Only install dev-dependencies group package (without prod)

[dvonessen]

Hi,
again thank you for this awesome piece of software.
Now to my question, is it possible to install only a dev-dependencies dependency without installing prod dependencies.

Example use case:

I have two packages A and B.
A has some dependencies but nothing special
B has A as a dependency and other packages.

I want to use both packages in on project (git). A is my infrastructure package and B my pipeline package.
Because A is a dependency of B and there are version constraints, I cannot use B if A is installed in a venv.
Therefore it would be really nice to allow creating e.g. a venv and only install B in it. But keep everything in pdm.lock.

Maybe there is a workaround or a solution out there and I couldn't find it.

Thank you all for your help

[pawamoy]

You can use pdm install --no-default.

[dvonessen]

Thank you for your answer, but I do not quite get it.
Would you please be so kind and give a little bit more information?

[pawamoy]

Sorry, I was answering to "Only install dev-dependencies group package (without prod) ": this is achieved with the --no-default flag, which prevents installing "production" dependencies. I'm not sure to understand the rest of your question.

B has A as a dependency
only install B

So, you want to install only direct dependencies and not transitive ones?

[dvonessen]

Maybe I provide an excerpt from my pyproject.toml and the error which I get:
pyproject.toml:

[project]
name = "cdk-test"
version = "0.1.0"
description = "Default template for PDM package"
authors = [
    {name = "Author", email = "mail"},
]
dependencies = [
    "cdk~=36.2.0",
]
requires-python = "==3.12.*"
readme = "README.md"
license = {text = "MIT"}


[tool.pdm]
distribution = false

[tool.pdm.dev-dependencies]

pipeline = [
    "gcip~=12.5.2",
]

Error while trying to install gcip~=12.5.2 which has a upper constraint on cdk:

> pdm add -dG pipeline "gcip~=12.5.2"
INFO: Adding group pipeline to lockfile
Adding packages to pipeline dev-dependencies: gcip~=12.5.2
🔒 Lock failed
WARNING: Unable to find a resolution for cdk
because of the following conflicts:
  cdk~=30.2 (from [email protected])
  cdk~=30.2 (from [email protected])
  cdk~=30.2 (from [email protected])
  cdk~=30.2 (from [email protected])
  cdk~=30.2 (from [email protected])
  cdk~=36.2.0 (from project)

Removing the constraint is not possible, therefore I want to install gcip into an isolatet venv without installing cdk.

[pawamoy]

Thanks, that's much clearer 🙂

You can try several things:

• Override dependencies, to force specific versions even if they aren't accepted by others: https://pdm-project.org/latest/usage/config/#override-the-resolved-package-versions
• Relax your constraints. If you own gcip, and if possible, relax its constraint on cdk. If possible, relax your own constraint on cdk, which is kinda strict. Maybe relax gcip too (in your dev-deps).

The general advice with Python dependencies is to avoid upper bounds unless you know this will break your code. Python cannot install several different versions of the same package in a given environment (contrary to Javascript for example), so the ecosystem is much more prone to resolution conflicts. Avoiding upper bounds reduces the chance of conflicts.

Same thing for python-requires = "==3.12.*": it's very strict, and should be relaxed, unless you know your code only works on Python 3.12, and not on 3.13 onward, and not on 3.11 downward.

[dvonessen]

Hi,
again thank you for your response. Unfortunately it is not possible to relax the upper bounds at the moment.
I know, that the upper bounds are a bad thing. But at the moment I am not able to solve them.
I will definitely look into the "Override dependencies" topic, but my question was/is, is it possible with pdm to install gcip in a venv without installing cdk? That would solve the hole problem without any changes.

It would be really cool if I could create a venv pdm venv create pipeling and only install gcip in it.

Regards againg