The PDM_OVERRIDE environment variable does not work.

[dairiki]

Synopsis

Using the --override argument to pdm lock to pass a constraint file works, but using the PDM_OVERRIDE environment variable to do the same does not.

• I have searched the issue tracker and believe that this is not a duplicate.

Steps to reproduce

$ pdm init -n
Creating a pyproject.toml for PDM...
INFO: Using the first matched interpreter.
Virtualenv is created successfully at 
[...]/.venv
Project is initialized successfully

# Need at least one dependency.  (I don't think it matters what it is.)
$ pdm add markupsafe

$ touch constraints.txt

# This works:
$ pdm lock --override constraints.txt
Changes are written to pdm.lock.
  0:00:00 🔒 Lock successful. 

# This does not:
$ PDM_OVERRIDE=constraints.txt pdm lock -v
pdm.termui: ======== Start resolving requirements ========
pdm.termui:   markupsafe>=2.1.5
pdm.termui:   Adding requirement markupsafe>=2.1.5
Traceback (most recent call last):
  File "/home/dairiki/.local/bin/pdm", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/core.py", line 351, in main
    return core.main(args or sys.argv[1:])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/core.py", line 269, in main
    raise cast(Exception, err).with_traceback(traceback) from None
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/core.py", line 264, in main
    self.handle(project, options)
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/core.py", line 196, in handle
    command.handle(project, options)
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/cli/commands/lock.py", line 123, in handle
    actions.do_lock(
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/cli/actions.py", line 145, in do_lock
    mapping = _lock_for_env(
              ^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/cli/actions.py", line 189, in _lock_for_env
    mapping, *_ = resolve(
                  ^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/resolver/core.py", line 43, in resolve
    result = resolver.resolve(requirements, max_rounds)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/resolvelib/resolvers.py", line 546, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/resolvelib/resolvers.py", line 397, in resolve
    self._add_to_criteria(self.state.criteria, r, parent=None)
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/resolvelib/resolvers.py", line 173, in _add_to_criteria
    if not criterion.candidates:
           ^^^^^^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/resolvelib/structs.py", line 127, in __bool__
    next(iter(self))
         ^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/resolvelib/structs.py", line 136, in __iter__
    self._factory() if self._iterable is None else self._iterable
    ^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/resolver/providers.py", line 217, in matches_gen
    elif identifier in self.overrides:
                       ^^^^^^^^^^^^^^
  File "/home/dairiki/.pyenv/versions/3.12.3/lib/python3.12/functools.py", line 995, in __get__
    val = self.func(instance)
          ^^^^^^^^^^^^^^^^^^^
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/resolver/providers.py", line 165, in overrides
    parser.parse_file(override_file)
  File "/home/dairiki/.local/share/pdm/venv/lib/python3.12/site-packages/pdm/formats/requirements.py", line 104, in parse_file
    with open(filename_or_url, encoding="utf-8") as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: 'c'

Actual behavior

pdm lock craps out if the PDM_OVERRIDE environment variable is set.

Expected behavior

pdm lock should complete successfully, respecting the constraints specified in the file referenced by PDM_OVERRIDE.

Here's the Issue

The click.Optionargument for the --override option is declared with action="append". This means that, if the --override option is specified on the command line, override will be a list of strings.
This conflicts with the type of the default value for the option, os.getenv("PDM_OVERRIDE"), which is just a string (rather than a sequence of strings).

pdm/src/pdm/cli/options.py

Lines 514 to 521 in d579492

	override_option = Option(
	"--override",
	default=os.getenv("PDM_OVERRIDE"),
	action="append",
	help="Use the constraint file in pip-requirements format for overriding. [env var: PDM_OVERRIDE] "
	"This option can be used multiple times. "
	"See https://pip.pypa.io/en/stable/user_guide/#constraints-files",
	)

PDM interprets override as a sequence of file names of constraint files. When the value comes from PDM_OVERRIDE, interpreting the string as a sequence erroneously results in a series of one-character-long file names.

It's a trivial issue, but I'm unsure of the cleanest fix. Perhaps using click's envvar arg would do the trick? (This would allow the specification of multiple constraint files via PDM_OVERRIDE.)

If you would like, I would be happy to attempt a PR. (But maybe this is simple enough that you'd rather just fix it yourself.) Let me know.

[Edited: Originally, I did not look close enough to realize that the Option class was not a click.Option. ]

Environment Information

# Paste the output of `pdm info && pdm info --env` below:
PDM version:
  2.18.2
Python Interpreter:
  /home/dairiki/git/web/lektor-packages/lektor/junk/.venv/bin/python (3.12)
Project Root:
  /home/dairiki/git/web/lektor-packages/lektor/junk
Local Packages:
  
{
  "implementation_name": "cpython",
  "implementation_version": "3.12.3",
  "os_name": "posix",
  "platform_machine": "x86_64",
  "platform_release": "6.8.0-45-generic",
  "platform_system": "Linux",
  "platform_version": "#45~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Wed Sep 11 15:25:05 UTC 2",
  "python_full_version": "3.12.6",
  "platform_python_implementation": "CPython",
  "python_version": "3.12",
  "sys_platform": "linux"
}

[frostming]

PR welcome

[frostming]

Fixed by e95520e