feat: add ephemeralVolumeSource option to cluster spec. (#3678)

Allow the user to optionally set the `ephemeralStorage` option in the cluster spec. Closes #3677 Refs: - #3677 - #317 Signed-off-by: Josh Fyne <josh.fyne@gmail.com> Signed-off-by: Armando Ruocco <armando.ruocco@enterprisedb.com> Co-authored-by: Armando Ruocco <armando.ruocco@enterprisedb.com>
cloudnative-pg · Jan 23, 2024 · 0e7ac95 · 0e7ac95
1 parent ca6be9d
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Showing 10 changed files with 425 additions and 12 deletions.
diff --git a/.wordlist-en-custom.txt b/.wordlist-en-custom.txt
@@ -126,6 +126,7 @@ EnterpriseDB's
 EnvFrom
 EnvFromSource
 EnvVar
+EphemeralVolumeSource
 EphemeralVolumesSizeLimit
 EphemeralVolumesSizeLimitConfiguration
 ExternalCluster
@@ -649,6 +650,7 @@ endpointURL
 enterprisedb
 env
 envFrom
+ephemeralVolumeSource
 ephemeralVolumesSizeLimit
 executables
 expirations

diff --git a/api/v1/cluster_types.go b/api/v1/cluster_types.go
@@ -338,6 +338,10 @@ type ClusterSpec struct {
 	// +optional
 	WalStorage *StorageConfiguration `json:"walStorage,omitempty"`
 
+	// EphemeralVolumeSource allows the user to configure the source of ephemeral volumes.
+	// +optional
+	EphemeralVolumeSource *corev1.EphemeralVolumeSource `json:"ephemeralVolumeSource,omitempty"`
+
 	// The time in seconds that is allowed for a PostgreSQL instance to
 	// successfully start up (default 3600).
 	// The startup probe failure threshold is derived from this value using the formula:

diff --git a/api/v1/cluster_webhook.go b/api/v1/cluster_webhook.go
@@ -309,6 +309,7 @@ func (r *Cluster) Validate() (allErrs field.ErrorList) {
 		r.validateMaxSyncReplicas,
 		r.validateStorageSize,
 		r.validateWalStorageSize,
+		r.validateEphemeralVolumeSource,
 		r.validateTablespaceStorageSize,
 		r.validateName,
 		r.validateTablespaceNames,
@@ -1475,6 +1476,21 @@ func (r *Cluster) validateWalStorageSize() field.ErrorList {
 	return result
 }
 
+func (r *Cluster) validateEphemeralVolumeSource() field.ErrorList {
+	var result field.ErrorList
+
+	if r.Spec.EphemeralVolumeSource != nil && (r.Spec.EphemeralVolumesSizeLimit != nil &&
+		r.Spec.EphemeralVolumesSizeLimit.TemporaryData != nil) {
+		result = append(result, field.Duplicate(
+			field.NewPath("spec", "ephemeralVolumeSource"),
+			"Conflicting settings: provide either ephemeralVolumeSource "+
+				"or ephemeralVolumesSizeLimit.TemporaryData, not both.",
+		))
+	}
+
+	return result
+}
+
 func (r *Cluster) validateTablespaceStorageSize() field.ErrorList {
 	if r.Spec.Tablespaces == nil {
 		return nil

diff --git a/api/v1/cluster_webhook_test.go b/api/v1/cluster_webhook_test.go
@@ -2842,6 +2842,62 @@ var _ = Describe("Storage configuration validation", func() {
 	})
 })
 
+var _ = Describe("Ephemeral volume configuration validation", func() {
+	It("succeeds if no ephemeral configuration is present", func() {
+		cluster := Cluster{
+			Spec: ClusterSpec{},
+		}
+		Expect(cluster.validateEphemeralVolumeSource()).To(BeEmpty())
+	})
+
+	It("succeeds if ephemeralVolumeSource is set", func() {
+		cluster := Cluster{
+			Spec: ClusterSpec{
+				EphemeralVolumeSource: &corev1.EphemeralVolumeSource{},
+			},
+		}
+		Expect(cluster.validateEphemeralVolumeSource()).To(BeEmpty())
+	})
+
+	It("succeeds if ephemeralVolumesSizeLimit.temporaryData is set", func() {
+		onegi := resource.MustParse("1Gi")
+		cluster := Cluster{
+			Spec: ClusterSpec{
+				EphemeralVolumesSizeLimit: &EphemeralVolumesSizeLimitConfiguration{
+					TemporaryData: &onegi,
+				},
+			},
+		}
+		Expect(cluster.validateEphemeralVolumeSource()).To(BeEmpty())
+	})
+
+	It("succeeds if ephemeralVolumeSource and ephemeralVolumesSizeLimit.shm are set", func() {
+		onegi := resource.MustParse("1Gi")
+		cluster := Cluster{
+			Spec: ClusterSpec{
+				EphemeralVolumeSource: &corev1.EphemeralVolumeSource{},
+				EphemeralVolumesSizeLimit: &EphemeralVolumesSizeLimitConfiguration{
+					Shm: &onegi,
+				},
+			},
+		}
+		Expect(cluster.validateEphemeralVolumeSource()).To(BeEmpty())
+	})
+
+	It("produces one error if conflicting ephemeral storage options are set", func() {
+		onegi := resource.MustParse("1Gi")
+		cluster := Cluster{
+			Spec: ClusterSpec{
+				EphemeralVolumeSource: &corev1.EphemeralVolumeSource{},
+				EphemeralVolumesSizeLimit: &EphemeralVolumesSizeLimitConfiguration{
+					TemporaryData: &onegi,
+				},
+			},
+		}
+		Expect(cluster.validateEphemeralVolumeSource()).To(HaveLen(1))
+	})
+})
+
 var _ = Describe("Role management validation", func() {
 	It("should succeed if there is no management stanza", func() {
 		cluster := Cluster{

