Setting up crontab for my Django Application

Question

I had an issue with setting up crontab for my Django application for a week and I have almost figured out the same. (Issue linked with Unable to make a function call using Django-cron)

My crontab -e syntax is

* * * * * /Users/ashwin/dashboard/proj_application/exec.sh >> /Users/ashwin/dashboard/proj_application/data.log 2>&1

And in my exec.sh, I have

#!/bin/bash
cd "$(dirname "$0")";
CWD="$(pwd)"
echo $CWD
python -c 'import proj_application.cron as cron; cron.test()'

And in cron.py,

from django.core.mail import send_mail
from smtplib import SMTP
from email.mime.text import MIMEText
import datetime

def test():
    message = "<p>This is test mail scheduled to send every minute</p>"
    my_email = MIMEText(message, "html")
    my_email["From"] = "[email protected]"
    my_email["To"] = "[email protected]"
    my_email["Subject"] = "Title"

    sender = "[email protected]"
    receivers = ["[email protected]"]

    with SMTP("localhost") as smtp:
        smtp.login(sender, "yyy@1234")
        smtp.sendmail(sender, receivers, my_email.as_string())

Actual Problem:

The crontab is now able to call the exec.sh file and I am able to print $CWD in echo, when the call comes to cron.py, It is unable to recognize django.core.mail and throws the following error.

from django.core.mail import send_mail
ImportError: No module named django.core.mail

I think, I need to set up virtual environment or python variable path somewhere, but since I am new to crontab, I am not sure how to do that.

Any assistance is appreciated. Thanks in advance.

Answer 1

The way I interpret this is that you are normally running your script in a virutal environment, and it is failing now that you added it to a cron job. If this is incorrect, just skip to the last paragraph.

To run a cron job through a virutal environment, you need to use the virtual environment's python as the python you want. E.g to run the cron.py file:

* * * * * /path/to/venv/bin/python3 /path/to/cron.py >> /Users/ashwin/dashboard/proj_application/data.log 2>&1

This is the way I would recommend doing it, as it doesn't seem like that shell script is entirely necessary (anything in there can easily be done at the top of the python script), but if it is you can do something similar where you call the virtual environment's python instead of the default python. like this:

/path/to/venv/bin/python3 -c 'import proj_application.cron as cron; cron.test()' 

However, if this doesn't work, this may not be an issue with the cron job, and instead with the django setup of the mail client (e.g. making sure it is included in the installed apps, etc.)

Since it is a little unclear where your issue is (mail client setup, cron setup, venv configuration, etc), if you are sure it is an issue with running your scripts you usually run in a virtual environment, than these steps should help, otherwise I would make sure your mail client is configured correctly. Make sure your scripts are correct by running them in the console (not through a cron job), and then you can come back and update the post with more detailed info about where the problem you have lies.

Answer 2

yes you are correct you may need to use virtual environment(although its optional but best practice).

To create virtual environment(expects python to be installed prior)

python -m venv venv

To activate (path may differ based on OS(mine is windows))

source venv/Scripts/activate

To install dependency in virtual environment

pip install Django

Now you all set to use virtual env's Django.

which python should map to venv path.

Now you have two ways to run python script #1 use direct python path

absolute/path/of/venv/bin/python3 -c 'import proj_application.cron as cron; cron.test()'

#2 activate virtual environment and use the bash script as same.

#!/bin/bash
cd "$(dirname "$0")";
CWD="$(pwd)"
echo $CWD
source venv/Scripts/python   # this will be in windows
python -c 'import proj_application.cron as cron; cron.test()'