Add a new indexer for matching Pod ClaimNames to PVCs. When deleting …

…a PVC, verify that no Pods match this index search

CHANGELOG.md

@@ -11,6 +11,8 @@ Changelog for Cass Operator, new PRs should update the `main / unreleased` secti
 
 ## unreleased
 
+* [ENHANCEMENT] [#737](https://github.com/k8ssandra/cass-operator/issues/737) Before issuing PVC deletion when deleting a datacenter, verify the PVCs that match the labels are not actually used by any pods.
+
 ## v1.23.0
 
 * [CHANGE] [#720](https://github.com/k8ssandra/cass-operator/issues/720) Always use ObjectMeta.Name for the PodDisruptionBudget resource name, not the DatacenterName

cmd/main.go

@@ -26,11 +26,13 @@ import (
 	"go.uber.org/zap/zapcore"
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 
+	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/healthz"
 	"sigs.k8s.io/controller-runtime/pkg/log/zap"
 
@@ -119,6 +121,8 @@ func main() {
 		os.Exit(1)
 	}
 
+	ctx := ctrl.SetupSignalHandler()
+
 	if err = (&controllers.CassandraDatacenterReconciler{
 		Client:   mgr.GetClient(),
 		Log:      ctrl.Log.WithName("controllers").WithName("CassandraDatacenter"),
@@ -143,6 +147,24 @@ func main() {
 		os.Exit(1)
 	}
 
+	if err := mgr.GetFieldIndexer().IndexField(ctx, &corev1.Pod{}, "spec.volumes.persistentVolumeClaim.claimName", func(obj client.Object) []string {
+		pod, ok := obj.(*corev1.Pod)
+		if !ok {
+			return nil
+		}
+
+		var pvcNames []string
+		for _, volume := range pod.Spec.Volumes {
+			if volume.PersistentVolumeClaim != nil {
+				pvcNames = append(pvcNames, volume.PersistentVolumeClaim.ClaimName)
+			}
+		}
+		return pvcNames
+	}); err != nil {
+		setupLog.Error(err, "unable to set up field indexer")
+		os.Exit(1)
+	}
+
 	if err := mgr.AddHealthzCheck("healthz", healthz.Ping); err != nil {
 		setupLog.Error(err, "unable to set up health check")
 		os.Exit(1)
@@ -153,7 +175,7 @@ func main() {
 	}
 
 	setupLog.Info("starting manager")
-	if err := mgr.Start(ctrl.SetupSignalHandler()); err != nil {
+	if err := mgr.Start(ctx); err != nil {
 		setupLog.Error(err, "problem running manager")
 		os.Exit(1)
 	}

pkg/reconciliation/reconcile_datacenter.go

@@ -13,6 +13,7 @@ import (
 	storagev1 "k8s.io/api/storage/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/fields"
 	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
 	"sigs.k8s.io/controller-runtime/pkg/client"
@@ -125,6 +126,14 @@ func (rc *ReconciliationContext) deletePVCs() error {
 		"numPVCs", len(persistentVolumeClaimList))
 
 	for _, pvc := range persistentVolumeClaimList {
+
+		if isBeingUsed, err := rc.isBeingUsed(pvc); err != nil {
+			logger.Error(err, "Failed to check if PVC is being used")
+			return err
+		} else if isBeingUsed {
+			return fmt.Errorf("PersistentVolumeClaim %s is still being used by a pod", pvc.Name)
+		}
+
 		if err := rc.Client.Delete(rc.Ctx, &pvc); err != nil {
 			logger.Error(err, "Failed to delete PVCs for cassandraDatacenter")
 			return err
@@ -138,6 +147,19 @@ func (rc *ReconciliationContext) deletePVCs() error {
 	return nil
 }
 
+func (rc *ReconciliationContext) isBeingUsed(pvc corev1.PersistentVolumeClaim) (bool, error) {
+	rc.ReqLogger.Info("reconciler::isBeingUsed")
+
+	pods := &corev1.PodList{}
+
+	if err := rc.Client.List(rc.Ctx, pods, &client.ListOptions{Namespace: pvc.Namespace, FieldSelector: fields.SelectorFromSet(fields.Set{"spec.volumes.persistentVolumeClaim.claimName": pvc.Name})}); err != nil {
+		rc.ReqLogger.Error(err, "error getting pods for pvc", "pvc", pvc.Name)
+		return false, err
+	}
+
+	return len(pods.Items) > 0, nil
+}
+
 func (rc *ReconciliationContext) listPVCs(selector map[string]string) ([]corev1.PersistentVolumeClaim, error) {
 	rc.ReqLogger.Info("reconciler::listPVCs")
 

pkg/reconciliation/reconcile_datacenter_test.go

@@ -5,18 +5,20 @@ package reconciliation
 
 import (
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
-	v1 "k8s.io/api/core/v1"
+	corev1 "k8s.io/api/core/v1"
 	storagev1 "k8s.io/api/storage/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/utils/ptr"
+	"sigs.k8s.io/controller-runtime/pkg/client"
 
