“python_requires” should be set with “>=3.6”, as horizon 21.0.0 is not compatible with all Python versions.

[pyvcechecker]

Currently, the keyword argument "python_requires" of "setup()" is not set, and thus it is assumed that this distribution is compatible with all Python versions.
However, I found it is not compatible with "Python <3.6". My local Python version is 3.5, and I encounter the following error when executing "pip install horizon"

------
Collecting horizon
  Downloading horizon-21.0.0-py3-none-any.whl (5.1 MB)
     |████████████████████████████████| 5.1 MB 465 kB/s
Collecting python-keystoneclient>=3.22.0
  Downloading python_keystoneclient-3.22.0-py2.py3-none-any.whl (397 kB)
     |████████████████████████████████| 397 kB 444 kB/s
Collecting oslo.upgradecheck>=0.1.1
  Downloading oslo.upgradecheck-0.4.0-py2.py3-none-any.whl (11 kB)
ERROR: Could not find a version that satisfies the requirement oslo.i18n>=5.0.1 (from horizon) (from versions: 0.1.0, 0.2.0, 0.3.0, 0.4.0, 1.0.0, 1.1.0, 1.2.0, 1.3.0, 1.3.1, 1.4.0, 1.5.0, 1.6.0, 1.7.0, 2.0.0, 2.1.0, 2.2.0, 2.3.0, 2.4.0, 2.5.0, 2.6.0, 2.7.0, 3.0.0, 3.1.0, 3.2.0, 3.3.0, 3.4.0, 3.5.0, 3.6.0, 3.7.0, 3.8.0, 3.9.0, 3.10.0, 3.11.0, 3.12.0, 3.13.0, 3.14.0, 3.15.0, 3.15.1, 3.15.2, 3.15.3, 3.16.0, 3.17.0, 3.17.1, 3.17.2, 3.18.0, 3.19.0, 3.20.0, 3.21.0, 3.22.0, 3.22.1, 3.23.0, 3.23.1, 3.24.0, 3.25.0, 3.25.1)
ERROR: No matching distribution found for oslo.i18n>=5.0.1 (from horizon)
------

I found that horizon 21.0.0 depends on oslo.i18n>=5.0.1, but oslo.i18n>=5.0.1 requires Python>=3.6, which results in installation failure of horizon in Python 3.5.

Way to fix:
modify setup() in setup.py, add "python_requires" keyword argument:

---
setup(…
     python_requires=">=3.6"
     …)
---
Thanks for your attention.
Best regrads,
PyVCEchecker

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/horizon/+/829629

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/horizon/+/829629
Committed: https://opendev.org/openstack/horizon/commit/ee807825049a75e1dd99f8e7609390800cd4c263
Submitter: "Zuul (22348)"
Branch: master

commit ee807825049a75e1dd99f8e7609390800cd4c263
Author: Akihiro Motoki <email address hidden>
Date: Thu Feb 17 14:33:49 2022 +0900

    Drop py36 and py37 support

    Python runtimes for Zed are 3.8, 3.9 and optionally 3.10 [1][2],
    so tox envs in tox.ini are updated accordingly.

    Declare python_requires >=3.8 in setup.cfg
    python_requires are declared in many projects during dropping
    python 2.7 support. It is good to follow the convention and
    it also clarifies our python interpreter requirement.

    This commit also cleans up python2.7 related stuffs in setup.py.
    Both are related to the supported versions of python,
    so I made both changes in a single commit.

    [1] https://governance.openstack.org/tc/reference/runtimes/zed.html
    [2] https://opendev.org/openstack/openstack-zuul-jobs/src/commit/b740b42fb199d4d695391aaaddf46ca55eab79ac/zuul.d/project-templates.yaml#L542

    Change-Id: I4161816fd1fec19a3834cc7d994b3f761e1ab2ce
    Closes-Bug: #1960887

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/horizon 23.0.0 release.