I am currently struggling with how to run a method from a python file in a virtual environment via crontab.
I have a directory that looks as follows: /home/ubuntu/project has the file file.py
and the folder venv in it. In file.py there is a method() that I want to execute regularly via crontab, using the python and dependencies of the virtual environment.
I have already figured out that I need to use the python from inside the virtual environment, so instead of
python3
I use
/home/ubuntu/project/venv/bin/python3.
Now, I have also found answers to the question how to run a method from the command line, namely via
python3 -c 'import foo; print foo.hello()'.
I have tried to combine the two, but unfortunately
/home/ubuntu/project/venv/bin/python3 -c 'import /home/ubuntu/project/file; print(file.method())'
is invalid syntax. Also
/home/ubuntu/project/venv/bin/python3 -c 'from /home/ubuntu/project/ import file; print(file.method())'
only results in errors. On the other hand,
/home/ubuntu/project/venv/bin/python3 -c 'import file; print(file.method())'
results in file not being found.
How do I do this properly?
Thank you very much for considering this question.
The argument to import is not a file name. The simplest workaround is probably to cd into the directory, then run the script with the virtual environment's Python interpreter.
42 17 * * * cd project && ./venv/bin/python3 -c 'import file; file.method()'
from the crontab of the user whose home directory is /home/ubuntu.
More generally, the directory you want to import from needs to be on your PYTHONPATH,so you could equivalently set that instead of cd into the directory. A third alternative is to make the code in file.py into an installable module, and install it in the virtual environment. For a one-off, this may be an unnecessary chore, but it is definitely the most robust and sustainable solution.