Support multi envs

[zen-xu]

Problem description

I need multiple Python version environments, but I can't declare multiple versions simultaneously.

Maybe we can specify envs like

# pixi.toml

[env.py37.dependencies]
python = "3.7.*"
default = true

[env.py311.dependencies]
python = "3.11.*"

After exec pixi install will create two env dirs

• .pixi/py37
• .pixi/py311

Control the environment through the -e/--env option

pixi run -e py311 python

[baszalmstra]

This is related to #239 .

Although we are not entirely sure what it will look like we are very keen to have something like this implemented in pixi.

[baszalmstra]

See #239 (comment) for some more thoughts

[zen-xu]

It seems issue #239 can't solve my problem. I need to have multiple environments locally so I can test in different Python versions.

[baszalmstra]

I think testing in different Python versions is also the use case mentioned in #239 .

There are a couple of different use cases for having multiple environments but none of them are super trivial to implement because we still want to lock all the environments down to ensure reproducibility on anyone's machine.

We are still in the design phase for this issue but I'm sure we'll come up with something. :)

[pavelzw]

This proposal is relevant to this issue: https://gist.github.com/0xbe7a/bbf8a323409be466fe1ad77aa6dd5428

[ruben-arts]

https://github.com/bokeh/bokeh/tree/branch-3.4/conda Good example of what we need to solve with pixi multi envs.

[ruben-arts]

Started a project that implements this issue: https://github.com/orgs/prefix-dev/projects/10

[ruben-arts]

Update

Done:

• The de-serialization of the environments and feature are pretty much done. (
• In the code there are Environment and Feature objects which can be used to fetch the important specified information.
• All the sorting and overwriting is implemented as stated in the proposal.

Next:

• We still need make the logic to select a specific environment instead of using the default.
• We need to modify the CLI to allow the user to specify an environment.

We expect to have a first working multi environment project end of next week 🚀 . If there are any users that want to poke/stress the logic in the tests to find bug. Please do so, help is much appriciated ❤️ !

[pavelzw]

This can be closed now or is anything still missing?

[ruben-arts]

The last parts we want to build in the short future are defined in this project: https://github.com/orgs/prefix-dev/projects/10?query=is%3Aopen+sort%3Aupdated-desc

Should be one more sprint.

[dhirschfeld]

https://prefix.dev/blog/introducing_multi_env_pixi

/close