Linux builds with in-tree downloaded build systems

[nicholasjng]

Hello cibuildwheel community,

I am playing around with Bazel-based wheel builds again, this time it is about Docker-based Linux builds.

The default base manylinux2014 images do not contain a bazel binary, which is completely cool - so far, I grabbed a repo and yum installed bazel in the image using BEFORE_ALL_LINUX.

That Bazel version is however not recent enough for what I am trying to do now, which is using QEMU virtualization to build wheels for different architectures. For my first attempt, I curl the Bazel binary from the Github Bazel releases page, and save it into the {project} tree.

This works for manylinux x86, but when I attempt the first emulated architecture, it fails with a No such file or directory: /project/bazel. A resulting run of this strategy can be found here.

I am passing the path to the binary via an environment variable - the section in my workflow file looks like this:

https://github.com/nicholasjng/benchmark/blob/0f5f4da91268c22c2f29d4ba728c1572d2fca039/.github/workflows/wheels.yml#L60-L63

Any hint to what I am doing wrong here? I am suspecting the download of the binary (x86 every time) could be the culprit, but I am not sure.