Can not load package data resources when running in a zipapp

[sinoroc]

• OS version and name: Ubuntu Linux 18.04
• Poetry version: 1.0.10 (in a zipapp)
• Python: CPython 3.6.9

Issue

$ poetry config -vvv --list

[ValueError]
Schema poetry-schema does not exist.

Traceback (most recent call last):
  File "/home/sinoroc/.local/bin/poetry/clikit/console_application.py", line 131, in run
    status_code = command.handle(parsed_args, io)
  File "/home/sinoroc/.local/bin/poetry/clikit/api/command/command.py", line 120, in handle
    status_code = self._do_handle(args, io)
  File "/home/sinoroc/.local/bin/poetry/clikit/api/command/command.py", line 171, in _do_handle
    return getattr(handler, handler_method)(args, io, self)
  File "/home/sinoroc/.local/bin/poetry/cleo/commands/command.py", line 92, in wrap_handle
    return self.handle()
  File "/home/sinoroc/.local/bin/poetry/poetry/console/commands/config.py", line 75, in handle
    local_config_file = TomlFile(self.poetry.file.parent / 'poetry.toml')
  File "/home/sinoroc/.local/bin/poetry/poetry/console/commands/command.py", line 10, in poetry
    return self.application.poetry
  File "/home/sinoroc/.local/bin/poetry/poetry/console/application.py", line 49, in poetry
    self._poetry = Factory().create_poetry(Path.cwd())
  File "/home/sinoroc/.local/bin/poetry/poetry/factory.py", line 48, in create_poetry
    check_result = self.validate(local_config)
  File "/home/sinoroc/.local/bin/poetry/poetry/factory.py", line 272, in validate
    validation_errors = validate_object(config, 'poetry-schema')
  File "/home/sinoroc/.local/bin/poetry/poetry/json/__init__.py", line 22, in validate_object
    raise ValueError('Schema {} does not exist.'.format(schema_name))

Culprit is probably this block of code:

# [...]
SCHEMA_DIR = os.path.join(os.path.dirname(__file__), "schemas")

class ValidationError(ValueError):
    pass

def validate_object(obj, schema_name):  # type: (dict, str) -> List[str]
    schema = os.path.join(SCHEMA_DIR, "{}.json".format(schema_name))
   # [...]

Loading resources from package data should be done with pkgutil.get_data() (or importlib-resources or pkg_resources), especially if the code is running directly from a zipped file. These libraries are able to handle zipped resources.

References:

• https://github.com/wimglenn/resources-example
• https://gitlab.com/python-devs/importlib_resources/-/issues/58#note_404347272 -- Meaning support in importlib-resources is now much better since 1.3 and it seems to have been ported into Python 3.9's importlib.resources

[sinoroc]

At least I guess that importlib-resources (or pkg_resources) could help. I will give it a try, and suggest a fix (pull request) if I get something meaningful.

[sinoroc]

• poetry-core-1.0.0rc2

It is not possible to file issues against poetry-core, but basically there is a similar issue in poetry-core as well. Actually in one of its vendored dependencies, namely jsonschema:

$ zapp-poetry config -vvv --list
Traceback (most recent call last):
  File "/usr/lib/python3.8/runpy.py", line 194, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/home/sinoroc/.local/bin/zapp-poetry/__main__.py", line 2, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/console/__init__.py", line 1, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/console/application.py", line 7, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/console/commands/__init__.py", line 4, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/console/commands/check.py", line 1, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/factory.py", line 9, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/core/factory.py", line 13, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/core/json/__init__.py", line 7, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/core/_vendor/jsonschema/__init__.py", line 22, in <module>
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 655, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 618, in _load_backward_compatible
  File "<frozen zipimport>", line 259, in load_module
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/core/_vendor/jsonschema/validators.py", line 446, in <module>
  File "/home/sinoroc/.local/bin/zapp-poetry/poetry/core/_vendor/jsonschema/_utils.py", line 53, in load_schema
NotADirectoryError: [Errno 20] Not a directory: '/home/sinoroc/.local/bin/zapp-poetry/poetry/core/_vendor/jsonschema/schemas/draft3.json'

The culprit lines seem to be the following in poetry-core/vendors/patches/jsonschema.patch:

+    with open(
+        os.path.join(os.path.dirname(__file__), "schemas", "{0}.json".format(name))
+    ) as f:
+        data = f.read()


-    data = pkgutil.get_data("jsonschema", "schemas/{0}.json".format(name))
-    return json.loads(data.decode("utf-8"))
+    return json.loads(data)

Not sure why the patch has been written to replace the call to pkgutil.get_data with something else... A bit strange.

[sinoroc]

Next occurrence is in lark-parser:

https://github.com/lark-parser/lark/blob/0.9.0/lark/lark.py#L347-L362

    def open(cls, grammar_filename, rel_to=None, **options):
        """Create an instance of Lark with the grammar given by its filename
        If rel_to is provided, the function will find the grammar filename in relation to it.
        Example:
            >>> Lark.open("grammar_file.lark", rel_to=__file__, parser="lalr")
            Lark(...)
        """
        if rel_to:
            basepath = os.path.dirname(rel_to)
            grammar_filename = os.path.join(basepath, grammar_filename)
        with open(grammar_filename, encoding='utf8') as f:
            return cls(f, **options)

This would need to be patched (and sent upstream).

[sinoroc]

On the lark front... After investigation, and some further changes to poetry-core, the next blocking issue is about loading lark's standard grammars. Like here for example:

https://github.com/python-poetry/poetry-core/blob/72291f379f87e41e22714f0eff0dbbdf57d9c060/poetry/core/version/grammars/markers.lark#L35-L37

[sinoroc]

I started with pkgutil.get_data() (from the standard library) but I don't know if it is the right decision. If I understood right, there is a wish to deprecate it. It might be a very long time until it happens though.

On the other hand there is importlib.resources, which is part of the standard library starting with Python 3.7. And it is also available as a 3rd party package importlib-resources, for "Python 2.7, and 3.4 through 3.8" since as far as I understood not all features are in 3.7 and 3.8. Seems like starting with 3.9 the backport is not necessary.

Anyway, pkgutil.get_data is quite limited and looks like it won't be enough. There are some cases (with lark for example), where we will need an actual path to a file on the file system.

I would rule out setuptools' pkg_resources for now (mainly because it is not part of the standard library, so it is a great disadvantage compared to the other solutions, it works fine though).

[gpshead]

We just patched our own vendored copy of poetry for this with:

core/spdx/helpers.py:

-    licenses_file = Path(__file__).parent / "data" / "licenses.json"
+    licenses_file = importlib.resources.files("poetry.core.spdx").joinpath("data/licenses.json")

core/json/__init__.py:

 def validate_object(obj: dict[str, Any], schema_name: str) -> list[str]:
-    schema_file = SCHEMA_DIR / f"{schema_name}.json"
-
-    if not schema_file.exists():
-        raise ValueError(f"Schema {schema_name} does not exist.")
+    schema_file = importlib.resources.files("poetry.core.json").joinpath(f"schemas/{schema_name}.json")

While we're running on 3.10 & 3.11, importlib.resources is a 3.7 addition. If you still need to support Python versions older than that, you can use the already mentioned pypi importlib-resources package.

[gpshead]

(those patches appear to belong with the poetry-core repo rather than this one), also it appears the files APIs were introduced in 3.9 (also as noted in sinoroc's comment). An importlib-resources>=1.3 dependency when installing for python<3.9 makes sense. I'll see if I can make reasonable PR(s) in the correct repos for all of this.

[gpshead]

someone who understands the needs of the project should take over my PR.

[Secrus]

If anyone wants to test the solution, I have made #10074 and python-poetry/poetry-core#819.

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