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

Use in BUILD.bazel files

Once you have set up the dependencies, you are ready to start using them in your BUILD.bazel files. If you haven't done so yet, set it up by following these docs:

To refer to targets in a hub repo pypi, you can do one of two things:

py_library(
    name = "my_lib",
    deps = [
        "@pypi//numpy",
    ],
)

Or use the requirement helper that needs to be loaded from the hub repo itself:

load("@pypi//:requirements.bzl", "requirement")

py_library(
    deps = [
        requirement("numpy")
    ],
)

Note that the usage of the requirement helper is not advised and can be problematic. See the notes below.

Note that the hub repo contains the following targets for each package:

@pypi//numpy - shorthand for @pypi//numpy:numpy. This is an {obj}alias to @pypi//numpy:pkg.
@pypi//numpy:pkg - the {obj}py_library target automatically generated by the repository rules.
@pypi//numpy:data - the {obj}filegroup for all of the extra files that are included as data in the pkg target.
@pypi//numpy:dist_info - the {obj}filegroup for all of the files in the <pkg prefix with version>.distinfo directory.
@pypi//numpy:extracted_whl_files - a {obj}filegroup of all the files extracted from the whl file.
@pypi//numpy:whl - the {obj}filegroup that is the .whl file itself, which includes all transitive dependencies via the {attr}filegroup.data attribute.

:::{versionadded} VERSION_NEXT_FEATURE

The :extracted_whl_files target was added :::

Entry points

If you would like to access entry points, see the py_console_script_binary rule documentation, which can help you create a py_binary target for a particular console script exposed by a package.

‘Extras’ dependencies

Any “extras” specified in the requirements lock file will be automatically added as transitive dependencies of the package. In the example above, you'd just put requirement("useful_dep") or @pypi//useful_dep.

Consuming Wheel Dists Directly

If you need to depend on the wheel dists themselves (for instance, to pass them to some other packaging tool), you can get a handle to them with the whl_requirement macro. For example:

load("@pypi//:requirements.bzl", "whl_requirement")

filegroup(
    name = "whl_files",
    data = [
        # This is equivalent to "@pypi//boto3:whl"
        whl_requirement("boto3"),
    ]
)

Creating a filegroup of files within a whl

The rule {obj}whl_filegroup exists as an easy way to extract the necessary files from a whl file without needing to modify the BUILD.bazel contents of the whl repositories generated via pip_repository. Use it similarly to the filegroup above. See the API docs for more information.

(requirement-helper)=

A note about using the requirement helper

Each extracted wheel repo contains a py_library target representing the wheel‘s contents. There are two ways to access this library. The first uses the requirement() function defined in the central repo’s //:requirements.bzl file. This function maps a pip package name to a label:

load("@my_deps//:requirements.bzl", "requirement")

py_library(
    name = "mylib",
    srcs = ["mylib.py"],
    deps = [
        ":myotherlib",
        requirement("some_pip_dep"),
        requirement("another_pip_dep"),
    ]
)

The reason requirement() exists is to insulate users from changes to the underlying repository and label strings. However, those labels have become directly used, so they aren't able to easily change regardless.

On the other hand, using the requirement() helper has several drawbacks:

It doesn't work with buildifier.
It doesn't work with buildozer.
It adds an extra layer on top of normal mechanisms to refer to targets.
It does not scale well, as each type of target needs a new macro to be loaded and imported.

If you don't want to use requirement(), you can use the library labels directly instead. For pip_parse, the labels are of the following form:

@{name}//{package}

Here name is the name attribute that was passed to pip_parse and package is the pip package name with characters that are illegal in Bazel label names (e.g. -, .) replaced with _. If you need to update name from “old” to “new”, then you can run the following buildozer command:

buildozer 'substitute deps @old//([^/]+) @new//${1}' //...:*