How to set different dependencies based on os version?

[gzm55]

Like [target.linux-64.dependencies] table, can we set different dependencies based on the detected virtual package versions? for example set special version for linux = "2.6.32"

[ruben-arts]

I've been brainstorming about this as well, in my case for __cuda but the same issue holds.

If we build a [target.cfg('linux=2.6.32').dependencies], what needs to happen in the solver is that we build a complete new environment. So in terms of solving and required system resources this might not really help.

The power would be auto selecting a certain environment for the specialized target. So pixi shouln't just use the available default env with the current platform but have a get_best_target(current_platform, available_virtual_packages) function to figure out the most specialized environment.

[gzm55]

The power would be auto selecting a certain environment for the specialized target.

Can we auto enable some features based on the virtual packages? We can put this kind of features into all envs including default. Also a flag is needed to exclude those features.

[ruben-arts]

The features are locked in environments but we could think of a better way to decide which is the "default" environment for your platform. e.g.:

[environments]
cuda = { features = ["cuda12"], default-if = { cuda = "12.2" } }
cuda_old = { features = ["cuda11"], default-if = { cuda = "11" } }

Note

This is just a brain dump, not a design proposal.

[gzm55]

what if both default-if clauses are evaluated to true for two environments? one is cuda = 12.2, another is glibc = 2.12

[ruben-arts]

We have this interactive ambiguity message, that we could reuse:

pixi/examples/multi-machine
➜ pixi run train 
? The task 'train' can be run in multiple environments.

Please select an environment to run the task in: ›
❯ default
  cuda

[gzm55]

then we could probably have to make a matrix of envs for virtual packages.

it's better to let the conditional check in a more composable level. if feature is not suitable, how about a if field for each dependency?

[dependencies]
pytorch-cpu = { version = "~=1.1", channel = "pytorch", if: { cuda: "...", linux: "..." } }