diff --git a/api/v1/zz_generated.deepcopy.go b/api/v1/zz_generated.deepcopy.go
diff --git a/config/crd/bases/postgresql.cnpg.io_clusters.yaml b/config/crd/bases/postgresql.cnpg.io_clusters.yaml
diff --git a/docs/src/cloudnative-pg.v1.md b/docs/src/cloudnative-pg.v1.md
@@ -1523,6 +1523,13 @@ user by setting it to <code>NULL</code>. Disabled by default.</p>
    <p>Configuration of the storage for PostgreSQL WAL (Write-Ahead Log)</p>
 </td>
 </tr>
+<tr><td><code>ephemeralVolumeSource</code><br/>
+<a href="https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.28/#ephemeralvolumesource-v1-core"><i>core/v1.EphemeralVolumeSource</i></a>
+</td>
+<td>
+   <p>EphemeralVolumeSource allows the user to configure the source of ephemeral volumes.</p>
+</td>
+</tr>
 <tr><td><code>startDelay</code><br/>
 <i>int32</i>
 </td>

diff --git a/docs/src/cluster_conf.md b/docs/src/cluster_conf.md
@@ -47,11 +47,32 @@ 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. You can configure an upper
-bound on the size using the `.spec.ephemeralVolumesSizeLimit.temporaryData`
-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.
+
+In the following example, a `1Gi` ephemeral volume is set.
+
+```yaml
+apiVersion: postgresql.cnpg.io/v1
+kind: Cluster
+metadata:
+  name: cluster-example-ephemeral-volume-source
+spec:
+  instances: 3
+  ephemeralVolumeSource:
+    volumeClaimTemplate:
+      spec:
+        accessModes: ["ReadWriteOnce"]
+        # example storageClassName, replace with one existing in your Kubernetes cluster
+        storageClassName: "scratch-storage-class"
+        resources:
+          requests:
+            storage: 1Gi
+```
+
+Both `.spec.emphemeralVolumeSource` and `.spec.ephemeralVolumesSizeLimit.temporaryData` cannot be specified simultaneously.
 
 ### Volume for shared memory
 

diff --git a/pkg/specs/volumes.go b/pkg/specs/volumes.go
@@ -98,14 +98,7 @@ func createPostgresVolumes(cluster apiv1.Cluster, podName string) []corev1.Volum
 				},
 			},
 		},
-		{
-			Name: "scratch-data",
-			VolumeSource: corev1.VolumeSource{
-				EmptyDir: &corev1.EmptyDirVolumeSource{
-					SizeLimit: cluster.Spec.EphemeralVolumesSizeLimit.GetTemporaryDataLimit(),
-				},
-			},
-		},
+		createEphemeralVolume(cluster),
 		{
 			Name: "shm",
 			VolumeSource: corev1.VolumeSource{
@@ -325,6 +318,21 @@ func getSortedTablespaceList(cluster apiv1.Cluster) []string {
 	return tbsNames
 }
 
+func createEphemeralVolume(cluster apiv1.Cluster) corev1.Volume {
+	scratchVolumeSource := corev1.VolumeSource{}
+	if cluster.Spec.EphemeralVolumeSource != nil {
+		scratchVolumeSource.Ephemeral = cluster.Spec.EphemeralVolumeSource
+	} else {
+		scratchVolumeSource.EmptyDir = &corev1.EmptyDirVolumeSource{
+			SizeLimit: cluster.Spec.EphemeralVolumesSizeLimit.GetTemporaryDataLimit(),
+		}
+	}
+	return corev1.Volume{
+		Name:         "scratch-data",
+		VolumeSource: scratchVolumeSource,
+	}
+}
+
 func createProjectedVolume(cluster apiv1.Cluster) corev1.Volume {
 	return corev1.Volume{
 		Name: "projected",

diff --git a/pkg/specs/volumes_test.go b/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))
+	})
+})