What, No Python in RHEL 8 Beta?

https://developers.redhat.com/blog/2018/11/27/what-no-python-in-rhel-8-beta/

88 59 8 years ago

developers.redhat.com

wyldfire2• 8 years ago

In order to improve the experience for RHEL 8 users, we have moved the Python used by the system “off to the side”

This was a good move.

we came to the tough conclusion, don’t provide a default, unversioned Python at all. Ideally, people will get used to explicitly typing python3 or python2.

This seems like a principled stance, one I can agree with. But it's probably one RHEL will suffer for. I think they have a lot of share for the enterprise linux marketplace (maybe #1 or #2?), so maybe they can afford it. RHEL customers should dust off their Python2 source and seriously consider migrating to straddle both 2 and 3 for now. Although the fact that RHEL8 provides ten years of Python 2 support means that they're unlikely to feel that pressure any time soon.

mkesper• 8 years ago

The whole eco system stops caring about Python2. Everybody using Python will suffer if they rely on using Python2 until 2030.

rleigh5• 8 years ago

Unfortunately though, the whole ecosystem hasn't stopped caring, and is unlikely to anytime soon. They should care, but they either don't care or can't migrate quickly enough. Migration can be phenomenally expensive and introduce a ton of bugs. Python 2 will be the IE6 of this era. It's too entrenched to abandon. On the other hand, it will slowly fade into obscurity as migrations occur and old projects die.

This approach is a fair one, which will keep all their customers happy. If you've got complex Python 2 applications deployed on CentOS 7, then this won't be a hindrance to migration. Likewise if you want to drop Python 2 and only deploy with Python 3, they have that covered as well.

All in all, it sounds pragmatic and reasonable, and from the business point of view, they aren't going to lose customers as a result, by having huge blockers to upgrading.

mistrial9• 8 years ago

customers should dust off their Python2 source

Customers will do what they want to do with Python 2.7 code and libraries that work very well right now. The continuous improvement workers are clearly annoyed that Python 2.7 is not broken.

With the right amount of effort, Python 2.7 will continue to work well for the next ten years.

Perl comes to mind here..

rleigh5• 8 years ago

It's going to break horribly in 2020 irrespective of RedHat's efforts.

Earlier this year, one of the projects I maintained started failing on CentOS 6 (Python 2.6). No code changes had been made to account for it. What had happened was that pip/pypi had updated some modules which had dropped Python 2.6 support, and now required Python 2.7. Unfortunately, the package management and dependency information is so rudimentary that pip will happily create an environment which is completely broken, or fails to build due to the scripts being incapable of running with an older interpreter. This completely broke our build.

The same fate lies in wait for Python 2.7. A number of common modules are planning on fully dropping Python 2.7 support come the EOL date. Once they do so, pip will break, and it will not be possible to construct a working environment except by hand. Or using manually packaged modules e.g. from the FreeBSD ports tree or the Debian archive. This will be the death knell for Python 2.7 for practical use and deployment. It will only take a tiny number of critical modules to make the switch for the whole pip/pypi ecosystem to be completely crippled for use with Python 2.7.

maxerickson• 8 years ago

Why would application developers try to straddle 2 and 3?

If they are gonna do the work to support 3, just abandon 2.

Libraries are a different story.

rleigh5• 8 years ago

Usually it's because big projects are a logistical nightmare to migrate. You can't do it in one go. Not only do you have to transition every library plus the applications and tools and tests, you also have to keep it functional, testable and deployable on all the existing python 2 platforms as well.

I'm not saying this is a good way of doing things, simply that it's the practical reality for many codebases. And with tools like python-modernise, it's also eminently achievable. I've managed to do this with several Python codebases, so that they work with either 2 or 3, and in the future we can drop 2 and fully migrate to 3-only features. This allows a smooth, seamless transition with no breakage.

It would definitely be easier if a clean break could be made, and Python 2 support is dropped on the floor, but for many projects this is simply unacceptable.

fragmede• 8 years ago

In order to improve the experience ... yum install python results in a 404.

I'm not convinced the attention is focused on "the experience".

Returning 404 is hardly a user friendly experience, even if the linked blog post (and thus the solution) is trivially Googleable. Maybe an error/informational message with instructions to `yum install python3` or `yum install python2` could be displayed instead?

nine_k• 8 years ago

Yes, yes, and yes.

The rule of (sore) thumb is: never use system Python for anything. Pretend it does not exist (and RH just did). It's there for running system software that happens to use Python interpreter and packages. It should only be managed by the system package / dependency manager.

