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

[Daniel P . Berrangé]

On Tue, Apr 25, 2023 at 01:34:52PM -0400, John Snow wrote:
> On Tue, Apr 25, 2023, 1:22 PM John Snow <jsnow@redhat.com> wrote:
> 
> >
> >
> > On Tue, Apr 25, 2023, 1:17 PM Daniel P. Berrangé <berrange@redhat.com>
> > wrote:
> >
> >> 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 ?
> >>
> >
> > Ah. So... with enable pypi being the default and with docs set to "auto",
> > I actually fall back to not installing sphinx from pypi *by default*. It
> > tries to locate it on your system and will enable docs if it can, but it
> > doesn't try too hard and doesn't get upset if it fails.
> >
> 
> (Though all of those errors and warnings sure are noisy for meaning "we
> couldn't find an optional package". mkvenv just doesn't distinguish between
> optional and required right now so it just leaves it to the caller to
> interpret. Any suggestions for improving this?)
> 
> 
> > Try passing --enable-docs to convince the build system you'd really
> > definitely like docs, and it'll force the pypi access.
> >
> 
> I can make it try PyPI in this double-default case too, I was just being
> very conservative about when we tried PyPI - this solution is fairly
> reluctant by design to do it.
> 
> If we all agree that it shouldn't be so reluctant, and anyone who doesnt
> want it at all should just pass --disable-pypi, I can make that change
> easily.
> 
> I wonder if I should make an "auto" setting for the pypi access which
> represents this behavior ("only if I have to"), and make "enable" more
> aggressive (consult pypi even for optional features.)
> 
> I was just being conservative on the first pass. Trying to strike a balance
> between convenience, speed, and least surprise.

How about having --enable-pypi never|auto|force with the following
semantics for --enable-docs + --enable-pypi


  * docs=no   - pypi never used

  * docs=auto + pypi=never  => docs only enable if sphinx is already
                               installed locally, otherwise disabled

  * docs=auto + pypi=auto  => docs enable if sphinx is already
                              installed locally, or can download from
                              pypi as fallback

  * docs=auto + pypi=force  => always download sphinx from pypi


  * docs=yes + pypi=never  => ERROR if sphinx is not already
                              installed locally

  * docs=yes + pypi=auto  => docs enable if sphinx is already
                             installed locally, or can download from
                             pypi as fallback

  * docs=yes + pypi=force  => always download sphinx from pypi



So eg distros could use pypi=never, devs would use pypi=auto mostly,
while CI might use pypi=force to test specific versions indepenant
of distros ?

With regards,
Daniel
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