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On Tue, May 12, 2020, at 7:44 AM, Sorin Sbarnea wrote:
> I recently discovered that this problem goes even deeper, please read 
> all comments on https://github.com/tox-dev/tox/issues/1565
> 
> Due to this it seems to be impossible to define zuul jobs that use a 
> specific python version regardless the environment name. If you want to 
> force "linters" job to use python3.8 only under CI/CD, is impossible.
> 
> Using basepython=pythonX.Y combined with 
> ignore_basepython_conflict=False seems the only way to enforce version 
> use, and it comes at the cost of not being flexible for developers (as 
> they may not have the exact version that we want to use on CI jobs).
> 
> While for unittest jobs we do use pyXY in the environment name, we do 
> not have the same for "linters", "docs". Alternative to add 
> `{pyXY}-linters` seems to be the only option to trick it.

I don't think that is a trick, this is an intentional feature of tox to solve the problem you have. If you want a specific version of python to be used tox aims to help you do that via the pyXY* environments. https://tox.readthedocs.io/en/latest/config.html#tox-environments clearly describes this behavior.

> 
> Another (dangerous) approach would be to assure that the only python 
> version available on each nodeset used by tox job is the one we want to 
> use for testing.
> 
> I engaged with Bernat Gabor (tox maintainer) on Gitter/tox-dev about 
> this issue and apparently there is no solution. Tox v4 has some changes 
> planned but is far away.
> 
> 
> * --discover cannot be used to enforce python detection
> * tox own interpreter version cannot be used to enforce version being 
> picked (at least this is what the maintainer told me)
> 
> Sadly, after spending a good number of hours on that I am more confused 
> that I was when I started.
> 
> With Zuul nodepool images that can change over night on multiple zuul 
> servers (at least 4 i use), it seems that tox-* jobs are joing to be a 
> permanent source of surprises, where we can discover that what they say 
> they test is not really what they did.

In the case of linting, without a specific python version set, they are doing what you asked: run the linters without a specific version of python and use what is available. The problem I described earlier was asking for a specific python version and not getting that version. Running tox -e linters does not ask for a specific version.

The workaround you described above is the actual tox solution to this problem. You should run py38-linters if that is your intent.

> 
> Anyone missing a `make foo` command? ;)
> 
> Cheers
> Sorin