It's not possible to generate any files outside of the sandbox, is it? I was hoping to have a task that creates and populates a

venv

but I think that can't be done from within Pants, right?

Atm, Pants can only itself write to the build root, meaning where your repo is. `Workspace.write_digest()`: https://www.pantsbuild.org/docs/rules-api-file-system#workspacewrite_digest A subprocess can also write wherever it wants - Pants doesn't sandbox that

I love Pex but didn't know about that feature. That's super cool.

Something like this script? https://www.pantsbuild.org/docs/python-third-party-dependencies#tip-set-up-a-virtual-environment-optional

yeah, exactly. Just thought it'd be more user friendly to be able to do something like

pants venv

or

pants requirements

Just thought it'd be more user friendly to be able to do something like pants venv

Strong agreement. We're starting work soon to support multiple constraints files in a repo, and part of that will involve Pants generating constraints files for you. Possibly creating the venv too for the sake of IDEs. That bash script is not where we want to end up

makes sense. But I gather I can't have a Pants rule write outside the sandbox so I couldn't build this myself?

You can have it write to the build root, e.g. to the

dist/

folder, which is what

./pants package

does If you want to write outside the build root, atm you would need a subprocess to do that via

Process

. (Probably not relevant to you, but note that doing that would not be safe with Remote Execution - if the remote worker wrote to some global directory via a

Process

, it would mutate the remote worker, but not your local machine)

got it. Thanks again for all your help!

You need the

python_library

to teach Pants your code exists. Then, if you set up your

entry_point

for the

pex_binary

to be in the format

main.py

, Pants can use dependency inference to figure out which code you're using

pex_binary

does not have any

sources

, it can only depend on other targets

Got it. Thanks.

If you haven't yet, it can be helpful to run

./pants tailor

(in a clean git state) https://www.pantsbuild.org/docs/create-initial-build-files

yeah - that's how I figured out the

python_library

was needed.