Allow setting sizeLimit when persistence disabled

api/v1beta1/rabbitmqcluster_types.go

@@ -412,6 +412,24 @@ type RabbitmqClusterPersistenceSpec struct {
 	// See https://pkg.go.dev/k8s.io/apimachinery/pkg/api/resource#Quantity for more info on the format of this field.
 	// +kubebuilder:default:="10Gi"
 	Storage *k8sresource.Quantity `json:"storage,omitempty"`
+	// EmptyDir configuration to be used when Storage is set to 0Gi.
+	// +optional
+	EmptyDir *RabbitmqClusterEmptyDirSpec `json:"emptyDir,omitempty"`
+}
+
+// RabbitmqClusterEmptyDirSpec contains configuration for EmptyDir volumes.
+type RabbitmqClusterEmptyDirSpec struct {
+	// Medium represents the storage medium for the EmptyDir volume.
+	// The default is "" which means to use the node's default medium.
+	// Must be an empty string (default) or Memory.
+	// More info: https://kubernetes.io/docs/concepts/storage/volumes#emptydir
+	// +optional
+	Medium corev1.StorageMedium `json:"medium,omitempty"`
+	// SizeLimit sets the size limit for EmptyDir volumes.
+	// The format of this field matches that defined by kubernetes/apimachinery.
+	// See https://pkg.go.dev/k8s.io/apimachinery/pkg/api/resource#Quantity for more info on the format of this field.
+	// +optional
+	SizeLimit *k8sresource.Quantity `json:"sizeLimit,omitempty"`
 }
 
 // Settable attributes for the Service resource.

config/crd/bases/rabbitmq.com_rabbitmqclusters.yaml

@@ -5069,6 +5069,27 @@ spec:
                     storage: 10Gi
                   description: The desired persistent storage configuration for each Pod in the cluster.
                   properties:
+                    emptyDir:
+                      description: EmptyDir configuration to be used when Storage is set to 0Gi.
+                      properties:
+                        medium:
+                          description: |-
+                            Medium represents the storage medium for the EmptyDir volume.
+                            The default is "" which means to use the node's default medium.
+                            Must be an empty string (default) or Memory.
+                            More info: https://kubernetes.io/docs/concepts/storage/volumes#emptydir
+                          type: string
+                        sizeLimit:
+                          anyOf:
+                            - type: integer
+                            - type: string
+                          description: |-
+                            SizeLimit sets the size limit for EmptyDir volumes.
+                            The format of this field matches that defined by kubernetes/apimachinery.
+                            See https://pkg.go.dev/k8s.io/apimachinery/pkg/api/resource#Quantity for more info on the format of this field.
+                          pattern: ^(\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))(([KMGTPE]i)|[numkMGTPE]|([eE](\+|-)?(([0-9]+(\.[0-9]*)?)|(\.[0-9]+))))?$
+                          x-kubernetes-int-or-string: true
+                      type: object
                     storage:
                       anyOf:
                         - type: integer

docs/api/rabbitmq.com.ref.asciidoc

@@ -227,6 +227,29 @@ user.
 |===
 
 
+[id="{anchor_prefix}-github-com-rabbitmq-cluster-operator-v2-api-v1beta1-rabbitmqclusteremptydirspec"]
+==== RabbitmqClusterEmptyDirSpec 
+
+RabbitmqClusterEmptyDirSpec contains configuration for EmptyDir volumes.
+
+.Appears In:
+****
+- xref:{anchor_prefix}-github-com-rabbitmq-cluster-operator-v2-api-v1beta1-rabbitmqclusterpersistencespec[$$RabbitmqClusterPersistenceSpec$$]
+****
+
+[cols="25a,75a", options="header"]
+|===
+| Field | Description
+| *`medium`* __link:https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.23/#storagemedium-v1-core[$$StorageMedium$$]__ | Medium represents the storage medium for the EmptyDir volume.
+The default is "" which means to use the node's default medium.
+Must be an empty string (default) or Memory.
+More info: https://kubernetes.io/docs/concepts/storage/volumes#emptydir
+| *`sizeLimit`* __link:https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.23/#quantity-resource-api[$$Quantity$$]__ | SizeLimit sets the size limit for EmptyDir volumes.
+The format of this field matches that defined by kubernetes/apimachinery.
+See https://pkg.go.dev/k8s.io/apimachinery/pkg/api/resource#Quantity for more info on the format of this field.
+|===
+
+
 [id="{anchor_prefix}-github-com-rabbitmq-cluster-operator-v2-api-v1beta1-rabbitmqclusterlist"]
 ==== RabbitmqClusterList 
 
