(Backend): Snapshot rpc wrapper functions for frontend-backend link

backend/kale/rpc/snapshot.py

@@ -0,0 +1,50 @@
+#  Copyright 2019-2020 The Kale Authors
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+import logging
+
+from kale.common import podutils, snapshotutils
+from kale.rpc.errors import (RPCServiceUnavailableError)
+from kale.rpc.log import create_adapter
+
+
+logger = create_adapter(logging.getLogger(__name__))
+
+
+def check_snapshot_availability(request):
+    """Check if snapshotclasses are available for notebook."""
+    log = request.log if hasattr(request, "log") else logger
+    try:
+        podutils.check_snapshot_availability()
+    except Exception:
+        log.exception("No snapshotclass is available for this notebook")
+        raise RPCServiceUnavailableError(details=("No snapshotclass"
+                                                  " is available for"
+                                                  " this notebook"),
+                                         trans_id=request.trans_id)
+
+
+def check_snapshot_status(request, snapshot_name):
+    """Check if volume snapshot is ready to use."""
+    return snapshotutils.check_snapshot_status(snapshot_name)
+
+
+def snapshot_notebook(request):
+    """Take snapshots of the current Notebook's PVCs and store its metadata."""
+    return snapshotutils.snapshot_notebook()
+
+
+def replace_cloned_volumes(request, volume_mounts):
+    """Replace the volumes with the volumes restored from the snapshot."""
+    return snapshotutils.replace_cloned_volumes(volume_mounts)