Optionally use existing installations of tools

[altendky]

https://github.com/joerick/cibuildwheel/blob/9372e37b1886be448ca6b67a14dc6708657ac4a8/README.md#L35

It will try to install packages globally; this is no good.

I haven't looked and this isn't any priority for me but... couldn't this installation be optional? I might tend towards having it disabled by default but I get there will be arguments both ways.

[joerick]

Well, on Mac, cibuildwheel installs MacPython, and upgrades setuptools, wheel, delocate globally (not in a virtualenv). On Windows it assumes the existence of the interpreters, but still installs things like pip, setuptools globally.

What would the use-case be for disabling these installs? doing a build/test run on your mac/windows dev machine?

[altendky]

I didn't dig into the details, just read the docs, but yes. As I said this is of no urgency to me but I think software is generally better when it doesn't need warnings like this. Is there some need to install these globally rather than in an env?

[joerick]

Is there some need to install these globally rather than in an env?

MacPython can only be installed globally. But other than that, the python bits could install into a venv. I guess that running cibuildwheel locally could be helpful for debugging. In which case, maybe we could have something like cibuildwheel --local, which would look for existing installs of MacPython (or Windows local installs) and use a virtualenv for the python dependencies.

[altendky]

I would tend to default to not trying to fuss with the system. Requiring that people type --install-deps or whatever once in a tox.ini doesn't seem particularly onerous. or even a separate subcommand (are there any? i forget...).

[HDembinski]

I am trying to use cibuildwheels for a non-trivial project, and - of course - it does not work, because I need to install certain dependencies that are missing in some docker images or not found by the CMake scripts in my project. Debugging these issues by adding small commits on a branch until the CI works is an incredibly painful process.

Long story short: it would be great if one could run cibuildwheels locally for testing/debugging of the build.

[YannickJadoul]

Long story short: it would be great if one could run cibuildwheels locally for testing/debugging of the build.

It can be, right? If you're happy to have docker images downloaded and run, or Python versions installed on macOS/Windows, you can perfectly run cibuildwheel locally. Just skip the platform checks/detection by adding the correct --platform flag.
It's just really not meant to run locally, so we're not enabling that by default.

[hoffmang9]

I am trying to use cibuildwheels for a non-trivial project, and - of course - it does not work, because I need to install certain dependencies that are missing in some docker images or not found by the CMake scripts in my project. Debugging these issues by adding small commits on a branch until the CI works is an incredibly painful process.

We had the same issues - the best way to debug the os/cmake problems is to run the pypa docker and get it building by hand there.

Example CIBW_BEFORE_BUILD_LINUX here: https://github.com/Chia-Network/bls-signatures/blob/master/.github/workflows/build.yml