To perform an action on specific task states, such as on failure before retries, you can use state change hooks. However, the initial search didn't reveal explicit documentation in Prefect about hooks that trigger before each task retry - it mainly demonstrates hooks for a flow run failure and discusses concepts and best practices. According to the search results, state change hooks can indeed perform actions when tasks change states, including failure. This behavior can commonly be used to send notifications when a task enters a failed state. While the exact documentation example that covers your need wasn't found, I can guide you through creating a hook that could perform an action on each task retry after a failure. Here's a general approach to implement a task hook in Prefect: 1. Define a hook function that should run when your task enters a specific state, like

Retrying()

or

Failed()

. 2. Use the

state_handlers

parameter of the

@task

decorator to attach your hook function to the task. 3. Inside your hook function, you can implement any action you desire, such as waiting for another event or sending a notification. Since the provided documentation excerpts and the code example didn't contain the information we're looking for to fully answer your question, you may need to dig deeper into the Prefect documentation or community examples involving

state_handlers

, specifically for task retries. Alternatively, you can look into Prefect's task retry mechanism itself and see if it's possible to integrate hooks directly within the retry strategy or attach handlers that are triggered upon every retry attempt due to failure. To get started with hooks in Prefect, here is a simplified Python example based on the concept of state change hooks:

python
from prefect import flow, task
from prefect.engine.state import Retrying

@task(state_handlers=[your_retry_handler])
def my_task():
    # your task implementation

def your_retry_handler(task, old_state, new_state):
    if isinstance(new_state, Retrying):
        # Perform your action here, such as sending a notification
        pass
    return new_state

@flow
def my_flow():
    my_task()

if __name__ == "__main__":
    my_flow()

Replace

your_retry_handler

with the appropriate function that defines the action to take on each retry due to failure. Please note that this is a general guide, and the actual implementation may vary according to Prefect's current API and best practices. For more specific examples, you can browse through Prefect's community code examples on GitHub, forums, or consult the official documentation on state change hooks for detailed guidance.