 	"github.com/k8ssandra/cass-operator/pkg/mocks"
 )
@@ -30,13 +32,23 @@ func TestDeletePVCs(t *testing.T) {
 
 	k8sMockClientList(mockClient, nil).
 		Run(func(args mock.Arguments) {
-			arg := args.Get(1).(*v1.PersistentVolumeClaimList)
-			arg.Items = []v1.PersistentVolumeClaim{{
+			_, ok := args.Get(1).(*corev1.PodList)
+			if ok {
+				if strings.HasPrefix(args.Get(2).(*client.ListOptions).FieldSelector.String(), "spec.volumes.persistentVolumeClaim.claimName") {
+					arg := args.Get(1).(*corev1.PodList)
+					arg.Items = []corev1.Pod{}
+				} else {
+					t.Fail()
+				}
+				return
+			}
+			arg := args.Get(1).(*corev1.PersistentVolumeClaimList)
+			arg.Items = []corev1.PersistentVolumeClaim{{
 				ObjectMeta: metav1.ObjectMeta{
 					Name: "pvc-1",
 				},
 			}}
-		})
+		}).Twice()
 
 	k8sMockClientDelete(mockClient, nil)
 
@@ -55,8 +67,8 @@ func TestDeletePVCs_FailedToList(t *testing.T) {
 
 	k8sMockClientList(mockClient, fmt.Errorf("failed to list PVCs for CassandraDatacenter")).
 		Run(func(args mock.Arguments) {
-			arg := args.Get(1).(*v1.PersistentVolumeClaimList)
-			arg.Items = []v1.PersistentVolumeClaim{{
+			arg := args.Get(1).(*corev1.PersistentVolumeClaimList)
+			arg.Items = []corev1.PersistentVolumeClaim{{
 				ObjectMeta: metav1.ObjectMeta{
 					Name: "pvc-1",
 				},
@@ -73,24 +85,22 @@ func TestDeletePVCs_FailedToList(t *testing.T) {
 func TestDeletePVCs_PVCsNotFound(t *testing.T) {
 	rc, _, cleanupMockScr := setupTest()
 	defer cleanupMockScr()
+	assert := assert.New(t)
 
 	mockClient := mocks.NewClient(t)
 	rc.Client = mockClient
 
 	k8sMockClientList(mockClient, errors.NewNotFound(schema.GroupResource{}, "name")).
 		Run(func(args mock.Arguments) {
-			arg := args.Get(1).(*v1.PersistentVolumeClaimList)
-			arg.Items = []v1.PersistentVolumeClaim{{
+			arg := args.Get(1).(*corev1.PersistentVolumeClaimList)
+			arg.Items = []corev1.PersistentVolumeClaim{{
 				ObjectMeta: metav1.ObjectMeta{
 					Name: "pvc-1",
 				},
 			}}
 		})
 
-	err := rc.deletePVCs()
-	if err != nil {
-		t.Fatalf("deletePVCs should not have failed")
-	}
+	assert.NoError(rc.deletePVCs())
 }
 
 func TestDeletePVCs_FailedToDelete(t *testing.T) {
@@ -102,13 +112,23 @@ func TestDeletePVCs_FailedToDelete(t *testing.T) {
 
 	k8sMockClientList(mockClient, nil).
 		Run(func(args mock.Arguments) {
-			arg := args.Get(1).(*v1.PersistentVolumeClaimList)
-			arg.Items = []v1.PersistentVolumeClaim{{
+			_, ok := args.Get(1).(*corev1.PodList)
+			if ok {
+				if strings.HasPrefix(args.Get(2).(*client.ListOptions).FieldSelector.String(), "spec.volumes.persistentVolumeClaim.claimName") {
+					arg := args.Get(1).(*corev1.PodList)
+					arg.Items = []corev1.Pod{}
+				} else {
+					t.Fail()
+				}
+				return
+			}
+			arg := args.Get(1).(*corev1.PersistentVolumeClaimList)
+			arg.Items = []corev1.PersistentVolumeClaim{{
 				ObjectMeta: metav1.ObjectMeta{
 					Name: "pvc-1",
 				},
 			}}
-		})
+		}).Twice()
 
 	k8sMockClientDelete(mockClient, fmt.Errorf("failed to delete"))
 
@@ -120,6 +140,45 @@ func TestDeletePVCs_FailedToDelete(t *testing.T) {
 	assert.EqualError(t, err, "failed to delete")
 }
 
+func TestDeletePVCs_FailedToDeleteBeingUsed(t *testing.T) {
+	rc, _, cleanupMockScr := setupTest()
+	defer cleanupMockScr()
+	assert := assert.New(t)
+
+	mockClient := mocks.NewClient(t)
+	rc.Client = mockClient
+
+	k8sMockClientList(mockClient, nil).
+		Run(func(args mock.Arguments) {
+			_, ok := args.Get(1).(*corev1.PodList)
+			if ok {
+				if strings.HasPrefix(args.Get(2).(*client.ListOptions).FieldSelector.String(), "spec.volumes.persistentVolumeClaim.claimName") {
+					arg := args.Get(1).(*corev1.PodList)
+					arg.Items = []corev1.Pod{
+						{
+							ObjectMeta: metav1.ObjectMeta{
+								Name: "pod-1",
+							},
+						},
+					}
+				} else {
+					t.Fail()
+				}
+				return
+			}
+			arg := args.Get(1).(*corev1.PersistentVolumeClaimList)
+			arg.Items = []corev1.PersistentVolumeClaim{{
+				ObjectMeta: metav1.ObjectMeta{
+					Name: "pvc-1",
+				},
+			}}
+		}).Twice()
+
+	err := rc.deletePVCs()
+	assert.Error(err)
+	assert.EqualError(err, "PersistentVolumeClaim pvc-1 is still being used by a pod")
+}
+
 func TestStorageExpansionNils(t *testing.T) {
 	rc, _, cleanupMockScr := setupTest()
 	defer cleanupMockScr()