pyproject.toml-based builds lose proxy config for build-dependency installation

[mjpieters]

Environment

• pip version: 18.1
• Python version: 3.7.1
• OS: MacOS, Windows

Description

When behind a proxy, installing a project with a pyproject.toml defining a build-system.requires option will fail, because the BuildEnvironment.install_requirements() implementation runs pip as a child process without copying across proxy configuration.

Expected behavior

Even in an isolated build environment, proxy access needs to be configured, so that build dependencies can be downloaded.

How to Reproduce

Block direct access to PyPI, and use a proxy to install pyinstaller, e.g. pip install pyinstaller --proxy=http://webdefence.global.blackspider.com:80 --trusted-host=pypi.python.org.

Disabling build isolation with --no-build-isolation and manually installing the build requirements first lets you work around this issue.

Output

$ pip install pyinstaller --proxy=http://webdefence.global.blackspider.com:80 --trusted-host=pypi.python.org
Collecting pyinstaller
  Using cached https://files.pythonhosted.org/packages/03/32/0e0de593f129bf1d1e77eed562496d154ef4460fd5cecfd78612ef39a0cc/PyInstaller-3.4.tar.gz
  Installing build dependencies ... error
  Complete output from command c:\users\blaggr\appdata\local\programs\python\python37-32\scripts\python.exe -m pip install --ignore-installed --no-user --prefix C:\Users\blaggr\AppData\Local\Temp\pip-build-env-vd3w15r1 --no-warn-script-location --no-binary :none: --only-binary :none: -i https://pypi.org/simple --trusted-host pypi.python.org -- setuptools wheel:
  Collecting setuptools
    Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/setuptools/
    Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/setuptools/
    Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/setuptools/
    Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/setuptools/
    Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/setuptools/
    Could not find a version that satisfies the requirement setuptools (from versions: )
  No matching distribution found for setuptools

I'm filing this ticket as a follow-up to a Stack Overflow question, where a Windows user ran into this problem. They shared their pip -vvv output to help diagnosing.

[pradyunsg]

Thanks for filing this! ^>^

[mjpieters]

This is the same basic issue as #5502, where network configuration switches are not being forwarded to the isolated child process.

[gaborbernat]

I also found out that --no-cache-dir is also not forwarded, or cache dir in general.

[chrisinmtown]

@mjpieters you suggest as a workaround using flag --no-build-isolation. Please say, where/how do I implement that workaround? Forgive my ignorance about .toml files, the section that seems to cause the problem is this one in my case:

[build-system]
requires = ["poetry_core>=1.0", "setuptools"]
build-backend = "poetry.core.masonry.api"

The first build step tries to install these but fails in my proxy-afflicted environment.

[turribeach]

We seem to be affected by this issue but it doesn't seem that it has got any traction, given that it's nearly 4 years old. Any ideas when it will be fixed? Thanks

[uranusjr]

It’d be awesome if you’d be interested in working on it and submit a pull request! Someone being actively affected is in the best position to debug the issue and test the changes.

[turribeach]

I will be happy to test any potential fixes but I got no idea where the problem is and I am not a hardcore Python developer, I just write some occasional Python.

[pfmoore]

To be clear, this is probably going to wait until someone who is affected by the issue (and therefore has an environment that can be used to test potential solutions) can create a PR. None of the pip developers work in an environment where this functionality is needed, so we're dependent on the community for help here.

I'll add the "awaiting PR" label to the issue to reflect the position here.