Kwallet backend fails in environments where sys.argv is not present

[AndrewGrossman]

Kwallet backend fails in environments where sys does not have argv available.

In my particular case, I was trying to utilize the Snowflake connector for SQLAlchemy through PostgreSQL Multicorn FDW. I encountered the following stacktrace in my log:

  File "/usr/lib/python3/dist-packages/multicorn/sqlalchemyfdw.py", line 282, in __init__
    self.engine = create_engine(url)

  File "/usr/local/lib/python3.6/dist-packages/sqlalchemy/engine/__init__.py", line 500, in create_engine
    return strategy.create(*args, **kwargs)

  File "/usr/local/lib/python3.6/dist-packages/sqlalchemy/engine/strategies.py", line 61, in create
    entrypoint = u._get_entrypoint()

  File "/usr/local/lib/python3.6/dist-packages/sqlalchemy/engine/url.py", line 172, in _get_entrypoint
    cls = registry.load(name)

  File "/usr/local/lib/python3.6/dist-packages/sqlalchemy/util/langhelpers.py", line 265, in load
    return impl.load()

  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2324, in load
    return self.resolve()

  File "/usr/lib/python3/dist-packages/pkg_resources/__init__.py", line 2330, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)

  File "/usr/local/lib/python3.6/dist-packages/snowflake/sqlalchemy/__init__.py", line 8, in <module>
    from . import snowdialect

  File "/usr/local/lib/python3.6/dist-packages/snowflake/sqlalchemy/snowdialect.py", line 27, in <module>
    from snowflake.connector.constants import UTF8

  File "/usr/local/lib/python3.6/dist-packages/snowflake/connector/__init__.py", line 17, in <module>
    from .connection import SnowflakeConnection

  File "/usr/local/lib/python3.6/dist-packages/snowflake/connector/connection.py", line 18, in <module>
    from .auth import Auth

  File "/usr/local/lib/python3.6/dist-packages/snowflake/connector/auth.py", line 51, in <module>
    import keyring

  File "/usr/lib/python3/dist-packages/keyring/__init__.py", line 3, in <module>
    from .core import (set_keyring, get_keyring, set_password, get_password,

  File "/usr/lib/python3/dist-packages/keyring/core.py", line 153, in <module>
    init_backend()

  File "/usr/lib/python3/dist-packages/keyring/core.py", line 66, in init_backend
    keyrings = filter(limit, backend.get_all_keyring())

  File "/usr/lib/python3/dist-packages/keyring/util/__init__.py", line 21, in wrapper
    func.always_returns = func(*args, **kwargs)

  File "/usr/lib/python3/dist-packages/keyring/backend.py", line 184, in get_all_keyring
    _load_backends()

  File "/usr/lib/python3/dist-packages/keyring/backend.py", line 142, in _load_backends
    list(map(_load_backend, backends))

  File "/usr/lib/python3/dist-packages/keyring/backend.py", line 133, in _load_backend
    mod = importlib.import_module('.' + name, package)

  File "/usr/lib/python3.6/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)

  File "/usr/lib/python3/dist-packages/keyring/backends/kwallet.py", line 21, in <module>
    class DBusKeyring(KeyringBackend):

  File "/usr/lib/python3/dist-packages/keyring/backends/kwallet.py", line 26, in DBusKeyring
    appid = os.path.basename(sys.argv[0]) or 'Python keyring library'

AttributeError: module 'sys' has no attribute 'argv'

I was able to successfully work around this by setting sys.argv to [''] when absent.

[sezna]

I had the same issue running Python from pio3. I just submitted PR #447 to fix this.

[jaraco]

It seems to me you've found a bug in those Python implementations. Even the docs of Python reference sys.argv[0]. I'd recommend reporting these non-compliant implementations or updating the Python docs to describe what interface users can expect.

[AndrewGrossman]

I don't think it's necessarily a matter of the Python implementation. Looking at the discussion on https://bugs.python.org/issue839151 and an example usage in a C++ interface at https://stackoverflow.com/questions/12230210/attributeerror-module-object-has-no-attribute-argv-when-using-python-h , it's not clear to me that Python defines the presence of argv as canonical. The interface provides for it and the linked docs seem to be but a simplified general usage example. Yes, I agree that the docs should probably note this.

For my particular use case, I'm looking at CPython via Postgres plpython code at https://github.com/postgres/postgres/blob/master/src/pl/plpython/plpy_main.c

I think there's a valid argument that a script name in that context isn't appropriate and that CPython within Postgresql isn't that cornery of a corner case.

[jaraco]

Thanks for that additional evidence. I've filed bpo-41615 to track the issue upstream. In the meantime, I agree it would be worthwhile to address this issue in keyring.