@@ -289,6 +312,7 @@ The settings for the persistent storage desired for each Pod in the RabbitmqClus
 | *`storage`* __link:https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.23/#quantity-resource-api[$$Quantity$$]__ | The requested size of the persistent volume attached to each Pod in the RabbitmqCluster.
 The format of this field matches that defined by kubernetes/apimachinery.
 See https://pkg.go.dev/k8s.io/apimachinery/pkg/api/resource#Quantity for more info on the format of this field.
+| *`emptyDir`* __xref:{anchor_prefix}-github-com-rabbitmq-cluster-operator-v2-api-v1beta1-rabbitmqclusteremptydirspec[$$RabbitmqClusterEmptyDirSpec$$]__ | EmptyDir configuration to be used when Storage is set to 0Gi.
 |===
 
 

internal/resource/statefulset.go

@@ -20,6 +20,8 @@ import (
 
 	"k8s.io/apimachinery/pkg/util/intstr"
 
+	"maps"
+
 	rabbitmqv1beta1 "github.com/rabbitmq/cluster-operator/v2/api/v1beta1"
 	"github.com/rabbitmq/cluster-operator/v2/internal/metadata"
 	appsv1 "k8s.io/api/apps/v1"
@@ -29,7 +31,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/strategicpatch"
 	"k8s.io/utils/ptr"
-	"maps"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
 )
@@ -456,12 +457,17 @@ func (builder *StatefulSetBuilder) podTemplateSpec(previousPodAnnotations map[st
 
 	zero := k8sresource.MustParse("0Gi")
 	if builder.Instance.Spec.Persistence.Storage.Cmp(zero) == 0 {
-		volumes = append(volumes, corev1.Volume{
+		volume := corev1.Volume{
 			Name: "persistence",
 			VolumeSource: corev1.VolumeSource{
 				EmptyDir: &corev1.EmptyDirVolumeSource{},
 			},
-		})
+		}
+		if builder.Instance.Spec.Persistence.EmptyDir != nil {
+			volume.VolumeSource.EmptyDir.SizeLimit = builder.Instance.Spec.Persistence.EmptyDir.SizeLimit
+			volume.VolumeSource.EmptyDir.Medium = builder.Instance.Spec.Persistence.EmptyDir.Medium
+		}
+		volumes = append(volumes, volume)
 	}
 
 	rabbitmqContainerVolumeMounts := []corev1.VolumeMount{

internal/resource/statefulset_test.go

@@ -1334,6 +1334,30 @@ default_pass = {{ .Data.data.password }}
 
 				Expect(statefulSet.Spec.Template.Spec.Volumes).To(ContainElement(expectedVolume))
 			})
+
+			It("defines an emptyDir volume with sizeLimit and medium when storage == 0 and emptyDir config received", func() {
+				zero, _ := k8sresource.ParseQuantity("0")
+
+				stsBuilder := builder.StatefulSet()
+				stsBuilder.Instance.Spec.Persistence.Storage = &zero
+				stsBuilder.Instance.Spec.Persistence.EmptyDir = &rabbitmqv1beta1.RabbitmqClusterEmptyDirSpec{
+					SizeLimit: ptr.To(k8sresource.MustParse("500Mi")),
+					Medium:    corev1.StorageMediumMemory,
+				}
+				Expect(stsBuilder.Update(statefulSet)).To(Succeed())
+
+				expectedVolume := corev1.Volume{
+					Name: "persistence",
+					VolumeSource: corev1.VolumeSource{
+						EmptyDir: &corev1.EmptyDirVolumeSource{
+							SizeLimit: ptr.To(k8sresource.MustParse("500Mi")),
+							Medium:    corev1.StorageMediumMemory,
+						},
+					},
+				}
+
+				Expect(statefulSet.Spec.Template.Spec.Volumes).To(ContainElement(expectedVolume))
+			})
 		})
 
 		It("uses the correct service account", func() {