Amazon SQS and celery events (not JSON serializable)

Question

I was looking today into Amazon SQS as an alternative approach to installing my own RabbitMQ on EC2 instance.

I have followed the documentation as described here

Within a paragraph it says:

SQS does not yet support events, and so cannot be used with celery events, celerymon or the Django Admin monitor.

I am a bit confused what events means here. e.g. in the scenario below I have a periodic task every minute where I call the sendEmail.delay(event) asynchronously.

e.g.

@celery.task(name='tasks.check_for_events')
@periodic_task(run_every=datetime.timedelta(minutes=1))  
def check_for_events():        
    now = datetime.datetime.utcnow().replace(tzinfo=utc,second=00, microsecond=00)
    events = Event.objects.filter(reminder_date_time__range=(now - datetime.timedelta(minutes=5), now))
    for event in events:        
        sendEmail.delay(event)

@celery.task(name='tasks.sendEmail')
def sendEmail(event):
    event.sendMail()

When running it with Amazon SQS I get this error message:

tasks.check_for_events[7623fb2e-725d-4bb1-b09e-4eee24280dc6] raised exception: TypeError(' is not JSON serializable',)

So is that the limitation of SQS as pointed out in the documentation or am I doing something fundamentally wrong? Many thanks for advice,

Answer 1

I might have found the solution. Simply refactor the sendMail() function inside event into the main task therefore there won't be any need to parse the object into json:

@celery.task(name='tasks.check_for_events')
@periodic_task(run_every=datetime.timedelta(minutes=1))  
def check_for_events():    
    now = datetime.datetime.utcnow().replace(tzinfo=utc,second=00, microsecond=00)
    events = list(Event.objects.filter(reminder_date_time__range=(now - datetime.timedelta(minutes=5), now)))
    for event in events:        
        subject = 'Event Reminder'
        link = None
        message = ... 
        sendEmail.delay(subject, message, event.user.email)


@celery.task(name='tasks.sendEmail')
def sendEmail(subject, message, email):
    send_mail(subject, message, settings.DEFAULT_FROM_EMAIL, [email])

This works both with Rabbitmq and Amazon SQS