Migrating from pytz to dateutil.tz + zoneinfo

[Miro Hrončok]

Hello fellow serpents.

I'm one of the Python maintainers in Fedora and RHEL.

I've noticed anaconda-core uses the third party pytz module to work with TZ 
(timzone) data. Since Python 3.9, there is a zoneinfo module in the Python 
standard library:

https://docs.python.org/3/library/zoneinfo.html
https://www.python.org/dev/peps/pep-0615/

Hence we would like to:

- deprecate pytz in Fedora
- avoid pytz in RHEL 10+

Since anaconda is one of the "important" dependents on pytz from both Fedora and 
RHEL, I'm reaching out to you in advance. Could you please consider migrating to 
zoneinfo?

I have not done any such migrations yes, so I don't have any useful links or 
pointers. However, if you'd be interested I can try with anaconda myself.

Note that I don't know if anaconda code from the default branch at 
https://github.com/rhinstaller/anaconda needs to support older Pythons or not. 
If needed, I can try to make the changes more universal.

Let me know if you need some more info, a patch, or just time to handle it 
yourselves.

Thanks,
(Please CC me in replies to the list, I don't receive the usual list traffic.)

[Martin Kolman]

On Thu, 2021-02-11 at 10:14 +0100, Miro Hrončok wrote:
> Hello fellow serpents.
>
> I'm one of the Python maintainers in Fedora and RHEL.
>
> I've noticed anaconda-core uses the third party pytz module to work with TZ 
> (timzone) data. Since Python 3.9, there is a zoneinfo module in the Python 
> standard library:
>
> https://docs.python.org/3/library/zoneinfo.html
> https://www.python.org/dev/peps/pep-0615/
>
> Hence we would like to:
> deprecate pytz in Fedora
> avoid pytz in RHEL 10+

Sounds like a good idea. :)

We did some of these migrations in the past, IIRC for some IP address handling code
for example from a third party library to new stdlib module.
> Since anaconda is one of the "important" dependents on pytz from both Fedora and 
> RHEL, I'm reaching out to you in advance. Could you please consider migrating to 
> zoneinfo?
>
> I have not done any such migrations yes, so I don't have any useful links or 
> pointers. However, if you'd be interested I can try with anaconda myself.

That would be much appreciated!
> Note that I don't know if anaconda code from the default branch at 
> https://github.com/rhinstaller/anaconda needs to support older Pythons or not. 
> If needed, I can try to make the changes more universal.

Older Python support is only needed in the existing RHEL branches for RHEL 7 & 8.

In the default branch we don't support older (<3.9) Python versions.
> Let me know if you need some more info, a patch, or just time to handle it 
> yourselves.

A patch will be the best - and I'm standing by to provide support in all relevant things
Anaconda so just ping me on IRC or send me an email if you have any questions about or codebase,
how to test changes to it, etc. :)
> Thanks,
> (Please CC me in replies to the list, I don't receive the usual list traffic.)

Done. :)

[Miro Hrončok]

On 12. 02. 21 13:02, Martin Kolman wrote:
> On Thu, 2021-02-11 at 10:14 +0100, Miro Hrončok wrote:
> > Hello fellow serpents.
> >
> > I'm one of the Python maintainers in Fedora and RHEL.
> >
> > I've noticed anaconda-core uses the third party pytz module to work with TZ
> > (timzone) data. Since Python 3.9, there is a zoneinfo module in the Python
> > standard library:
> >
> > https://docs.python.org/3/library/zoneinfo.html
> > https://www.python.org/dev/peps/pep-0615/
> >
> > Hence we would like to:
> > deprecate pytz in Fedora
> > avoid pytz in RHEL 10+
>
> Sounds like a good idea. :)
>
> We did some of these migrations in the past, IIRC for some IP address handling code
> for example from a third party library to new stdlib module.
> > Since anaconda is one of the "important" dependents on pytz from both Fedora and
> > RHEL, I'm reaching out to you in advance. Could you please consider migrating to
> > zoneinfo?
> >
> > I have not done any such migrations yes, so I don't have any useful links or
> > pointers. However, if you'd be interested I can try with anaconda myself.
>
> That would be much appreciated!
> > Note that I don't know if anaconda code from the default branch at
> > https://github.com/rhinstaller/anaconda needs to support older Pythons or not.
> > If needed, I can try to make the changes more universal.
>
> Older Python support is only needed in the existing RHEL branches for RHEL 7 & 8.
>
> In the default branch we don't support older (<3.9) Python versions.
> > Let me know if you need some more info, a patch, or just time to handle it
> > yourselves.
>
> A patch will be the best - and I'm standing by to provide support in all relevant things
> Anaconda so just ping me on IRC or send me an email if you have any questions about or codebase,
> how to test changes to it, etc. :)

Thanks Martin, for your welcoming reply.

I've drafted https://github.com/rhinstaller/anaconda/pull/3167

As you can see, I've already realized it's not going to be simple :D

Let's continue the discussion there?