Sunsetting Python 2 astronomy packages
Dear all,
as it turned out recently [1,2], supporting Python 2 packages will get
more difficult now. Specifically, the pytest version that is now in
Debian (3.10) is incompatible to many of our Python 2 packages (or
buggy), making their test suites fail. Pytest upstream will not release
a bugfix version that will bring compatibility back, and Astropy
upstream decided that the Python 2 legacy package (Astropy 2.x) will not
be compatible to newer Pytest versions.
Leaving Astropy 2.x in Debian without continious integration tests would
have the high risk that something breaks undetected when a dependency is
updated. This makes the package unsuitable for scientific work.
To keep our quality standards high, I think it is the best to remove
Astropy 2.x as the Python 2 legacy package from Debian. This will be
accompanied with the removal of all Python 2 packages that depend on
Astropy, namely:
- python-aplpy,
- python-astlib,
- python-astroml,
- python-astroplan,
- python-astropy-healpix,
- python-astroquery,
- python-astroscrappy,
- python-ccdproc,
- python-ginga,
- python-glue,
- python-healpy,
- python-imexam,
- python-montage-wrapper,
- python-pyavm,
- python-pydl,
- python-pymoc,
- python-pyraf,
- python-pyregion,
- python-pysynphot,
- python-cpl,
- python-drizzle,
- python-pyvo,
- python-radio-beam,
- python-reproject,
- python-spectral-cube,
- python-specutils,
- python-stsci.tools,
- python-sunpy.
All these packages have Python 3 versions as well, so nothing is
lost. The migration of the last package that was built on top of Python
2 (astrometry.net) is just started.
This basically means that we will not have a substantial Python 2
astronomy suport in Debian Buster, which will released next year. Keep
in mind however, that End Of Life for Python 2 is April, 2020, and for
Astropy 2.x it is already November, 2019.
Please think carefully about the consequences, and raise your hand soon
if you disagree and are willing to put your efforts in keeping Python 2
astronomy in Debian Buster. Otherwise, I will start to open bug reports
to remove the mentioned packages in ~ 2 weeks.
Best
Ole
[1] https://lists.debian.org/debian-astro/2018/11/msg00010.html
[2] https://github.com/astropy/astropy/pull/8173
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