:::{default-domain} bzl :::

Lock

:::{note} Currently rules_python only supports requirements.txt format.

#{gh-issue}2787 tracks pylock.toml support. :::

requirements.txt

pip compile

Generally, when working on a Python project, you‘ll have some dependencies that themselves have other dependencies. You might also specify dependency bounds instead of specific versions. So you’ll need to generate a full list of all transitive dependencies and pinned versions for every dependency.

Typically, you'd have your project dependencies specified in pyproject.toml or requirements.in and generate the full pinned list of dependencies in requirements_lock.txt, which you can manage with {obj}compile_pip_requirements:

load("@rules_python//python:pip.bzl", "compile_pip_requirements")

compile_pip_requirements(
    name = "requirements",
    src = "requirements.in",
    requirements_txt = "requirements_lock.txt",
)

This rule generates two targets:

• bazel run [name].update will regenerate the requirements_txt file
• bazel test [name]_test will test that the requirements_txt file is up to date

Once you generate this fully specified list of requirements, you can install the requirements (bzlmod/WORKSPACE).

:::{warning} If you‘re specifying dependencies in pyproject.toml, make sure to include the [build-system] configuration, with pinned dependencies. compile_pip_requirements will use the build system specified to read your project’s metadata, and you might see non-hermetic behavior if you don't pin the build system.

Not specifying [build-system] at all will result in using a default [build-system] configuration, which uses unpinned versions (ref). :::

pip compile Dependency groups

pip-compile doesn't yet support pyproject.toml dependency groups. Follow pip-tools #2062 to see the status of their support.

In the meantime, support can be emulated by passing multiple files to srcs:

compile_pip_requirements(
    srcs = ["pyproject.toml", "requirements-dev.in"]
    ...
)

uv pip compile (bzlmod only)

We also have experimental setup for the uv pip compile way of generating lock files. This is well tested with the public PyPI index, but you may hit some rough edges with private mirrors.

For more documentation see {obj}lock documentation.