How to launch submodules from a python package?

Question

I am working on a robotics project with my lab. (Github) Most of the main components are done and documented. The setup is as follows:

• We run opstn on the base station. It has a server used to communicate controller position to the robot.
• We run rpi on a raspberry pi running on the robot. The two communicate via wifi and have a static address. The raspberry pi has a client program which requests the controller positions when it has time, decides what to run the motor.
• The raspberry pi communicates with an mbed via USB to allow for hardware PWM.
• The raspberry pi will also be working with I2C devices for monitoring data, and communicating it back to the base station for processing. This will eventually be run as a separate server process, and the base station will have a client process communicating with it.
• The base station might need to have a client module to interpret the device data, running as a separate process.

The code does work, but we have to run it in a somewhat longwinded way:

• On the base station, cd into kaginawa and python -m opstn, running opstn/__main__.py
• SSH into the raspberry pi, cd into kaginawa and python -m rpi, running rpi/__main__.py

I was wondering how to properly launch submodules. For the rpi/__main__.py, I was thinking of providing two functions (the motor-controlling client and the device server) in __main__.py, and use multiprocessing to run them. Experiments seem to indicate that this would work.

What I want to do, though, is zip my directory into an executable, and then simply ./start_robot. This is what the Makefile does, and it works well. However, whatever I try, I seem to be unable to start opstn at all. And I will also need to work with the SSH too, since I will need to launch rpi with sudo. I can probably do that with paramiko using this reply.

If it is possible, I am thinking of using os.uname()[1] to check if it is on the raspberry pi and launch rpi, and opstn otherwise.

tl;dr How do you launch submodules that contain a __main__.py from the root __main__.py of a python package?

Answer 1

The toplevel directory in the project should not be a Python package. It could be a directory with setup.py instead.

You shouldn't cd inside Python package. Put your zip somewhere in PYTHONPATH (check by print(sys.path)) and use absolute names to run submodules e.g., run:

$ python -m kaginawa.opstn

to run kaginawa/opstn/__main__.py script or run:

$ python -m kaginawa.rpi

to run kaginawa/rpi/__main__.py.

If you want to choose what to run at runtime then you could call kaginawa.opstn.main() or kaginawa.rpi.main() functions in kaginawa/__main__.py. And run it:

$ python -mkaginawa

You could run the zip directly.

To simplify including dependencies, you could use PyInstaller, cx_Freeze to bundle your code.