rbd: implement GetSnapshot CSI procedure

See-also: container-storage-interface/spec#586
Signed-off-by: Niels de Vos <ndevos@ibm.com>

Author: nixpanic

go.mod

@@ -43,6 +43,9 @@ require (
 	k8s.io/utils v0.0.0-20241210054802-24370beab758
 )
 
+// FIXME: for texting https://github.com/container-storage-interface/spec/pull/586
+replace github.com/container-storage-interface/spec => github.com/xing-yang/spec v0.1.1-0.20250423161802-69d15cde6003 // GetSnapshot branch
+
 require (
 	// sigs.k8s.io/controller-runtime wants this version, it gets replaced below
 	k8s.io/client-go v12.0.0+incompatible

go.sum

@@ -159,8 +159,6 @@ github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211001041855-01bcc9b48dfe/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
-github.com/container-storage-interface/spec v1.11.0 h1:H/YKTOeUZwHtyPOr9raR+HgFmGluGCklulxDYxSdVNM=
-github.com/container-storage-interface/spec v1.11.0/go.mod h1:DtUvaQszPml1YJfIK7c00mlv6/g4wNMLanLgiUbKFRI=
 github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/csi-addons/kubernetes-csi-addons v0.12.0 h1:RbF2dCjWV4ljynibEOkA0wbwwt/09awjOKgEFC14Bns=
@@ -652,6 +650,8 @@ github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOf
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/x448/float16 v0.8.4 h1:qLwI1I70+NjRFUR3zs1JPUCgaCXSh3SW62uAKT1mSBM=
 github.com/x448/float16 v0.8.4/go.mod h1:14CWIYCyZA/cWjXOioeEpHeN/83MdbZDRQHoFcYsOfg=
+github.com/xing-yang/spec v0.1.1-0.20250423161802-69d15cde6003 h1:T9DDPr22JY/YzulKhQ5djqKCxAhRmmbxKUHbvZ+r7Ic=
+github.com/xing-yang/spec v0.1.1-0.20250423161802-69d15cde6003/go.mod h1:DtUvaQszPml1YJfIK7c00mlv6/g4wNMLanLgiUbKFRI=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.1.32/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

internal/rbd/controllerserver.go

@@ -1701,3 +1701,27 @@ func (cs *ControllerServer) ControllerUnpublishVolume(
 
 	return &csi.ControllerUnpublishVolumeResponse{}, nil
 }
+
+func (cs *ControllerServer) GetSnapshot(
+	ctx context.Context,
+	req *csi.GetSnapshotRequest,
+) (*csi.GetSnapshotResponse, error) {
+	mgr := NewManager(cs.Driver.GetInstanceID(), nil, req.GetSecrets())
+	defer mgr.Destroy(ctx)
+
+	snapID := req.GetSnapshotId()
+	snapshot, err := mgr.GetSnapshotByID(ctx, snapID)
+	if err != nil {
+		return nil, status.Errorf(codes.NotFound, "failed to find snapshot with ID %q: %s", snapID, err.Error())
+	}
+	defer snapshot.Destroy(ctx)
+
+	csiSnap, err := snapshot.ToCSI(ctx)
+	if err != nil {
+		return nil, status.Error(codes.Internal, err.Error())
+	}
+
+	return &csi.GetSnapshotResponse{
+		Snapshot: csiSnap,
+	}, nil
+}

internal/rbd/driver/driver.go

@@ -112,6 +112,7 @@ func (r *Driver) Run(conf *util.Config) {
 			csi.ControllerServiceCapability_RPC_CREATE_DELETE_SNAPSHOT,
 			csi.ControllerServiceCapability_RPC_CLONE_VOLUME,
 			csi.ControllerServiceCapability_RPC_EXPAND_VOLUME,
+			csi.ControllerServiceCapability_RPC_GET_SNAPSHOT,
 		})
 		// We only support the multi-writer option when using block, but it's a supported capability for the plugin in
 		// general