crontab | A crontab entry parser | Cron Utils library

This seems like a problem with the dependency that I'm using (UnixDateTimeField) as the error thrown out was pointed toward the package in my virtual environment.

I resorted to store the time in an integer field:

I think you could just set up a bash script that executes your PHP, which would have no for loop as in your code, but simply be the echo:

If the Python file only need python (not other library)

On modern Docker I'd never use this pattern, and in particular I'd avoid volumes_from:.

volumes_from: has the two problems of not being clear of what exactly it's mounting and not having any control over where it gets mounted. If the image for your backup had a VOLUME declaration in its Dockerfile, for example, that volume would get mounted in your cron container at the exact same path as in the backup container, even though it's not listed in this docker-compose.yml anywhere. That can lead to surprising outcomes.

Docker didn't always have named volumes. Before there were named volumes, the way to get persistent sharable storage was to create a data volume container that created an anonymous volume, and then run other containers with docker run --volumes-from ... to attach that storage. Now that named volumes exist, there's not a need to do that any more.

I found a solution to my problem. In fact, just as I suspected, there was a missing directory to my PYTHONPATH. It was the directory that contained the gtts package.

Solution: If you have the same problem,

1. Find the package

I looked at that post

1. Add it to sys.path (which will also add it to PYTHONPATH)

Add this code at the top of your script (in my case, the pipelines.py):

Usually this kind of issues (when things works in a terminal but not in crontab), since there is nothing tricky in the crontab entry (you are just calling a executable with no arguments) are due to timing issue. Likely the crontab entry get executed before the network stack is ready. To do a quick test add a delay to that execution prepending sleep 60; to your command, this will delay the execution of 1 minute, which should be enough. Anyway this is not a reliable solution, you will have to user a script o a service which actually check for the network stack.

I was able to finally resolve this after much troubleshooting. Here's what worked.

1. I kept the original setup the same: Sendgrid for SMTP using their python lib (no Postfix or smtplib), using user crontab (using $ crontab -e not $ sudo crontab -e), and using Python 3.7.
2. Apparently the word 'email' in the python script name can cause interpreter issues so I renamed the file to remove the word 'email'. For example, send_noti.py instead of send_email.py
3. I used absolute paths for every call to a file in the python script. I was reading, writing, and executing files in the user directory in my python script as well as sending an email. Those R,W,X commands started erroring out in cron but not when called from outside of cron for some reason, even after renaming the file. Using absolute paths for all references to files fixed that.
4. I also used the absolute path for the python file in the crontab file. For example, * * * * * python3 /home/ec2-user/apps/send_noti.py instead of * * * * * python3 ~/apps/send_noti.py
5. I removed the unnecessary items in the crontab file I had put in before such as redefining the PATH directory.

I hope this helps someone because this took me about 3 weeks to troubleshoot and figure out.

Django needs to serialize your models to make migration files for them. Hence it also needs to serialize most of the attributes you set on the model fields (default included). Currently you define a method and directly call that instead of providing the method as the default, also your method returns a tuple with ScheduleChoice and a boolean.

Django can serialize booleans but not the model instance (for the migration) hence you get an error, not to mention the tuple would have caused an error anyway. You should not call the method and instead just pass the method as the default, also instead of returning the instance return only the pk, also ideally this method should simply be a function:

You need to start celery beat, because that him that will read the database and execute your task.

install : https://github.com/celery/django-celery-beat

so in CLI, you need to execute :