The project structure is

📁 pants-tests/
├─📄 .gitignore
├─📁 lib/
│ └─📁 my-pkg/
│   ├─📄 pyproject.toml
│   └─📁 mypkg/
│     ├─📄 __init__.py
│     ├─📄 something.py
│     └─📄 BUILD
└─📄 pants.toml

And the

pyproject.toml

defines "numba" as dependency

[project]
name = "my-pkg"
requires-python = ">=3.10"
description = "A package"
version = "0.1.0"
dependencies = ["numba"]

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"


[tool.setuptools.packages.find]
where = ["."]
include = ["mypkg*"]

The

lib/my-pkg/mypkg/something.py

imports numba (and matplotlib):

import matplotlib
import numba


def foo():
    print(matplotlib)
    print(numba)


if __name__ == "__main__":
    print("Hello from ", __file__)

and I'm using pants 2.15.0

When running

pants tailor ::

it creates

lib/my-pkg/mypkg/BUILD

with following contents:

python_sources()

That is the only

BUILD

file created.

When trying to check the dependencies, I see nothing

niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
14:13:43.36 [WARN] Pants cannot infer owners for the following imports in the target lib/my-pkg/mypkg/something.py:

  * matplotlib (line: 1)
  * numba (line: 2)

If you do not expect an import to be inferrable, add `# pants: no-infer-dep` to the import line. Otherwise, see <https://www.pantsbuild.org/v2.15/docs/troubleshooting#import-errors-and-missing-dependencies> for common problems.
niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies --transitive lib/my-pkg/mypkg/something.py 
niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
niko@niko-ubuntu:~/tmp/pants-tests$

Should the

BUILD

have some (other) content? I would expect that "numba" is added automatically as 3rd party dependency as it is listed in

pyproject.toml

. That seems not be the case. Is there a way to get the dependencies listed automatically? If not, where I should put manually put them?

Reading from the pants tailor docs it says:

Auto-generate BUILD file targets for new source files.

from which I would assume the 3rd party dependencies are added to the BUILD files automatically by

pants tailor ::

. Why I don't see it? It does not specifically say if it reads the dependencies from setup.py or pyproject.toml or requirements.txt, or directly from import statements from the source files.. 🤔

Ah, maybe it doesn’t even support that style of file at all. Can you bump back up to 2.16?

On pants 2.16.0 the results are quite much identical. The only

BUILD

file created by

pants tailor ::

has same contents and here is what the dependency check looks like

niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
14:31:59.42 [WARN] DEPRECATED: the factory default interpreter constraints value is scheduled to be removed in version 2.17.0.dev0.

You're relying on the default interpreter constraints that ship with Pants (('CPython>=3.7,<4',)). This default is deprecated, in favor of explicitly specifying the interpreter versions your code is actually intended to run against.

You specify interpreter constraints using the `interpreter_constraints` option in the `[python]` section of pants.toml. We recommend constraining to a single interpreter minor version if you can, e.g., `interpreter_constraints = ['==3.11.*']`, or at least a small number of interpreter minor versions, e.g., `interpreter_constraints = ['>=3.10,<3.12']`. See <https://www.pantsbuild.org/v2.16/docs/python-interpreter-compatibility> for details.

Set explicit interpreter constraints now to get rid of this warning.
14:32:07.38 [WARN] Pants cannot infer owners for the following imports in the target lib/my-pkg/mypkg/something.py:

  * matplotlib (line: 1)
  * numba (line: 2)

If you do not expect an import to be inferrable, add `# pants: no-infer-dep` to the import line. Otherwise, see <https://www.pantsbuild.org/v2.16/docs/troubleshooting#import-errors-and-missing-dependencies> for common problems.
niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
niko@niko-ubuntu:~/tmp/pants-tests$

Thanks @broad-processor-92400, I changed to 2.16.0 and added manually a

BUILD

file next to the

pyproject.toml

:

📁 pants-tests/
├─📄 .gitignore
├─📁 lib/
│ └─📁 my-pkg/
│   ├─📄 pyproject.toml
│   ├─📄 BUILD    <----- manually added
│   └─📁 mypkg/
│     ├─📄 __init__.py
│     ├─📄 something.py
│     └─📄 BUILD   <---- from pants tailor (automatic)
└─📄 pants.toml

The

lib/my-pkg/BUILD

has only this as content:

python_requirements(source="pyproject.toml")

Now the dependencies are shown correctly:

niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
14:35:12.88 [WARN] Pants cannot infer owners for the following imports in the target lib/my-pkg/mypkg/something.py:

  * matplotlib (line: 1)

If you do not expect an import to be inferrable, add `# pants: no-infer-dep` to the import line. Otherwise, see <https://www.pantsbuild.org/v2.16/docs/troubleshooting#import-errors-and-missing-dependencies> for common problems.
lib/my-pkg#numba

The

matplotlib

I purposefully did not add, so I could see what

pants

does automatically. On second run it looks like this:

niko@niko-ubuntu:~/tmp/pants-tests$ pants dependencies lib/my-pkg/mypkg/something.py 
lib/my-pkg#numba

thanks a lot for the help!