Can we get the signature or arguments of a celery task on `task_prerun`

Question

My plan is to log all celery task requests with the arguments they receive s I’m using the following

@task_prerun.connect()
def log_celery_args(task, **kwargs):
    logger.info(f"{task.name} {kwargs['kwargs']}", extra=kwargs['kwargs'])

The problem is this solution doesn’t work when the functions don’t use named parameters.
I can get the values from the kwargs['args'] but I’d like to still have in the extras the format
{arg_name: value}

So my idea was if there’s a way to get the signature of a task or any other way to actually get the parameters needed ?

I already tried the following :

Tried to print all the args of task and task.request to see if I can find it there
Saw a signature function but this one is actually to change it
Tried to play around celery.app.trace to see if I can get it to log with the parameters

Asked By: Dany Y

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Answer 1

From Python 3.8 onwards you can use f"{kwargs=}" to print all keyword arguments.

If positional arguments need to be allowed and logged then the function definition must be adapted as follows:

@task_prerun.connect()
def log_celery_task_call(task, *args, **kwargs):
    logger.info(f"{task.name} {args=} {kwargs=}")

*args in the function definition will catch all positional arguments and **kwargs all keyword arguments. If there are no positional arguments the args variable will be an empty list and if no keyword arguments are supplied kwargs will be an empty dictionary.

See also the Python documentation for function definitions and calls.

Answered By: fabianegli

Can we get the signature or arguments of a celery task on `task_prerun`

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