAnnotations(base *metav1.ObjectMeta, override rabbitmqv1beta1.EmbeddedLabelsAnnotations) {
 	if override.Labels != nil {
 		base.Labels = mergeMap(base.Labels, override.Labels)

internal/resource/statefulset_test.go

@@ -2138,6 +2138,87 @@ default_pass = {{ .Data.data.password }}
 
 				})
 
+				Context("TopologySpreadConstraints composition", func() {
+					BeforeEach(func() {
+						instance.Spec.Override.StatefulSet = &rabbitmqv1beta1.StatefulSet{
+							Spec: &rabbitmqv1beta1.StatefulSetSpec{
+								Template: &rabbitmqv1beta1.PodTemplateSpec{
+									Spec: &corev1.PodSpec{},
+								},
+							},
+						}
+						builder = &resource.RabbitmqResourceBuilder{
+							Instance: &instance,
+							Scheme:   scheme,
+						}
+					})
+					When("Default TopologySpreadConstraints", func() {
+						It("uses the default", func() {
+							stsBuilder := builder.StatefulSet()
+							Expect(stsBuilder.Update(statefulSet)).To(Succeed())
+							Expect(statefulSet.Spec.Template.Spec.TopologySpreadConstraints).To(ConsistOf(
+								corev1.TopologySpreadConstraint{
+									MaxSkew:           1,
+									TopologyKey:       "topology.kubernetes.io/zone",
+									WhenUnsatisfiable: corev1.ScheduleAnyway,
+									LabelSelector: &metav1.LabelSelector{
+										MatchLabels: map[string]string{
+											"app.kubernetes.io/name": instance.Name,
+										},
+									},
+								},
+							))
+						})
+					})
+					When("Disable Default TopologySpreadConstraints", func() {
+						It("does not have any constraint", func() {
+							instance.Annotations = map[string]string{rabbitmqv1beta1.DisableDefaultTopologySpreadAnnotation: "true"}
+							stsBuilder := builder.StatefulSet()
+							Expect(stsBuilder.Update(statefulSet)).To(Succeed())
+							Expect(statefulSet.Spec.Template.Spec.TopologySpreadConstraints).To(BeEmpty())
+						})
+					})
+					When("Disable Default TopologySpreadConstraints and override has a value", func() {
+						It("overrides the default", func() {
+							instance.Annotations = map[string]string{rabbitmqv1beta1.DisableDefaultTopologySpreadAnnotation: "true"}
+							instance.Spec.Override.StatefulSet = &rabbitmqv1beta1.StatefulSet{
+								Spec: &rabbitmqv1beta1.StatefulSetSpec{
+									Template: &rabbitmqv1beta1.PodTemplateSpec{
+										Spec: &corev1.PodSpec{
+											TopologySpreadConstraints: []corev1.TopologySpreadConstraint{
+												{
+													MaxSkew:           1,
+													TopologyKey:       "my-topology",
+													WhenUnsatisfiable: corev1.DoNotSchedule,
+													LabelSelector: &metav1.LabelSelector{
+														MatchLabels: map[string]string{
+															"key": "value",
+														},
+													},
+												},
+											},
+										},
+									},
+								},
+							}
+							stsBuilder := builder.StatefulSet()
+							Expect(stsBuilder.Update(statefulSet)).To(Succeed())
+							Expect(statefulSet.Spec.Template.Spec.TopologySpreadConstraints).To(ConsistOf(
+								corev1.TopologySpreadConstraint{
+									MaxSkew:           1,
+									TopologyKey:       "my-topology",
+									WhenUnsatisfiable: corev1.DoNotSchedule,
+									LabelSelector: &metav1.LabelSelector{
+										MatchLabels: map[string]string{
+											"key": "value",
+										},
+									},
+								},
+							))
+						})
+					})
+				})
+
 				Context("Rabbitmq Container volume mounts", func() {
 					It("Overrides the volume mounts list while making sure that '/var/lib/rabbitmq/' mounts before '/var/lib/rabbitmq/mnesia/' ", func() {
 						instance.Spec.Override.StatefulSet = &rabbitmqv1beta1.StatefulSet{