Constraint support for `uv lock` (as `uv pip install -r requirements.txt --constraint constraints.txt`)

[mthiboust]

Is there an equivalent of uv pip install -r requirements.txt --constraint constraints.txt for uv lock/uv sync?

Use case:

I want to install my python project inside a docker image whose base image (jupyter/base-notebook with dependencies installed via mamba in this case) has already installed some python libraries. I would like to avoid version conflicts by giving previously installed lib versions as constraints to lock my project dependencies (exporting previously installed libs with pip list --format freeze to create the constraints.txt file).

Is it possible or do you see a workaround?

[charliermarsh]

You can provide constraints in the pyproject.toml like:

[tool.uv]
constraint-dependencies = ["flask==3.0.0"]

But we don't currently have a way for you to provide a list of constraints like that. A few people have asked about it though, we should probably figure out a realistic workflow for it.

[zanieb]

I think we can track this in https://github.com/astral-sh/uv/issues/6518

I feel relatively strongly that constraints should be defined in the project metadata instead of provided directly to uv lock.

[mthiboust]

Thanks for your answers and linking this to the other issue.

Indeed, the following workflow using uv add would be great:

• Retrieving already installed packages with their version: pip list --format freeze > constraints.txt
• Adding those as constraint dependencies to project metadata: uv add --constraint constraints.txt
• Locking the project: uv lock