Dvc: "AttributeError: NoneType object has no attribute 'wdir'" on dvc get-url call

[nickdelgrosso]

Bug Report

When calling dvc get-url gdrive://{mylink} from the command line, I am getting the following AttributeError: "NoneType' object has no attribute 'wdir'. The full traceback is below.

I'm calling dvc get-url from outside the .dvc working directory. A quick look at the source code suggests that this is related to output.LocalOutput being initialized with stage=None from the dependency.loads_from() function in repo.get_url.py.

Please provide information about your setup

Output of dvc version:

$ dvc version
DVC version: 0.94.0
Python version: 3.7.6
Platform: Windows-10-10.0.18362-SP0
Binary: False
Package: pip
Supported remotes: gdrive, http, https
Filesystem type (workspace): ('NTFS', 'C:\\')

Additional Information (if any):

Traceback (most recent call last):
  File "d:\miniconda3\lib\site-packages\dvc\main.py", line 49, in main
    ret = cmd.run()
  File "d:\miniconda3\lib\site-packages\dvc\command\get_url.py", line 17, in run
    Repo.get_url(self.args.url, out=self.args.out)
  File "d:\miniconda3\lib\site-packages\dvc\repo\get_url.py", line 17, in get_url
    (dep,) = dependency.loads_from(None, [url])
  File "d:\miniconda3\lib\site-packages\dvc\dependency\__init__.py", line 83, in loads_from
    ret.append(_get(stage, s, info))
  File "d:\miniconda3\lib\site-packages\dvc\dependency\__init__.py", line 68, in _get
    return LocalDependency(stage, p, info)
  File "d:\miniconda3\lib\site-packages\dvc\output\local.py", line 25, in __init__
    super().__init__(stage, path, *args, **kwargs)
  File "d:\miniconda3\lib\site-packages\dvc\output\base.py", line 98, in __init__
    self.path_info = self._parse_path(remote, path)
  File "d:\miniconda3\lib\site-packages\dvc\output\local.py", line 40, in _parse_path
    p = self.stage.wdir / p
AttributeError: 'NoneType' object has no attribute 'wdir'

[skshetry]

Hi, @nickdelgrosso. Gdrive currently does not support get-url, and hence tries to fallback to LocalDependency.

[efiop]

We should definitely handle it better though. Same ugly error is showing up when you dvc get-url local-non-existent-file. We def need to look into it.

Btw, support for gdrive will be coming along in the nearest future. We are waiting for https://github.com/iterative/PyDrive2/pull/39. So stay tuned :slightly_smiling_face:

[efiop]

@nickdelgrosso To solve it for now, we could simply check if stage in https://github.com/iterative/dvc/blob/master/dvc/output/local.py#L38 and assume that wdir is . otherwise. That would be in-line with https://github.com/iterative/dvc/blob/master/dvc/output/local.py#L20 . Could also pass a dummy stage in get-url instead, but that's probably the easiest way to solve it that is consisent with existing assumptions. Maybe you'd like to contribute a fix for this one too :slightly_smiling_face:

[casperdcl]

also to cross-link support for gdrive streaming: #3408

[efiop]

Ok, we need to revisit our download implementation. Currently it is aimed for pull operation, which makes it ignore errors and just log them and return int code. Our tree.download should raise properly instead. And should properly translate cloud-specific errors into OSErrors. E.g. missing file should make download raise FileNotFoundError. CC @pmrowla , just fyi

[efiop]

This wasn't fixed by #3916. Reopening