AdditionalVolumes to allow VolumeSource (#487)

* Allow AdditionalVolumes to be sourced from a VolumeSource and not just PVCSpec. Also, change PVCSpec to a pointer in the AdditionalVolume

* Fix webhook_test

* Add the actual implementation

CHANGELOG.md

@@ -16,7 +16,9 @@ Changelog for Cass Operator, new PRs should update the `main / unreleased` secti
 * [CHANGE] [#448](https://github.com/k8ssandra/cass-operator/issues/448) Update to operator-sdk 1.25.1, update to go 1.19, update to Kubernetes 1.25, remove amd64 restriction on local builds (cass-operator and system-logger will be built for aarch64 also)
 * [CHANGE] [#442](https://github.com/k8ssandra/cass-operator/issues/442) Deprecate old internode-encryption storage mounts and cert generation. If old path /etc/encryption/node.jks is no longer present, then the storage mount is no longer created. For certificates with internode-encryption, we recommend using cert-manager.
 * [CHANGE] [#329](https://github.com/k8ssandra/cass-operator/issues/329) Thrift port is no longer open for Cassandra 4.x installations
+* [CHANGE] [#487](https://github.com/k8ssandra/cass-operator/pull/487) The AdditionalVolumes.PVCSpec is now a pointer. Also, webhook will allow modifying AdditionalVolumes. 
 * [FEATURE] [#441](https://github.com/k8ssandra/cass-operator/issues/441) Implement a CassandraTask for moving single-token nodes
+* [ENHANCEMENT] [#486](https://github.com/k8ssandra/cass-operator/issues/486) AdditionalVolumes accepts VolumeSource as the data also, allowing ConfigMap/Secret/etc to be mounted to cassandra container.
 * [ENHANCEMENT] [#467](https://github.com/k8ssandra/cass-operator/issues/467) Add new metrics endpoint port (9000) to Cassandra container. This is used by the new mgmt-api /metrics endpoint. 
 * [ENHANCEMENT] [#457](https://github.com/k8ssandra/cass-operator/issues/362) Allow overriding the datacenter name
 * [ENHANCEMENT] [#476](https://github.com/k8ssandra/cass-operator/issues/476) Enable CDC for DSE deployments.

apis/cassandra/v1beta1/cassandradatacenter_types.go

@@ -272,11 +272,16 @@ type DseWorkloads struct {
 type AdditionalVolumes struct {
 	// Mount path into cassandra container
 	MountPath string `json:"mountPath"`
-	// Name of the pvc
+
+	// Name of the pvc / volume
 	// +kubebuilder:validation:Pattern=[a-z0-9]([-a-z0-9]*[a-z0-9])?
 	Name string `json:"name"`
-	// Persistent volume claim spec
-	PVCSpec corev1.PersistentVolumeClaimSpec `json:"pvcSpec"`
+
+	// PVCSpec is a persistent volume claim spec. Either this or VolumeSource is required.
+	PVCSpec *corev1.PersistentVolumeClaimSpec `json:"pvcSpec,omitempty"`
+
+	// VolumeSource to mount the volume from (such as ConfigMap / Secret). This or PVCSpec is required.
+	VolumeSource *corev1.VolumeSource `json:"volumeSource,omitempty"`
 }
 
 type AdditionalVolumesSlice []AdditionalVolumes

apis/cassandra/v1beta1/cassandradatacenter_webhook.go

@@ -123,6 +123,10 @@ func ValidateSingleDatacenter(dc CassandraDatacenter) error {
 		return err
 	}
 
+	if err := ValidateAdditionalVolumes(dc); err != nil {
+		return err
+	}
+
 	return ValidateFQLConfig(dc)
 }
 
@@ -150,9 +154,16 @@ func ValidateDatacenterFieldChanges(oldDc CassandraDatacenter, newDc CassandraDa
 		return attemptedTo("change serviceAccount")
 	}
 
-	// StorageConfig changes are disallowed
-	if !reflect.DeepEqual(oldDc.Spec.StorageConfig, newDc.Spec.StorageConfig) {
-		return attemptedTo("change storageConfig")
+	// CassandraDataVolumeClaimSpec changes are disallowed
+
+	if !reflect.DeepEqual(oldDc.Spec.StorageConfig.CassandraDataVolumeClaimSpec, newDc.Spec.StorageConfig.CassandraDataVolumeClaimSpec) {
+		return attemptedTo("change storageConfig.CassandraDataVolumeClaimSpec")
+	}
+
+	if oldDc.Spec.StorageConfig.CassandraDataVolumeClaimSpec != nil {
+		if !reflect.DeepEqual(*oldDc.Spec.StorageConfig.CassandraDataVolumeClaimSpec, *newDc.Spec.StorageConfig.CassandraDataVolumeClaimSpec) {
+			return attemptedTo("change storageConfig.CassandraDataVolumeClaimSpec")
+		}
 	}
 
 	// Topology changes - Racks
@@ -218,6 +229,20 @@ func ValidateDeprecatedFieldUsage(dc CassandraDatacenter) error {
 	return nil
 }
 
+func ValidateAdditionalVolumes(dc CassandraDatacenter) error {
+	for _, volume := range dc.Spec.StorageConfig.AdditionalVolumes {
+		if volume.PVCSpec != nil && volume.VolumeSource != nil {
+			return attemptedTo("create a volume with both PVCSpec and VolumeSource")
+		}
+
+		if volume.PVCSpec == nil && volume.VolumeSource == nil {
+			return attemptedTo("create AdditionalVolume without PVCSpec or VolumeSource")
+		}
+	}
+
+	return nil
+}
+
 // +kubebuilder:webhook:path=/validate-cassandra-datastax-com-v1beta1-cassandradatacenter,mutating=false,failurePolicy=ignore,sideEffects=None,groups=cassandra.datastax.com,resources=cassandradatacenters,verbs=create;update,versions=v1beta1,name=vcassandradatacenter.kb.io,admissionReviewVersions={v1,v1beta1}
 // +kubebuilder:webhook:path=/validate-cassandradatacenter,mutating=false,failurePolicy=ignore,groups=cassandra.datastax.com,resources=cassandradatacenters,verbs=create;update,versions=v1beta1,name=validate-cassandradatacenter-webhook
 var _ webhook.Validator = &CassandraDatacenter{}

apis/cassandra/v1beta1/webhook_test.go

@@ -488,7 +488,7 @@ func Test_ValidateDatacenterFieldChanges(t *testing.T) {
 					},
 				},
 			},
-			errString: "change storageConfig",
+			errString: "change storageConfig.CassandraDataVolumeClaimSpec",
 		},
 		{
 			name: "Removing a rack",