#21194 Resolves should automatically include transitive targets, and not restrict 1st party source code Issue created by jasondamour Problem Migrating a monorepo with libraries and services with conflicting version constraints to pants requires so much effort compared to the intuitive pattern in poetry/pip. For example, imagine the following repository: flowchart LR X(3rd-party-lib) subgraph Libraries/ libA libB end subgraph Services/ service1 service2 end libA -.-> libB libB -.->|>=1| X service1 --> libA service2 --> libB service2 -.->|==2| X Loading Sample repo: https://github.com/jasondamour/pants-vs-poetry This repository is valid in poetry. We can run

poetry lock

for each service: • `service1`: has all dependencies from

libA

,

libB

, and

3rd-party-lib==3.0

(latest version of 3rd-party-lib) • `service2`: has all dependencies from

libB

and

3rd-party-lib==2.0

All the same concepts should apply to pythonrequirements from requirements.txt and pep-621 compliant pyproject.toml files, I'm just using poetry as an example For the equivalent in Pants, I need to: 1. In pants.toml, define a resolve per service and library 2. Parametrize targets to add ALL libraries to ALL resolves a. Pants struggles to infer dependencies when resolves are enabled, so it also requires a lot of manual dependencies Solution Resolves should (optionally) behave more like poetry per-module Virtual Environments. • A "resolve" should just represent version constraints for 3rd party dependencies (including transitive) • Don't impose restrictions on what 1st party code can run with a resolve • Don't require a lockfile for every resolve For example: 1. Define resolves: # pants.toml [python.resolves] service1 = "Services/service1/pants.lock" service2 = "Services/service2/pants.lock" 1. Set

Services/service1/BUILD: poetry_requirements(resolve="service1")

to add direct targets of this directory to

@resolve=service1

(and repeat for service2) 2. Declare a dependency (same as vanilla poetry)

services/service1/pyproject.toml: libA = {path = "../../Libraries/libA", develop = true}

3.

pants generate-lockfile --resolve=service1

should create a lockfile which pins

libA

,

libB

, and

3rd-party-lib

4.

pants test Libraries/libA::

should run without a resolve or lockfile Describe alternatives you've considered We may just go back to directly using poetry for all dependencies, and exporting lockfiles for services from poetry for pants to consume in tests. I think that will give us exactly what I'm describing. pantsbuild/pants