dulwich: provide helpful error when auth fails #8654
Description
Related to #7670
When auth fails for dulwich operations, dvc returns a generic error:
$ dvc get https://github.com/dberenbaum/example-get-started-cp.git README.md
ERROR: failed to get 'README.md' from 'https://github.com/dberenbaum/example-get-started-cp.git' - Failed to clone repo 'https://github.com/dberenbaum/example-get-started-cp.git' to '/var/folders/24/99_tf1xj3vx8k1k_jkdmnhq00000gn/T/tmpzbwy_libdvc-clone'
There is a more helpful error returned by dulwich that specifies that no valid credentials were provided:
$ dvc get -v https://github.com/dberenbaum/example-get-started-cp.git README.md
2022-12-02 14:45:27,662 DEBUG: Creating external repo https://github.com/dberenbaum/example-get-started-cp.git@None
2022-12-02 14:45:27,662 DEBUG: erepo: git clone 'https://github.com/dberenbaum/example-get-started-cp.git' to a temporary dir
2022-12-02 14:45:27,968 DEBUG: Removing '/private/tmp/.UrQfM9Ga9PDxHUwWT3AtEQ'
2022-12-02 14:45:27,968 ERROR: failed to get 'README.md' from 'https://github.com/dberenbaum/example-get-started-cp.git' - Failed to clone repo 'https://github.com/dberenbaum/example-get-started-cp.git' to '/var/folders/24/99_tf1xj3vx8k1k_jkdmnhq00000gn/T/tmp49oa9ucwdvc-clone'
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Traceback (most recent call last):
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/scmrepo/git/backend/dulwich/__init__.py", line 200, in clone
repo = clone_from()
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/porcelain.py", line 538, in clone
return client.clone(
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/client.py", line 760, in clone
result = self.fetch(path, target, progress=progress, depth=depth)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/client.py", line 837, in fetch
result = self.fetch_pack(
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/client.py", line 2075, in fetch_pack
refs, server_capabilities, url = self._discover_references(
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/client.py", line 1934, in _discover_references
resp, read = self._http_request(url, headers)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/dulwich/client.py", line 2215, in _http_request
raise HTTPUnauthorized(resp.getheader("WWW-Authenticate"), url)
dulwich.client.HTTPUnauthorized: No valid credentials provided
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/Users/dave/Code/dvc/dvc/scm.py", line 145, in clone
git = Git.clone(url, to_path, progress=pbar.update_git, **kwargs)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/scmrepo/git/__init__.py", line 143, in clone
backend.clone(url, to_path, **kwargs)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/scmrepo/git/backend/dulwich/__init__.py", line 203, in clone
raise CloneError(url, to_path) from exc
scmrepo.exceptions.CloneError: Failed to clone repo 'https://github.com/dberenbaum/example-get-started-cp.git' to '/var/folders/24/99_tf1xj3vx8k1k_jkdmnhq00000gn/T/tmp49oa9ucwdvc-clone'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/Users/dave/Code/dvc/dvc/commands/get.py", line 39, in _get_file_from_repo
Repo.get(
File "/Users/dave/Code/dvc/dvc/repo/get.py", line 50, in get
with external_repo(
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/contextlib.py", line 135, in __enter__
return next(self.gen)
File "/Users/dave/Code/dvc/dvc/external_repo.py", line 39, in external_repo
path = _cached_clone(url, rev, for_write=for_write)
File "/Users/dave/Code/dvc/dvc/external_repo.py", line 169, in _cached_clone
clone_path, shallow = _clone_default_branch(url, rev, for_write=for_write)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/funcy/decorators.py", line 45, in wrapper
return deco(call, *dargs, **dkwargs)
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/funcy/flow.py", line 274, in wrap_with
return call()
File "/Users/dave/miniforge3/envs/dvc/lib/python3.10/site-packages/funcy/decorators.py", line 66, in __call__
return self._func(*self._args, **self._kwargs)
File "/Users/dave/Code/dvc/dvc/external_repo.py", line 239, in _clone_default_branch
git = clone(url, clone_path)
File "/Users/dave/Code/dvc/dvc/scm.py", line 150, in clone
raise CloneError(str(exc))
dvc.scm.CloneError: Failed to clone repo 'https://github.com/dberenbaum/example-get-started-cp.git' to '/var/folders/24/99_tf1xj3vx8k1k_jkdmnhq00000gn/T/tmp49oa9ucwdvc-clone'
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2022-12-02 14:45:27,985 DEBUG: Analytics is disabled.
It would help to return that error and mention that credentials must be either provided in the url or stored somewhere that they can be retrieved by git.