Pure python3 for the AD DC for Samba 4.10 (5.0) (was: Re: WAF 2.x upgrade for 4.10)

[Andrew Bartlett]

On Thu, 2018-08-02 at 22:45 +0200, Stefan Metzmacher wrote:
> Am 02.08.2018 um 22:21 schrieb Andrew Bartlett via samba-technical:
> > On Thu, 2018-08-02 at 21:02 +0100, Noel Power wrote:
> > > 4)
> > > 
> > >   PYTHON=/usr/bin/python3 python3 ./buildtools/bin/waf [FAILS]
> > > 
> > > fails with
> > > 
> > > "ERROR: grouping library target
> > > pytalloc-util.cpython-36m-x86_64-linux-gnu not declared in
> > > samba_python.cpython-36m-x86_64-linux-gnu"
> > > 
> > > I haven't tried to get to the bottom of this yet, waf scares me :0
> > > 
> > > But I think this is a configuration (as in wbuild) problem because a
> > > python3 build (using detected python lib version 2.7 works fine)
> > 
> > Noel,
> > 
> > Can you strip out all the extra python stuff and try again?  We seem to
> > be on the way to a rough consensus of py3 only for 4.10 and that would
> > greatly simplify everything.
> 
> I'm not for python3 only. I think setups with the primary python as 2.7
> and extra python being python3 should keep working.
> At least pure python2.7 or python3 should work.

For fileserver builds --without-python, sure, long-term python 2.7
support is reasonable to request.   

I have no issue with the waf build still operating on python 2.7. 

For the AD DC, we can't afford the maintaince burden to try and keep it
all working with both, we need to cut over and just write Samba's
'python' in a single language, not the dumbed down combination that
happens to be mostly compatible with the two distinct languages
'python2' and 'python3'.  

This follows the strongest advise I got from python experts when we
started this endeavour: to migate, then cut ties with python2 as soon
as possible.  

Even if we make every 'python' test operate with py3_compatible=True,
we won't fully test python3, because binaries like smbtorture (which
invoke python) won't be built against python3, and the provision
scripts run in the environment setup won't be run as python3.  Other
tests are destructive (the demote tests) so can't be run twice. 

Therefore, the --extra-python code in our build system, while helpful
during development, is actually incredible painful for packagers and
hindrance to Samba long-term.  It, as has been seen here, just gets in
the way of a pure python3 build.  

As only real test would be a full ./configure with pure python3, and
while possible I suggest adding another whole duplicate to autobuild
would be absurd, we should just move to the AD DC build being with
python3 only.  

We should push hard and finish this!

(There are actually some really nice python3 features that we could use
once we get there). 

Thanks,

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba