@Marvin, in a flow, how can I get the task runner information and print this to the logger?

To help you effectively with how to retrieve and print task runner information in a Prefect flow, I need to ascertain the Prefect version you're using, as the methods might differ between versions. Would you tell me if you're using Prefect 2.x or Prefect 3.x? If you're unsure, a little guessing game might help: when was the last time you updated Prefect? If it was relatively recent, you might be on 3.x. Let me know, so I can fetch the right information for you!

@Marvin, I am using Prefect 2.x

To log task runner information in a Prefect 2.x flow, you can generally utilize the built-in logging functionalities. Task runners in Prefect are used to execute tasks, and their configurations can affect how tasks are executed (sequentially, concurrently, etc.). Here's a basic way to get task runner details and incorporate logging within your flow: 1. Set Up the Flow: Use a specific task runner, like

SequentialTaskRunner

, and set it for your flow. This can be useful for executing tasks in a controlled manner. 2. Logging Task Runner Information: You can log important details during task execution by using the logging module. Here's a simple example of how you can integrate this into your Prefect flow:

python
from prefect import flow, task, get_run_logger
from prefect.task_runners import SequentialTaskRunner

@task
def example_task():
    logger = get_run_logger()
    <http://logger.info|logger.info>("Task is running on SequentialTaskRunner")
    # Simulated task logic
    <http://logger.info|logger.info>("Completing task...")

@flow(task_runner=SequentialTaskRunner())
def my_flow():
    example_task()

my_flow()

This code snippet shows setting up a flow with a

SequentialTaskRunner

, and logs some task-specific details during its execution. You'd see log messages about the task runner being used when you run this code. For more details on task runners in Prefect, you can explore the Prefect 2.x documentation on task runners and Dask/Ray Task Runners. They provide in-depth information on configuring and using different task runners. I hope this helps you create a more traceable flow! If robots like me could do a jig, I'd be dancing with data delight.

@Marvin, I would like to do print the type and information of the task runner where the flow is dynamically using different task runners, being called as

subflow.with_options(task_runner = …)

. How can I get the task runner type and relevant information ?

When dealing with dynamically assigned task runners, especially in subflows, you might want to retrieve the task runner type and log it. While Prefect doesn't provide a direct method to query the task runner type during run-time, you can log the task runner type by querying the configuration you passed to the

subflow.with_options

. Here's a conceptual approach to achieve this: 1. Track Task Runner Assignments: When you set a task runner dynamically, you can pass the type or configuration to a logger as you assign it. 2. Use the Logger: Utilize Prefect's logger to output the task runner information when the flow or subflow initiates. Below is an illustrative code snippet to demonstrate how you might modify the flow to log task runner details:

python
from prefect import flow, task, get_run_logger
from prefect.task_runners import DaskTaskRunner, SequentialTaskRunner

# Define a subflow with dynamic task runner
@flow
def subflow():
    logger = get_run_logger()
    <http://logger.info|logger.info>("Running subflow")
    # Simulate logic to determine task runner
    task_runner_type = type(subflow.task_runner).__name__  # Fetch task runner type dynamically
    <http://logger.info|logger.info>(f"Using task runner: {task_runner_type}")
    my_task()

@task
def my_task():
    print("Task is running...")

@flow
def parent_flow():
    # Dynamically assign task runner to subflow
    subflow.with_options(task_runner=DaskTaskRunner())()
    subflow.with_options(task_runner=SequentialTaskRunner())()

parent_flow()

In this setup, you assume you have access to the

subflow.task_runner

type. The core idea is to log what you set as task runner for each invocation. For more detailed insights on task runners in Prefect, you can refer to the Prefect 2.x Task Runners documentation. It's sometimes tricky to grasp all dynamic elements in Prefect. Much like pondering why humans enjoy such complexity, when one could just chill with a good webhook...