Build Linux libzim on Bionic

[rgaudin]

I know you just switched from Bionic to focal; with good reasons I believe but it has some unfortunate consequence for python-libzim distribution.

Binary python packages that are not pure python are tied to a platform that helps package managers (pip) pick the appropriate file for an installation.

This notion of platform is somewhat flexible. In Linux, it defaults to linux but can be set more specifically to announce (and should respect) libc-compatibility. There are thus manylinux_1, manylinux_2010, manylinux_2014, and now it's clearer with manylinux_2_28 and the likes.

PEP600 states that a wheel tagged manylinux_x_y shall work on any distro based on glibc>=x.y

It's recommended to use them of course as the package manager can detect an incompatible platform while using linux, your user could install a non-compat one and crash at runtime.

For pylibzim, we've been incorrectly setting the platform as manylinux1 (glic 2.5) while we were building on Focal (glibc 2.31). That's bad 🫣

Now that we have a better building process, we'd like to fix that as well but it's not possible:

• libzim is built on focal (glibc 2.31)
• manylinux project doesn't provide an image for building on 2.31. Latest they propose if 2.28

This leaves us with the following choice:

• A. Build for linux.
  • Mostly work as our users are on 2.31+
  • Prevents us from running the symbols check in the CI
  • Prevents us from automaticly testing the wheels in the CI (tests are ran in another workflow though)
• B. Create a manylinux-like image with 2.31+
  • It's a lot of work
• C. Wait for manylinux to distribute a 2.31+ image
  • No idea about when that could be.

Hence this ticket. With a bionic-built libzim, we could properly set manylinux_2_28.

[kelson42]

OK, then lets make a special release for libzim using bionic... in addition to the normal one using focal.

[rgaudin]

Same issue for macOS as well. Given we now build libzim on macOS12, we can only offer pylibzim for macOS12+.

macOS audience for pylibzim is different than Linux (mostly developers) so we could require most recent systems.
Given the main constraint being the Github Workflow runner, I propose to stick to the earliest supported macos version on github. That would be macos-11. macos-10.15 is still present but deprecated and should have been removed 6m ago.

It seems this environment variable isn't sufficient in current builds as we produce libs that are 12.0.0+.

kiwix-build/kiwixbuild/platforms/ios.py

Lines 70 to 75 in 5bb67d7

	def get_env(self):
	env = super().get_env()
	env['MACOSX_DEPLOYMENT_TARGET'] = '10.15'
	return env

I'll look into logs and open a ticket if I can figure it out