For anything you write or download as source, explicitly install the right Python version, and create a separate virtualenv / container / whatnot, without any link to system-provided Python packages. It will save you a huge amount of headache.

CoolGuySteve3• 8 years ago

This is such a strange and annoying compromise to make. It's somewhat antithetical to the concept of RHEL versions being a standardized set of packages such that when someone says "I have RHEL 7", you can say "My software will work on that".

Now in order to support RHEL 8, you have to tell them to also have their sys admin install your preferred python.

A better and less bespoke to RHEL solution imo would have been to make an anaconda install or virtualenv the default python for each user.

mavhc• 8 years ago

Wouldn't you just specify the dependencies in your installer so it just works?

CoolGuySteve3• 8 years ago

Most people in my field don't use installers or rpms, we just share the git repo directly. I'm kind of pissed off just thinking about how many build systems will break when '/usr/bin/env python' doesn't return anything by default.

collinmanderson• 8 years ago

My guess is a lot of sysadmins will just end up installing both 2 and 3.

madhadron• 8 years ago

The best solution I am aware of is to package your Python apps statically with the version they expect. For example, Facebook's XAR format (https://github.com/facebookincubator/xar/) does this very nicely.

badsectoracula• 8 years ago

This looks remarkably similar to AppImage (which i suppose can also be used to package your own Python).

PaulHoule• 8 years ago

Woo hoo!

swalsh• 8 years ago

I recently installed OpenSuse tubleweed. I'm not sure if I just had a weird installation, but both python 2.7, and python 3.6 were installed. That's great, but the "pip" command by default was pointed at pip3.6. Imagine how confused I was when I installed a bunch of packages using the "pip" command, but none of them were available from the default "python" shell.

I think the, let's be explicit about what we're installing approach isn't bad.

nitroll• 8 years ago

python3 -m pip install foo

It also works for python2. I try to avoid using python tools that installs their own scripts and go for calling the module through python. This also works for python3/2 -m venv venv

nailer• 8 years ago

Any current Fedora users want to tell me what all the Red Hat tools use? Eg is usr bin banana actually Python 2 or Python 3?

rterzi5• 8 years ago

Fedora at least as of F28, moved to have system tools like dnf use Python 3.

For RHEL 8, the tools included with the system will use a different binary, platform-python that isn't in /usr/bin.

I can't remember if that's also the case for F28/F29.

dralley• 8 years ago

Fedora doesn't ship with any Python 2, all the utilities in the default installation are Python 3.

rterzi5• 8 years ago

"Ship with" is a bit too ambiguous for my taste. F28/F29 "ship with" Python 2 in the sense that the packages are there, just not installed with a default install. If you `dnf install python2` (or something that depends on Python 2.7) it will get installed. They've also gone through the effort and moved the system stuff line dnf to Python 3.

jlgaddis• 8 years ago

Red Hat-specific tools or just all the general system utilities nstalled on a RHEL host? I've got a ThinkPad sitting here running the beta of RHEL 8.

(FWIW, I don't think either is installed by default, but maybe that was something else I installed recently?)

mroche3• 8 years ago

Neither ship by default. If you run a search for libpython you should find one hidden away in a nonstandard location. As far as I’m aware, only core tools necessary for a minimal install rely on it. Other packages in the repos can depend on an actual user space python version.

^ Needs verification

moosingin3space• 8 years ago

On Fedora, there's a system Python interpreter installed at `/usr/libexec/system-python` that is used to run Python tools installed in the base system like `dnf`. On my F29 system, it's version 3.7. You can't install pip packages into the system Python environment, which helps you not break your system, like what can happen if you've ever run `sudo pip install --upgrade pip` on Ubuntu or Debian!

zenlot2• 8 years ago

"However, we do try to make it as easy as possible to get Python 2 or 3 (or both) on to your system." - it just requires quite a long blog post to explain how easy it is.

sli• 8 years ago

Install instructions are right at the top and are typical `yum` commands that RHEL users should already know.

zenlot2• 8 years ago

So RHEL been around for 18 years, and suddendly users need to be aware about the "install instructions", which "are right at the top" and read a blog post about it for RHEL 8?

dade_• 8 years ago

Great move. I recently experienced the whole Ubuntu 16.04 LTS Python 3.5 and 3.6 on my system and it is just plain messy. Yeah, they can co-exist, but now I have 3 versions of Python. How many people didn't know better and have have tried removing 3.5 and completely broke their install and possibly ruined their weekend or evening. It also sends a message. A proper / official way for distributions to deal with this situation is needed.

What, No Python in RHEL 8 Beta?

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