@Marvin Is there a way to define on_failure hook but not in the @Flow line. Instead define it inside a global function?

Yes, there is a way to define an

on_failure

hook outside of the

@flow

decorator in Prefect. You can utilize the

with_options

method to configure the

on_failure

hook dynamically. Here is an example:

python
from prefect import flow, get_run_logger
from prefect.deployments import Deployment

def err1(flow, flow_run, state):
    print("Preset on_failure hook")

def err2(flow, flow_run, state):
    print("Overwritten on_failure hook")

@flow(on_failure=[err1], name="initial_flow")
def demo_flow():
    logger = get_run_logger()
    <http://logger.info|logger.info>("Flow ran.")
    raise ValueError("An error occurred")

if __name__ == "__main__":
    dynamic_flow = demo_flow.with_options(on_failure=[err2], name="dynamic_flow")
    Deployment.build_from_flow(flow=dynamic_flow, name="test_deployment", apply=True)

In this example,

err1

is defined in the

@flow

decorator but can be overwritten by

err2

using

with_options

. For more information, you can refer to these links: - State Change Hooks - GitHub Issue on `with_options`