python_requires constraint set too strict, 3.6 only.

[hterik]

Apache Airflow version

2.2.1 (latest released)

Operating System

N/A

Versions of Apache Airflow Providers

No response

Deployment

Virtualenv installation

Deployment details

No response

What happened

Trying to install Airflow in a Python 3.7+ project via Poetry gives following error:

The current project's Python requirement (>=3.7) is not compatible with some of the required packages Python requirement:
- apache-airflow requires Python ~=3.6, so it will not be satisfied for Python >=4.0

I am aware poetry is not supported [*] but isn't this constraint on the python version needlessly tight regardless? It comes from setup.cfg: python_requires = ~=3.6

[*] (it normally works after some copying some entries from constraints.txt into Poetry.lock)

What you expected to happen

According to https://airflow.apache.org/docs/apache-airflow/stable/installation/prerequisites.html, "Airflow is tested on 3.6, 3.7, 3.8, 3.9." Installing the pip package in those python environments should work. Preferably in newer versions also as they are generally very compatible.

Can the constraint be set to >=3.6?

How to reproduce

No response

Anything else

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[boring-cyborg]

Thanks for opening your first issue here! Be sure to follow the issue template!

[potiuk]

This statement is absolutely correct: "- apache-airflow requires Python ~=3.6, so it will not be satisfied for Python >=4.0" . Presumably python 4.0 will contain some breaking changes (no-one knows for sure as it is not even planned), yet Python 3.6+ is really supposed to be backwards compatible, so barring some dependencies (that prevent us from 3.10 support) it also supports all 3.6+ versions.

The specification ~3.6 is correctly describing this statement (it means "support any 3.x version above 3.6". I think the message from Poetry is quite wrong. You should silence it, or even better - the project that has >= 3.7 should be corrected, because >= 3.7 is pretty wrong and it SHOULD be changed to ~3.7.

No-one knows what is the scope of the Python 4.0 except tha it will be a breaking release when it comes, so stating that project will work for it is for sure wrong.

[uranusjr]

Poetry's message is technically correct as well, since ~=3.6 (i.e. >=3.6, <4.0) does not cover all of >=3.7, which can be split into >=3.7, <4.0 and >=4.0, and the latter part is not properly covered.

But in any case, this is an issue between Poetry and you as its user. Airflow's specification is correct.

[hterik]

Thank you, i must have misunderstood tilde requirements. Btw do you know if there is a difference in how poetry and pip treat them?
The poetry documentation say that ~1.2 is equivalent to >=1.2.0 <1.3.0, which in the case of ~3.6 case would have implied <3.7.0? Is this an error in their documentation or does it have different behavior?

While https://www.python.org/dev/peps/pep-0440/#compatible-release explains it the way you did.

Changing my own libraries to ~3.7 instead of >=3.7 solved it, even in poetry. 👍 Thanks again.

[uranusjr]

~ is a Poetry-only extension and is different from ~=.

[potiuk]

Yep. Here is the PEP specification of ~= (i.e. compatible release) https://www.python.org/dev/peps/pep-0440/#compatible-release