implement deletion of local snapshots for S3 backups

When creating a remote backup in LINSTOR, we can remove the local snapshot
after shipping completes.

Signed-off-by: Moritz "WanzenBug" Wanzenböck <[email protected]>

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Delete S3 backups in delete snapshot requests.
+- Delete local snapshots when creating S3 backups when new "delete-local" parameter is true.
 
 ## [1.1.1] - 2023-06-05
 

examples/k8s/volume-snapshot-class.yaml

@@ -15,6 +15,8 @@ parameters:
   # See https://linbit.com/drbd-user-guide/linstor-guide-1_0-en/#s-shipping_snapshots-linstor for details
   # on each parameter.
   snap.linstor.csi.linbit.com/remote-name: snapshot-bucket
+  # Delete local copy of the snapshot after uploading completes
+  snap.linstor.csi.linbit.com/delete-local: "true"
   snap.linstor.csi.linbit.com/allow-incremental: "false"
   snap.linstor.csi.linbit.com/s3-bucket: snapshot-bucket
   snap.linstor.csi.linbit.com/s3-endpoint: s3.us-west-1.amazonaws.com

pkg/driver/driver.go

@@ -956,8 +956,21 @@ func (d Driver) CreateSnapshot(ctx context.Context, req *csi.CreateSnapshotReque
 		}).Debug("found existing snapshot")
 
 		if existingSnap.GetSourceVolumeId() == req.GetSourceVolumeId() {
+			err = d.maybeDeleteLocalSnapshot(ctx, existingSnap, params)
+			if err != nil {
+				return nil, status.Errorf(codes.Internal, "failed to delete local snapshot: %s", err)
+			}
+			if existingSnap.ReadyToUse && params.Type != volume.SnapshotTypeInCluster && params.DeleteLocal {
+				// Create a new, local only snapshot object, so we don't accidentally delete the remote backup
+				err := d.Snapshots.SnapDelete(ctx, &volume.Snapshot{Snapshot: existingSnap.Snapshot})
+				if err != nil {
+					return nil, status.Errorf(codes.Internal, "can't delete local snapshot: %s", err)
+				}
+			}
+
 			return &csi.CreateSnapshotResponse{Snapshot: &existingSnap.Snapshot}, nil
 		}
+
 		return nil, status.Errorf(codes.AlreadyExists, "can't use %q for snapshot name for volume %q, snapshot name is in use for volume %q",
 			req.GetName(), req.GetSourceVolumeId(), existingSnap.GetSourceVolumeId())
 	}
@@ -967,6 +980,11 @@ func (d Driver) CreateSnapshot(ctx context.Context, req *csi.CreateSnapshotReque
 		return nil, status.Errorf(codes.Internal, "failed to create snapshot: %v", err)
 	}
 
+	err = d.maybeDeleteLocalSnapshot(ctx, snap, params)
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "failed to delete local snapshot: %s", err)
+	}
+
 	return &csi.CreateSnapshotResponse{Snapshot: &snap.Snapshot}, nil
 }
 
@@ -1348,6 +1366,29 @@ func (d Driver) createNewVolume(ctx context.Context, info *volume.Info, params *
 	}, nil
 }
 
+// maybeDeleteLocalSnapshot deletes the local portion of a snapshot according to their volume.SnapshotParameters.
+// It will not delete a snapshot that is not ready, does not have a remote target, or where local deletion is disabled.
+func (d Driver) maybeDeleteLocalSnapshot(ctx context.Context, snap *volume.Snapshot, params *volume.SnapshotParameters) error {
+	if !snap.ReadyToUse {
+		return nil
+	}
+
+	if params.Type == volume.SnapshotTypeInCluster {
+		return nil
+	}
+
+	if !params.DeleteLocal {
+		return nil
+	}
+
+	err := d.Snapshots.SnapDelete(ctx, &volume.Snapshot{Snapshot: snap.Snapshot})
+	if err != nil {
+		return fmt.Errorf("can't delete local snapshot: %s", err)
+	}
+
+	return nil
+}
+
 func missingAttr(methodCall, volumeID, attr string) error {
 	if volumeID == "" {
 		volumeID = "an unknown volume"

pkg/volume/snapshot_params.go

@@ -24,6 +24,7 @@ type SnapshotParameters struct {
 	Type             SnapshotType `json:"type,omitempty"`
 	AllowIncremental bool         `json:"allow-incremental"`
 	RemoteName       string       `json:"remote-name,omitempty"`
+	DeleteLocal      bool         `json:"delete-local,omitempty"`
 	S3Endpoint       string       `json:"s3-endpoint,omitempty"`
 	S3Bucket         string       `json:"s3-bucket,omitempty"`
 	S3SigningRegion  string       `json:"s3-signing-region,omitempty"`
@@ -51,6 +52,13 @@ func NewSnapshotParameters(params, secrets map[string]string) (*SnapshotParamete
 			}
 
 			p.Type = t
+		case "/delete-local":
+			b, err := strconv.ParseBool(v)
+			if err != nil {
+				return nil, err
+			}
+
+			p.DeleteLocal = b
 		case "/allow-incremental":
 			b, err := strconv.ParseBool(v)
 			if err != nil {
@@ -82,6 +90,10 @@ func NewSnapshotParameters(params, secrets map[string]string) (*SnapshotParamete
 		return nil, fmt.Errorf("snapshots of type `%s` require specifying a %s/remote-name", p.Type, linstor.SnapshotParameterNamespace)
 	}
 
+	if p.Type == SnapshotTypeInCluster && p.DeleteLocal {
+		return nil, fmt.Errorf("cannot use %s/delete-local with in-cluster snapshots", linstor.SnapshotParameterNamespace)
+	}
+
 	p.S3AccessKey = secrets["access-key"]
 	p.S3SecretKey = secrets["secret-key"]