Re: [PATCH] scripts/sphinx-pre-install: add '-p python3' to virtualenv

[Markus Heiser]

Am 04.03.20 um 06:42 schrieb Mauro Carvalho Chehab:
> Em Tue, 3 Mar 2020 17:07:48 +0000
> "Bird, Tim" <Tim.Bird@xxxxxxxx> escreveu:
>
> > > -----Original Message-----
> > > From: Jonathan Corbet <corbet@xxxxxxx>
> > >
> > > On Mon, 24 Feb 2020 18:34:41 -0700
> > > tbird20d@xxxxxxxxx wrote:
> > >    
> > > > With Ubuntu 16.04 (and presumably Debian distros of the same age),
> > > > the instructions for setting up a python virtual environment should
> > > > do so with the python 3 interpreter.  On these older distros, the
> > > > default python (and virtualenv command) might be python2 based.
> > > >
> > > > Some of the packages that sphinx relies on are now only available
> > > > for python3.  If you don't specify the python3 interpreter for
> > > > the virtualenv, you get errors when doing the pip installs for
> > > > various packages
> > > >
> > > > Fix this by adding '-p python3' to the virtualenv recommendation
> > > > line.
> > > >
> > > > Signed-off-by: Tim Bird <tim.bird@xxxxxxxx>
> > >
> > > I've applied this, even though it feels a bit fragile to me.  But Python
> > > stuff can be a bit that way, sometimes, I guess.
> >
> > I agree it seems a bit wonky.
>
> Well, we could, instead, add some code that would be checking python and pip
> versions, but still distros could be doing some backports with could
> cause side-effects. So, checking for distro versions as done in this patch
> seems a lot safer.
>
> > The less fragile approach would have been to just
> > always add the '-p python3' option to the virtualenv setup hint,
> > but Mauro seemed to want something more fine-tuned.
>
> Yeah, I asked for a more fine-tuned version.
>
> Depending on python/pip version, adding a -p python3 seems to cause
> troubles (at least I found some bug reports about that). I may be
> wrong (it was a long time ago), but, before adding the logic that checks
> for "python3" I guess I tried first add -p python3, but, back then,
> I found some troubles (probably with some old Fedora version).
>
> So, better to use this syntax only on distros we know it will
> work as expected.
>
> > As far as the string parsing goes, I think that the format of strings
> > returned by lsb-release (and the predecesors that sphinx_pre_install
> > checks) is unlikely to change.
>
> Since when we added this script, we didn't have any troubles yet with
> the part of the code with checks the distribution version. So, I guess
> that the lsb-release related checks are pretty much reliable.

With py3 the recommended way to install virtual environments is::

  python3 -m venv sphinx-env

This (python3) is what worked for me on RHEL/CentOS (dnf),
archlinux and debian/ubuntu (tested from 16.04 up to 20.04).

I am not familiar with the sphinx-pre-install script but may be
one of you is able to apply such a patch?


 -- Markus --