Hi all 👋! I'm new to Pants but excited to see what it can do for migrating a multi-repo set up I have into a monorep. I'm hitting a

No module named main

error -- which I can see is due to having two projects with a

src/main.py

. Indicative project structure here:

├── BUILD
├── apple-pie-api
│   ├── BUILD
│   ├── Pipfile
│   ├── Pipfile.lock
│   ├── requirements.txt
│   └── src
│       ├── main.py
│           ...
├── common-requirements.txt
├── pants
├── pants.toml
└── randmoji-api
│   ├── BUILD
│   ├── Pipfile
│   ├── Pipfile.lock
│   ├── requirements.txt
│   └── src
│       ├── main.py
│           ...
├   ...

I hit the issue when I try to execute the output pex for one of the projects; e.g., via

./pants package apple-pie-api:pex_binary && ./dist/apple-pie-api/pex_binary.pex

. Renaming one of the

main.py

(e.g., to

main2.py

) does the trick. But I'm wondering if there's a way to avoid needing to do that? Looking at the source roots https://www.pantsbuild.org/docs/source-roots this isn't in those example set ups, so perhaps I'm off piste here? But this is a set up I'd like to use as part of a transition to pants.

Thanks for the repo. If you run the following you get a clue:

$ ./pants package apple-pie-api:pex_binary
15:10:05.90 [WARN] The pex_binary target apple-pie-api:pex_binary has the field `entry_point='src/main.py'`, which maps to the Python module `main`, but Pants cannot safely infer a dependency because >1 target exports this module, so it is ambiguous which to use: ['apple-pie-api/src/main.py:../apple-pie-api', 'randmoji-api/src/main.py:../randmoji-api'].

Please explicitly include the dependency you want in the `dependencies` field of apple-pie-api:pex_binary, or ignore the ones you do not want by prefixing with `!` or `!!` so that <=1 targets are left.

Alternatively, you can remove the ambiguity by deleting/changing some of the targets so that only 1 target exports this module. Refer to <https://www.pantsbuild.org/v2.4/docs/troubleshooting#import-errors-and-missing-dependencies>.
15:10:05.91 [INFO] Wrote dist/apple-pie-api/pex_binary.pex

Which is followed via:

$ git diff
diff --git a/apple-pie-api/BUILD b/apple-pie-api/BUILD
index 3f3f778..44e6ed6 100644
--- a/apple-pie-api/BUILD
+++ b/apple-pie-api/BUILD
@@ -7,6 +7,9 @@ python_library(
 pex_binary(
     name="pex_binary",
     entry_point="src/main.py",
+    dependencies=[
+        "apple-pie-api",
+    ]
 )
 
 # You need `python_requirements` to teach pants that this project has third-party requirements

Which nets you:

$ ./pants package apple-pie-api:pex_binary
15:10:00.12 [INFO] Wrote dist/apple-pie-api/pex_binary.pex
$ zipinfo dist/apple-pie-api/pex_binary.pex | tail -10
-rw-r--r--  2.0 unx      558 b- defN 80-Jan-01 00:00 .bootstrap/pex/vendor/_vendored/setuptools/pkg_resources/py31compat.py
-rw-r--r--  2.0 unx      984 b- defN 80-Jan-01 00:00 .bootstrap/pex/venv_bin_path.py
-rw-r--r--  2.0 unx      155 b- defN 80-Jan-01 00:00 .bootstrap/pex/version.py
-rw-r--r--  2.0 unx      590 b- defN 80-Jan-01 00:00 PEX-INFO
-rw-r--r--  2.0 unx     2868 b- defN 80-Jan-01 00:00 __main__.py
-rw-r--r--  2.0 unx      932 b- defN 80-Jan-01 00:00 main.py
drwxr-xr-x  2.0 unx        0 b- stor 80-Jan-01 00:00 numerics/
-rw-r--r--  2.0 unx       55 b- defN 80-Jan-01 00:00 numerics/__init__.py
-rw-r--r--  2.0 unx      658 b- defN 80-Jan-01 00:00 numerics/pi.py

And the desired outcome:

$ ./dist/apple-pie-api/pex_binary.pex 
Traceback (most recent call last):
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 489, in execute
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 406, in _wrap_coverage
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 437, in _wrap_profiling
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 545, in _execute
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 672, in execute_entry
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/.bootstrap/pex/pex.py", line 684, in execute_module
  File "/usr/lib/python3.8/runpy.py", line 210, in run_module
    return _run_code(code, {}, init_globals, run_name, mod_spec)
  File "/usr/lib/python3.8/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/home/jsirois/dev/mattjw/jsirois-pants-multiproject-mwe/dist/apple-pie-api/pex_binary.pex/main.py", line 6, in <module>
ModuleNotFoundError: No module named 'uvicorn'

Well - not quite the desired outcome, but now you're on the road to working more things out.

Thanks @enough-analyst-54434! Just digesting now!