Re: [RFC PATCH v3 00/20] configure: create a python venv and ensure meson, sphinx

["Daniel P. Berrangé" <berrange@redhat.com>]

On Mon, Apr 24, 2023 at 04:02:28PM -0400, John Snow wrote:
> GitLab CI: https://gitlab.com/jsnow/qemu/-/pipelines/846869409
>            (All green, except Python self-tests, see below)
> 
> This patch series creates a mandatory python virtual environment
> ("venv") during configure time and uses it to ensure the availability of
> meson and sphinx.
> 
> See https://www.qemu.org/2023/03/24/python/ for details. The summary is
> that the goal of this series is to ensure that the `python` used to run
> meson is the same `python` used to run Sphinx, tests, and any build-time
> python scripting we have. As it stands, meson and sphinx (and their
> extensions) *may* run in a different python environment than the one
> configured and chosen by the user at configure/build time.
> 
> The effective change of this series is that QEMU will now
> unconditionally create a venv at configure-time and will ensure that
> meson (and sphinx, if docs are enabled) are available through that venv.
> 
> Some important points as a pre-emptive "FAQ":
> 
> - This venv is unconditionally created and lives at {build_dir}/pyvenv.
> 
> - The python interpreter used by this venv is always the one identified
>   by configure. (Which in turn is always the one specified by --python
>   or $PYTHON)
> 
> - *almost* all python scripts in qemu.git executed as part of the build
>   system, meson, sphinx, avocado tests, vm tests or CI are always
>   executed within this venv.
> 
>   (iotests are not yet integrated; I plan to tackle this separately as a
>   follow-up in order to have a more tightly focused scope on that
>   series.)
> 
> - It remains possible to build and test fully offline.
>   (In most cases, you just need meson and sphinx from your distro's repo.)
> 
> - Distribution packaged 'meson' and 'sphinx' are still utilized whenever
>   possible as the highest preference.
> 
> - Vendored versions of e.g. 'meson' are always preferred to PyPI
>   versions for speed, repeatability and ensuring tarball builds work
>   as-is offline.
> 
>   (Sphinx will not be vendored, just like it already isn't.)
> 
> - Missing dependencies, when possible, are fetched and installed
>   on-demand automatically to make developer environments "just work".
> 
> - Works for Python 3.7 and up, on Fedora, OpenSuSE, Red Hat, CentOS,
>   Alpine, Debian, Ubuntu, NetBSD, OpenBSD, and hopefully everywhere
> 
> - No new dependencies (...for most platforms. Debian and NetBSD get an
>   asterisk.)
> 
> - The meson git submodule is unused after this series and can be removed.
> 
> For reviewers, here's how the series is broken up:
> 
> Patch 1 is a testing pre-req. Note that even with this patch,
> 'check-python-minreqs' and 'check-python-tox' CI jobs will both still
> fail on origin/master because this series requires 3.7+, but
> origin/master is currently still 3.6+.
> 
> - python: update pylint configuration
> 
> Patches 2-8 add the mkvenv script. The first patch checks in the barest
> essentials, and each subsequent patch adds a workaround or feature one
> at a time.
> 
> - python: add mkvenv.py
> - mkvenv: add console script entry point generation
> - mkvenv: Add better error message for missing pyexapt module
> - mkvenv: generate console entry shims from inside the venv
> - mkvenv: work around broken pip installations on Debian 10
> - mkvenv: add nested venv workaround
> - mkvenv: add ensure subcommand
> 
> Patches 9-11 modify our testing configuration to add new dependencies as
> needed.
> 
> - tests/docker: add python3-venv dependency
> - tests/vm: Configure netbsd to use Python 3.10
> - tests/vm: add py310-expat to NetBSD
> 
> Patch 12 changes how we package release tarballs.
> 
> - scripts/make-release: download meson==0.61.5 .whl
> 
> Patches 13-16 wire mkvenv into configure and tests.
> 
> - configure: create a python venv unconditionally
> - configure: use 'mkvenv ensure meson' to bootstrap meson
> - configure: add --enable-pypi and --disable-pypi
> - tests: Use configure-provided pyvenv for tests
> 
> Patches 17-20 delegate Sphinx bootstrapping to mkvenv. Some of these
> changes could be folded earlier in the series (like the diagnose()
> patch), but I'm keeping it separate for review for now.
> 
> - configure: move --enable-docs and --disable-docs back to configure
> - mkvenv: add diagnose() method for ensure() failures
> - configure: use --diagnose option with meson ensure
> - configure: bootstrap sphinx with mkvenv

I'm not sure this last bit is working.

I uninstalled meson and python3-sphinx from my F38 host and ran
configure --target-list=x86_64-softmmu and got this:

$ ./configure --target-list=x86_64-softmmu
Using './build' as the directory for build output
python determined to be '/usr/bin/python3'
python version: Python 3.11.3
MKVENV pyvenv
Configured python as '/home/berrange/src/virt/qemu/build/pyvenv/bin/python3 -B'
MKVENV ensure meson>=0.61.5
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
WARNING: Location 'file:///home/berrange/src/virt/qemu/python/wheels' is ignored: it is neither a file nor a directory.
ERROR: Could not find a version that satisfies the requirement meson>=0.61.5 (from versions: none)
ERROR: No matching distribution found for meson>=0.61.5
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
MKVENV ensure sphinx>=1.6.0
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
WARNING: Skipping /usr/lib/python3.11/site-packages/virt_firmware-1.5-py3.11.egg-info due to invalid metadata entry 'name'
ERROR: Could not find a version that satisfies the requirement sphinx>=1.6.0 (from versions: none)
ERROR: No matching distribution found for sphinx>=1.6.0

*** Ouch! ***

Could not ensure availability of 'sphinx>=1.6.0':
 • Python package 'sphinx' was not found nor installed.
 • No local package directory was searched.
 • mkvenv was configured to operate offline and did not check PyPI. 


Sphinx not found/usable, disabling docs.
MKVENV ok!



It says mkvenv was configured to run offline, but I didn't do
anything. I thought the intention was for developers it would
live download from PyPI ?


On a system where i already have meson/sphinx installed, it
all just worked fine AFAICT.

With regards,
Daniel
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