My monorepo directory structure looks like this:

src
|- common
|  |- packageA
|     |- BUILD
|     |- __init__.py
|     |- packageA_class.py
|     |- ...
|  |- packageB
|     |- packageB
|        |- BUILD
|        |- __init__.py
|        |- packageB_class.py
|        |- ...
|     |- setup.py
|     |- BUILD
|     |- ...

In this case,

packageB

is coming from another repo. In a non-monorepo world, I would simply

pip install packageB

, and use

import packageB

in packageA's code. However, once I moved it to my monorepo, I can't get the dependency coded correctly in

packageA

. Here's my `src/common/packageB/BUILD`:

python_sources()

python_distribution(
    name="packageB_dist",
    provides=setup_py(
        setup_script="setup.py",
        name="packageB",
        version="0.2.0",
    ),
)

And `src/common/packageA/BUILD`:

python_sources()

pex_binary(
    name="packageA_bin",
    entry_point="packageA_class.py",
    dependencies=["src/common/packageB:packageB_dist"]
)

My expectation here is that when I try to build

packageA

, it will use `packageB`'s

setup.py

to install it, and then I can do a simple

import common.packageB

, but that gives me a

ModuleNotFoundError

. What am I missing here to get this use case working? Running

./pants dependencies src/common/packageA

correctly indicates the problem:

13:23:53.21 [WARN] Pants cannot infer owners for the following imports in the target src/common/packageA/packageA_class.py:

  * common.packageB (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/v2.14/docs/troubleshooting#import-errors-and-missing-dependencies> for common problems.
src/common/packageA/packageA_class.py
src/common/packageB:packageB_dist

So it sees the packageB distribution, but cannot resolve its import.

All that said, Pants does support building “local dists” and consuming them. Try moving that dependency on

src/common/packageB:packageB_dist

to A’s

python_sources

target. It’s the code in that target that is actually consuming packageB via an import.

The thing I’m not sure about is that Pants should be able to infer a source-level dep because of that

common.packageB

import, so not clear why that is failing.

Oh, what does

./pants roots

show?

So that explains why dep inference fails

Without invoking the setup.py

(and remove the setup.py if you move things up a level)

Or you can add

src/common/packageB

as a source root

The alternative, if you do want to stick with running the

setup.py

is to add

src/common/packageB

as a source root

But note that then the import will be

import packageB

, not

import common.packageB

but presumably

import packageB

was how packageA was importing it before the monorepo?

Thanks for your help!