Starting an app from a python script

[aranvir]

Is your feature request related to a problem? Please describe

This might be a bit of a corner case, but I'd like to start and stop my app via a system service. Since I got my app code and its dependencies installed in a virtual environment, I cannot (easily) use the subprocess solution described below. I tried to import the cli.run() function to execute it directly, but due to the click decorators this is not straightforward to use.

Describe the solution you'd like

This would be easy to change, by refactoring it into an regular function and a cli wrapper with the click decorators. So, basically how it's done for uvicorn as well.

Describe alternatives you've considered

What already worked in principle was to start the app as a subprocess with subprocess.run(['wave', 'run', 'app']).
However, that only works from within the environment where wave is installed.

EDIT:
As always, once you ask for help, you find the solution soon after. Using the cli command like h2o_wave.cli.run(["app", "--no-autostart"]) works

Still, I think the refactoring wouldn't hurt :)

[mturoci]

What already worked in principle was to start the app as a subprocess with subprocess.run(['wave', 'run', 'app']).
However, that only works from within the environment where wave is installed.

The trick is to get the path to your current running python executable via sys.executable or manual path, instead of using the global python.

You may specify the path to the wave executable, something like subprocess.run(['venv', 'bin', 'wave', 'run', 'app']) or run it like python -m uvicorn --host 0.0.0.0 --port 8000 app.py:main (also within subprocess) which shall be the equivalent to wave run.

As always, once you ask for help, you find the solution soon after. Using the cli command like h2o_wave.cli.run(["app", "--no-autostart"]) works

Yep, that's a proven fact :). Using cli.run is an option as well, but is kinda hacky so I would advise resorting to one of the options above.

[mturoci]

Adding a few examples of how we do it

wave/e2e/utils.py

Line 38 in db5b17c

self.p = subprocess.Popen([wave_executable, 'run', 'tmp.py', '--no-reload'])

wave/py/examples/tour.py

Line 46 in db5b17c

self.process = subprocess.Popen([

wave/university/h2o_wave_university/cli.py

Line 24 in db5b17c

subprocess.Popen(['wave', 'run', 'h2o_wave_university.university', '--no-reload'], cwd=sys.exec_prefix, env=env).communicate()

[aranvir]

Thanks for the quick response and the examples!

I blanked on the option to use subprocess.run(['venv', 'bin', 'wave', 'run', 'app']). I'm gonna use that from now on :)