Install Via pip Fails Due to Dependency scikit-build

[AntumDeluge]

Originally submitted here: ninja-build/ninja#1608

I believe that scikit-build should be added as a dependency in pip install as I get the following error if it is not installed:

$ pip install ninja
Collecting ninja
  Using cached https://files.pythonhosted.org/packages/dd/96/e2ec4acccb8dee33b4987f553d531d61e3081c8d4cfbce249655dfe23906/ninja-1.9.0.post1.tar.gz
    ERROR: Complete output from command python setup.py egg_info:
    ERROR: Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-av7tfuja/ninja/setup.py", line 7, in <module>
        from skbuild import setup
    ModuleNotFoundError: No module named 'skbuild'
    ----------------------------------------
ERROR: Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-install-av7tfuja/ninja/

---

Edit: System & platform information:

OS: Microsoft Windows 10 64-bit
Python & pip info:

$ python --version
Python 3.7.4

$ python -c 'import sys; print("64-bit: {}".format(sys.maxsize > 2**32))'
64-bit: True

$ pip --version
pip 19.1 from /usr/lib/python3.7/site-packages/pip (python 3.7)

$ pip search ninja
ninja (1.9.0.post1)                               - Ninja is a small build
                                                    system with a focus on
                                                    speed
...

[grische]

@jcfr would it be possible to add this dependency?

[jcfr]

since ninja binaries are expected to be available as wheel for all python distributions, it is not expected that we built it from source.

I think we should understand the root cause here.

Indeed, the wheels are expected to work with all python distributions. See https://pypi.org/project/ninja/#files

Using the python interpreter where there are issues, what is the output of the following:

from pip._internal.pep425tags import get_supported
print('\n'.join('-'.join(x) for x in get_supported()))

[grische]

@jcfr I built a very simple testcase for you to reproduce the issue:

1. Create a Dockerfile with the following content

FROM alpine:3.10

# install python3 (incl. pip3)
RUN apk add --no-cache --update python3

# add example file
RUN echo -e "from pip._internal.pep425tags import get_supported\nprint('\\\n'.join('-'.join(x) for x in get_supported()))" > /jcfr_test.py
RUN python3 /jcfr_test.py

# install ninja dependency manually
#RUN pip3 install 'scikit-build==0.10.0'

RUN pip3 install ninja

2. Run docker build --no-cache -t jcfr_test .

This results in

Step 4/5 : RUN python3 /jcfr_test.py
 ---> Running in 59175424ed96
cp37-cp37m-linux_x86_64
cp37-abi3-linux_x86_64
cp37-none-linux_x86_64
cp36-abi3-linux_x86_64
cp35-abi3-linux_x86_64
cp34-abi3-linux_x86_64
cp33-abi3-linux_x86_64
cp32-abi3-linux_x86_64
py3-none-linux_x86_64
cp37-none-any
cp3-none-any
py37-none-any
py3-none-any
py36-none-any
py35-none-any
py34-none-any
py33-none-any
py32-none-any
py31-none-any
py30-none-any
Removing intermediate container 59175424ed96
 ---> 5f0b70a8bc10
Step 5/5 : RUN pip3 install ninja
 ---> Running in 8124dbb4abb5
Collecting ninja
  Downloading https://files.pythonhosted.org/packages/dd/96/e2ec4acccb8dee33b4987f553d531d61e3081c8d4cfbce249655dfe23906/ninja-1.9.0.post1.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-c4xl435b/ninja/setup.py", line 7, in <module>
        from skbuild import setup
    ModuleNotFoundError: No module named 'skbuild'

[grische]

@jcfr is there any change regarding this issue?

[andreparames]

@jcfr

Indeed, the wheels are expected to work with all python distributions.

Unfortunately not: pypa/pip#3969

Unfortunately (this word does come to mind repeatedly when thinking of Python packaging), requiring a build dependency can only be done by adding another file to the source tarball. Example: https://github.com/prody/ProDy/pull/806/files

But that should solve the problem for us alpine users 🙂

[bsolomon1124]

@andreparames can you please clarify what you mean by "that should solve the problem for us alpine users"? Which step are you suggesting solves that problem?

[andreparames]

@bsolomon1124 you have to add a pyproject.toml file to the root of the project (see example linked in my previous comment), with scikit-build in the requires line. That way, it'll fetch that dependency before building ninja.

[mayeut]

Fixed in 1.10.0.post3