snapshots and snapshot_metadata directories get deleted when you delete all snapshots #72
Description
To reproduce:
- created two snapshots
- deleted both snapshots
- tried creating another snapshot. Got the error:
Traceback (most recent call last):
File "/Users/jfischer/anaconda3/envs/dws-test-environment/lib/python3.6/site-packages/ipykernel/comm/manager.py", line 111, in comm_msg
comm.handle_msg(msg)
File "/Users/jfischer/anaconda3/envs/dws-test-environment/lib/python3.6/site-packages/ipykernel/comm/comm.py", line 161, in handle_msg
self._msg_callback(msg)
File "/Users/jfischer/code/data-workspaces-core/dataworkspaces/kits/jupyter.py", line 363, in _recv
message=self._snapshot_args.message)
File "/Users/jfischer/code/data-workspaces-core/dataworkspaces/api.py", line 103, in take_snapshot
return snapshot_command(workspace, tag=tag, message=message)
File "/Users/jfischer/code/data-workspaces-core/dataworkspaces/commands/snapshot.py", line 68, in snapshot_command
existing_tag_md = mixin.get_snapshot_by_tag(tag) # type: Optional[SnapshotMetadata]
File "/Users/jfischer/code/data-workspaces-core/dataworkspaces/backends/git.py", line 445, in get_snapshot_by_tag
for fname in os.listdir(md_dir):
FileNotFoundError: [Errno 2] No such file or directory: '/Users/jfischer/code/demo-for-talk/demo/.dataworkspace/snapshot_metadata'
Fix is to either always ensure both directories are present before taking a snapshot or creating a placeholder file when the workspace is created.