Just getting started - I setup a small example repo to capture what I think I want to do, but where I'm running into questions - https://github.com/rjrudin/pants-monorepo . Hoping someone can help with the initial 4 questions I have in the README file, which - high-level - are: 1) Why are dependencies not shown; 2) Recommendation for running tests in PyCharm; 3) Controlling version of Pytest; 4) How to do what I used to do via Gradle with app/lib dependencies .

You can check pants documentation for how to set pytest version https://www.pantsbuild.org/docs/python-test-goal#pytest-version-and-plugins

Dang, @refined-addition-53644 beat me to it 😂

Re: Pytest version - it dovetails with question 2 - what's the recommended way for PyCharm to run a test? Currently, we add pytest to a requirements_test.txt file and that gets dumped into the venv via "pip install". If I configure the pytest block in pants.toml, that doesn't make any difference to PyCharm.

I am not a PyCharm user. So can't say much but if it's similar to VS code, I think using a virtual env would be the way to go as suggested here https://www.pantsbuild.org/docs/contributor-setup#hooking-up-the-python-virtual-environment

Right now, when you use Pants you're kind of giving the keys over to Pants to run things (including test). Currently, if you want to wire your editor to understand your env, you'll have to do that yourself. Pants does provide some info on how to help though: https://www.pantsbuild.org/docs/setting-up-an-ide

I waited long enough 😄

I'm hopeful 2022 will bring Pants-supported in-editor plugin support

Multiple Python lockfiles is coming soon!

@happy-kitchen-89482 Now do VSCode 😂 I'm an open-source fanboy

Initially for JVM, but we want to provide Python support soon as well

Thanks - getting back to question 1 - if I understand https://www.pantsbuild.org/docs/python-third-party-dependencies correctly, I should still have a single requirements.txt file (which is true of this example that I found to be helpful, in addition to the pants example - https://github.com/semaphoreci-demos/semaphore-demo-python-pants ). But when I run a goal, pants will figure out which dependencies are really needed, correct? (If so, that sounds good, just wrapping my head around because it's different from the Java/Gradle approach of each subproject having its own list of dependencies, and subproject A can depend on B and so forth)

Well, the plan is to provide the support via LSP/BSP, which I think will make it easier to integrate with VSCode too?

@happy-kitchen-89482 sounds right

@lively-exabyte-12840 Yes, that is correct

Got it - related to that, we're not creating a pex binary yet, but I assume if we did, Pants will compute the subset of dependencies to be included in that binary? (I am equating "pex binary" with "executable jar", where again, Java/Gradle would look at the dependencies of each subproject to compute what should get stuffed into that jar)

Correct

Thanks, I'll keep progressing further (main thing is I need to get to a "this works, we can migrate over" point and also be able to answer questions for my team)

Similarly if you use Pants to build an AWS Lambda or a GCP Cloud Function, it'll contain just what it needs

I think the ultimate goal is - when we deploy, we of course only want the dependencies that are needed (regardless of the build tool). Having a single requirements file and then trusting Pants to only use the necessary dependencies is a good approach, though I think we'll need to build up that trust on the team via evidence. This is my lack of Python knowledge, but I'm thinking right now in Java terms of being able to scan the classpath at runtime to verify what's been loaded and what hasn't been loaded

Running

./pants dependencies <file>

should delight you then 😉

Yes, you can always run

./pants dependencies

,

./pants dependees

and

./pants peek

to verify that dependencies are what you expect

13393 is good stuff; that's one concern I've been thinking about, where someone coding in app1 could easily grab code from app2, which we wouldn't want

you can always run ./pants dependencies, ./pants dependees and ./pants peek to verify that dependencies are what you expect

See https://www.pantsbuild.org/docs/project-introspection