[ovirt-devel] [vdsm] Fwd: Tech talk summary: Future of Python in RHEL and Fedora

[Francesco Romani]

Just in case this was somehow missed

----- Forwarded Message -----
> From: "Petr Viktorin" <pviktori at redhat.com>
> To: python-list at redhat.com
> Cc: python-maint at redhat.com, devexp-list at redhat.com, "Nick Coghlan" <ncoghlan at gmail.com>,
> rhel-product-org at redhat.com, rhel-next at redhat.com, "Jan Beran" <jberan at redhat.com>, os-devel-list at redhat.com,
> "Langdon White" <langdon at redhat.com>
> Sent: Friday, May 20, 2016 12:46:11 PM
> Subject: Tech talk summary: Future of Python in RHEL and Fedora
> 
> Hello,
> Miro Hrončok and I have recently given a tech talk on the future of
> Python in RHEL and Fedora. If you didn't catch it, there's a recording
> available at: https://bluejeans.com/s/9EnS/
> 
> If you don't have time to watch, but develop or maintain Python-based
> software in RHEL, please take some time read this summary.
> 
> This is the current plan of the python-maint team, based on various
> discussions. Change requests are welcome.
> 
> 
> ## RHEL ##
> 
> The problems we're trying to solve are:
> - Upstream support for Python 2.x will end in 2020. We do not have
> resources to maintain Python 2 for the full RHEL 8 lifetime.
> - We'd like to avoid locking us and customers to a single Python version
> for the entire RHEL 8 lifetime.
> - Some customers want several versions of Python installed at once.
> 
> Our solution to these problems is to provide two (kinds of) Python
> stacks in RHEL 8:
> - System Python (/usr/bibexec/system-python), on which Red Hat-provided
> software can depend, and which can be upgraded or modified as Red Hat
> needs. This will be Python 3.5.
> - Separately installed Pythons, provided by SCLs or containers (the
> exact implementation should be determined as part of the modularization
> effort). Several of these can be installed at once, and they will have
> their own support lifetimes. The interpreters will be available at
> /usr/bin/pythonX.Y
> 
> Python-based software provided by Red Hat can either use System Python
> (which will be Python 3), or separately installed Pythons (which can be
> any version, but may be supported for a shorter time).
> 
> If you maintain such software, please plan for this. Let us know if you
> need any assistance or additional information. We at python-maint will
> be happy to help (but you do need to ask).
> 
> 
> ## Fedora ##
> 
> In Fedora, a system-python is included since F24, but for a different
> reason: to make cloud images as small as possible.
> Fedora's system-python contains a subset of the standard library, with
> some modules (like those needed for development) removed. The remaining
> pieces are provided by python-libs.
> Packages that care about minimizing their dependency footprint, and
> don't need the excluded modules, can depend on system-python instead of
> the full Python.
> We're planning to start talking to DNF and cloud-init teams to switch to
> system-python.
> 
> 
> ## Python 3 ##
> 
> Python 3.0 was released in 2008, and most active open-source projects
> now either support it or are working on it. Python 3 brings a better
> Unicode model (which, as Nick Coghlan put it, has unfortunately, "broken
> many of the workarounds that had been put in place to deal with the
> limitations of the old model"), and an ever-increasing list of new
> features. Python 2 is legacy software on extended support.
> 
> In Fedora, 44% of packages are ported. Many of the remaining 56% are
> practically abandoned.
> Based on somewhat hand-wavy estimates, 70% of packages that will be
> needed in RHEL are ported. Many of the rest are Red Hat projects.
> 
> Eventually, all Python software will need to be ported to Python 3. If
> you maintain a project that hasn't started yet, it is best not to delay.
> Resources and support are available:
> - Lennart Regebro’s Supporting Python 3: http://python3porting.com
> - RPM Porting Guide (for Fedora spec files):
> http://python-rpm-porting.readthedocs.io/
> - We're also writing a "Conservative Porting Guide" for "laggard"
> projects (hopefully including customers' in-house tools). The plan is to
> release in the summer.
> 
> Let us know if you have any questions, if you need any help porting to
> Python 3, or if you see a bug in our plans!
> 
> 
> --
> Petr Viktorin
> 
> 

-- 
Francesco Romani
RedHat Engineering Virtualization R & D
Phone: 8261328
IRC: fromani