来自 alpine 软件包存储库的 Numpy 无法导入 c 扩展

我正在制作一个需要 pandas 和 numpy 的 docker 映像，但通过 pip 安装大约需要 20 分钟，这对于我的用例来说太长了。然后我选择从 alpine 软件包存储库安装 pandas 和 numpy，但似乎无法正确导入 numpy。

这是我的 Dockerfile：

# syntax=docker/dockerfile:experimental
FROM python:3.9.5-alpine as base

FROM base as builder
RUN apk add build-base gcc musl-dev

RUN --mount=type=cache,target=/root/.cache/pip \
    pip install --target="/install" django

FROM base
RUN apk add py3-pandas py3-numpy

COPY --from=builder /install /usr/local/lib/python3.9/site-packages

ENV PYTHONPATH "${PYTHONPATH}:/usr/lib/python3.9/site-packages"

CMD ["python"]

当我尝试导入依赖于 numpy 的 pandas 时，出现错误：

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/site-packages/pandas/__init__.py", line 16, in <module>
    raise ImportError(
ImportError: Unable to import required dependencies:
numpy: 

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the numpy C-extensions failed. This error can happen for
many reasons, often due to issues with your setup or how NumPy was
installed.

We have compiled some common reasons and troubleshooting tips at:

    https://numpy.org/devdocs/user/troubleshooting-importerror.html

Please note and check the following:

  * The Python version is: Python3.9 from "/usr/local/bin/python"
  * The NumPy version is: "1.20.3"

and make sure that they are the versions you expect.
Please carefully study the documentation linked above for further help.

Original error was: No module named 'numpy.core._multiarray_umath'

如果我导入 numpy 会出现错误：

Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/numpy/core/__init__.py", line 22, in <module>
    from . import multiarray
  File "/usr/lib/python3.9/site-packages/numpy/core/multiarray.py", line 12, in <module>
    from . import overrides
  File "/usr/lib/python3.9/site-packages/numpy/core/overrides.py", line 7, in <module>
    from numpy.core._multiarray_umath import (
ModuleNotFoundError: No module named 'numpy.core._multiarray_umath'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.9/site-packages/numpy/__init__.py", line 145, in <module>
    from . import core
  File "/usr/lib/python3.9/site-packages/numpy/core/__init__.py", line 48, in <module>
    raise ImportError(msg)
ImportError: 

IMPORTANT: PLEASE READ THIS FOR ADVICE ON HOW TO SOLVE THIS ISSUE!

Importing the numpy C-extensions failed. This error can happen for
many reasons, often due to issues with your setup or how NumPy was
installed.

We have compiled some common reasons and troubleshooting tips at:

    https://numpy.org/devdocs/user/troubleshooting-importerror.html

Please note and check the following:

  * The Python version is: Python3.9 from "/usr/local/bin/python"
  * The NumPy version is: "1.20.3"

and make sure that they are the versions you expect.
Please carefully study the documentation linked above for further help.

Original error was: No module named 'numpy.core._multiarray_umath'

我已经束手无策，试图找出我错过了什么和做错了什么。我已经尝试了错误跟踪给出的 url 中的故障排除提示，但似乎没有解决问题。

任何帮助是极大的赞赏。

我知道自从有人提出这个问题以来已经有一段时间了，您可能已经找到了解决方案，或者从 Alpine 转移到了另一个发行版。但我遇到了同样的问题，这是我搜索中出现的第一件事。因此，在花了几个小时找到解决方案之后，我认为值得在这里记录下来。

问题（显然）是numpy and pandas包。我使用了社区存储库中的预制轮子，并遇到了与您相同的问题。因此，显然，构建过程本身就引入了这个问题。具体来说，如果您查看，例如，在numpy/core在安装位置（/usr/lib/python3.9/site-packages），你会发现所有的 C 扩展都有.cpython-39-x86_64-linux-musl以他们的名义。例如，您遇到问题的模块，numpy.core._multiarray_umath， 被命名_multiarray_umath.cpython-39-x86_64-linux-musl.so，而且不仅仅是_multiarray_umath.so。丢弃.cpython-39-x86_64-linux-musl从这些文件名修复了问题（编辑：有关详细信息，请参阅附录）。

可以将以下行添加到您的Dockerfile安装后py3-pandas and py3-numpy要解决这个问题：

RUN find /usr/lib/python3.9/site-packages -iname "*.so" -exec sh -c 'x="{}"; mv "$x" "${x/cpython-39-x86_64-linux-musl./}"' \;

P.S.：在进一步研究这个问题之后，我找到了罪魁祸首：出于某种原因，在 Alpine 下运行的 Python 认为它的完整平台扩展后缀（可从importlib.machinery.EXTENSION_SUFFIXES） 应该cpython-39-x86_64-linux-gnu.so， 并不是cpython-39-x86_64-linux-musl.so。我不相信它是用 glibc 构建的，但谁知道呢。所以，你可以改变musl to gnu在上面那些共享对象的名称中，它也可以工作。不知道为什么构建期间生成的扩展后缀与 Python 在运行时使用的扩展后缀不同。