Recommendations for caching poetry dependencies causes the wrong python version to be used for poetry install about setup-python

[evilhamsterman]

It's always struck me as a bad chicken/egg problem that poetry is the only cache type that requires the environment manager to be installed before it can be used. Even pipenv is not required to be installed

setup-python/src/cache-distributions/pipenv-cache.ts

Line 20 in 82c7e63

// because pipenv is not preinstalled on hosted images and virtualenv is not created:

it just uses the default pipenv location.

The Poetry default cache location is well known and I bet in CI the vase majority of projects are using that case. The big difference appears to be that the Poetry option is trying to support the fact that Poetry can install virtual environments in the project. Pipenv can also do this but it's just ignored for that option. I'd recommend just caching the default location like Pipenv, or you could have an option for enabling caching in project virtual environments it people use it.

[HarithaVattikuti]

Hello @sdb9696
Thank you for creating this issue. We will investigate it and get back to you as soon as we have some feedback.

[andwaredev]

Hello @sdb9696 – my team ran into this same issue recently. We solved it by pinning the python version in our pyproject.toml file, under [tool.poetry.dependencies]. See example below.

[tool.poetry.dependencies]
python = "3.11.4"

[sdb9696]

Thanks @andwaredev but we run our CI against all supported python versions to check there are no issues so not sure this workaround will help.

[silverwind]

I find it highly concerning that the recommend and only working solution for caching poetry venvs is to install poetry before setup-python. It can not be assumed that python is present before setup-python has run because some runner images will not have python pre-installed.

This is what I would like to see working:

- uses: actions/setup-python@v5
  with:
    python-version: '3.12'
    cache: 'poetry'
- run: pipx install poetry

[evilhamsterman]

@silverwind You can tell poetry to use a specific version of python prior to running install poetry env use <python executable> then run poetry install

https://python-poetry.org/docs/managing-environments#switching-between-environments

[silverwind]

@evilhamsterman doesn't really help me if there is simply no python installed before setup-python ran. Of course one could do workarounds by running setup-python twice, but I rather skip on enabling cache than doing such hacks.

[adminy]

I find it highly concerning that the recommend and only working solution for caching poetry venvs is to install poetry before setup-python. It can not be assumed that python is present before setup-python has run because some runner images will not have python pre-installed.

This is what I would like to see working:

- uses: actions/setup-python@v5
  with:
    python-version: '3.12'
    cache: 'poetry'
- run: pipx install poetry

This also makes the assumtion that you have pipx which I do not :)

I'd highly recommend to install poetry as part of this python version fetching if cache is set to poetry.

Chances are everyone is going to need poetry if they are using poetry cache, so maybe get the specific python version with poetry pre-installed. This seems to be the only viable solution.

[silverwind]

This also makes the assumtion that you have pipx which I do not :)

I think setup-python does install pip and its variants currently, right?

[silverwind]

This also makes the assumtion that you have pipx which I do not :)

I think setup-python does install pip and its variants currently, right?

Apparently, it doesn't so to install poetry without pip and having a poetry cache, this would be the ideal:

- uses: actions/setup-python@v5
  with:
    python-version: '3.12'
    cache: 'poetry'
- uses: snok/install-poetry@v1