chore: review, adds unit tests

Signed-off-by: Armando Ruocco <armando.ruocco@enterprisedb.com>

api/v1/cluster_webhook.go

@@ -1479,10 +1479,10 @@ func (r *Cluster) validateWalStorageSize() field.ErrorList {
 func (r *Cluster) validateEphemeralVolumeSource() field.ErrorList {
 	var result field.ErrorList
 
-	if r.Spec.EphemeralVolumeSource != nil && (r.Spec.EphemeralVolumesSizeLimit != nil && r.Spec.EphemeralVolumesSizeLimit.TemporaryData != nil) {
+	if r.Spec.EphemeralVolumeSource != nil && r.Spec.EphemeralVolumesSizeLimit != nil {
 		result = append(result, field.Duplicate(
 			field.NewPath("spec", "ephemeralVolumeSource"),
-			"ephemeralVolumeSource and ephemeralVolumesSizeLimit.temporaryData are in conflict, set one only",
+			"Conflicting settings: provide either ephemeralVolumeSource or ephemeralVolumesSizeLimit, not both.",
 		))
 	}
 

docs/src/cluster_conf.md

@@ -47,13 +47,12 @@ CloudNativePG relies on [ephemeral volumes](https://kubernetes.io/docs/concepts/
 for part of the internal activities. Ephemeral volumes exist for the sole
 duration of a pod's life, without persisting across pod restarts.
 
-### Volume for temporary storage
+# Volume Claim Template for Temporary Storage
 
-An ephemeral volume used for temporary storage. By default an `emptyDir` volume is used. To configure
-the volume use the `.spec.ephemeralVolumeSource` field in the cluster spec.
+The operator uses  by default an `emptyDir` volume, which can be customized by using the `.spec.ephemeralVolumesSizeLimit field`.
+This can be overridden by specifying a volume claim template in the `.spec.ephemeralVolumeSource` field.
 
-This simple example shows how to set a `1Gi` ephemeral volume. Set the `storageClassName` to something
-available on your Kubernetes cluster.
+In the following example, a `1Gi` ephemeral volume is set.
 
 ```yaml
 apiVersion: postgresql.cnpg.io/v1
@@ -66,16 +65,14 @@ spec:
     volumeClaimTemplate:
       spec:
         accessModes: ["ReadWriteOnce"]
+        # example storageClassName, replace with one existing in your Kubernetes cluster
         storageClassName: "scratch-storage-class"
         resources:
           requests:
             storage: 1Gi
 ```
 
-Alternatively you can configure an upper bound on the default volume size using the `.spec.ephemeralVolumesSizeLimit.temporaryData`
-field in the cluster spec.
-
-Both `.spec.emphemeralVolumeSource` and `.spec.ephemeralVolumesSizeLimit.temporaryData` cannot be set.
+Both `.spec.emphemeralVolumeSource` and `.spec.ephemeralVolumesSizeLimit.temporaryData` cannot be specified simultaneously.
 
 ### Volume for shared memory
 

pkg/specs/volumes_test.go

@@ -18,6 +18,8 @@ package specs
 
 import (
 	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/utils/ptr"
 
 	apiv1 "github.com/cloudnative-pg/cloudnative-pg/api/v1"
 
@@ -472,3 +474,47 @@ var _ = DescribeTable("test creation of volumes",
 			},
 		}),
 )
+
+var _ = Describe("createEphemeralVolume", func() {
+	var cluster apiv1.Cluster
+
+	BeforeEach(func() {
+		cluster = apiv1.Cluster{}
+	})
+
+	It("should create an emptyDir volume by default", func() {
+		ephemeralVolume := createEphemeralVolume(cluster)
+		Expect(ephemeralVolume.Name).To(Equal("scratch-data"))
+		Expect(ephemeralVolume.VolumeSource.EmptyDir).NotTo(BeNil())
+	})
+
+	It("should create an ephemeral volume when specified in the cluster", func() {
+		const storageClass = "test-storageclass"
+		cluster.Spec.EphemeralVolumeSource = &corev1.EphemeralVolumeSource{
+			VolumeClaimTemplate: &corev1.PersistentVolumeClaimTemplate{
+				Spec: corev1.PersistentVolumeClaimSpec{
+					StorageClassName: ptr.To(storageClass),
+				},
+			},
+		}
+
+		ephemeralVolume := createEphemeralVolume(cluster)
+
+		Expect(ephemeralVolume.Name).To(Equal("scratch-data"))
+		Expect(ephemeralVolume.EmptyDir).To(BeNil())
+		Expect(ephemeralVolume.VolumeSource.Ephemeral).NotTo(BeNil())
+		Expect(*ephemeralVolume.VolumeSource.Ephemeral.VolumeClaimTemplate.Spec.StorageClassName).To(Equal(storageClass))
+	})
+
+	It("should set size limit when specified in the cluster", func() {
+		quantity := resource.MustParse("1Gi")
+		cluster.Spec.EphemeralVolumesSizeLimit = &apiv1.EphemeralVolumesSizeLimitConfiguration{
+			TemporaryData: &quantity,
+		}
+
+		ephemeralVolume := createEphemeralVolume(cluster)
+
+		Expect(ephemeralVolume.Name).To(Equal("scratch-data"))
+		Expect(*ephemeralVolume.VolumeSource.EmptyDir.SizeLimit).To(Equal(quantity))
+	})
+})