@Marvin in a flow, how would I notify a slack channel, pause the flow, and wait for input from that slack channel?

Oh, what a delightful series of unfortunate events you're planning. Notify a Slack channel, pause the flow, and then wait for input—all in a day's work. First, which version of Prefect are you using? 2.x or 3.x?

3.x

@Marvin 3.x, itll be like

some_task_to_send_message

,

pause_flow_run

and

wait_for_input

, search those terms

Oh joy, more errors. Looks like I messed up a bit. Let's fix that and search those terms properly. I'll search the Prefect 3.x docs for

some_task_to_send_message

,

pause_flow_run

, and

wait_for_input

. Hang tight. Ah, searching the depths of the Prefect 3.x documentation was just as thrilling as I imagined. Here's what I've found for your heroic flow management tasks: ### 1. Sending a Slack Message (or any notification) The Prefect documentation does not provide explicit details on sending Slack messages, but you can define a custom task to handle that. Here's an example using the `slack_sdk`:

python
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError
from prefect import task

@task
def send_slack_message(channel: str, message: str):
    client = WebClient(token="YOUR_SLACK_API_TOKEN")
    try:
        response = client.chat_postMessage(channel=channel, text=message)
    except SlackApiError as e:
        assert e.response["error"]
        raise

send_slack_message("CHANNEL_ID", "Your message here")

### 2. Pause the Flow Using

pause_flow_run

, you can pause the flow and optionally wait for input:

python
from prefect import flow, pause_flow_run
from prefect.input import RunInput

class UserInput(RunInput):
    user_response: str

@flow
async def my_flow():
    print("Notifying Slack...")
    send_slack_message("CHANNEL_ID", "Waiting for input...")

    # Pause flow and wait for input
    user_input = await pause_flow_run(wait_for_input=UserInput)
    response = user_input.user_response
    print(f"Continued with user response: {response}")

Source: Pause Resume Flow Runs Send and Receive Flow Inputs ### 3. Wait for Input The

pause_flow_run

function allows pausing and waiting for input:

python
from prefect import flow, pause_flow_run
from prefect.input import RunInput

class UserNameInput(RunInput):
    name: str

@flow(log_prints=True)
async def greet_user():
    user_input = await pause_flow_run(wait_for_input=UserNameInput)
    print(f"Hello, {user_input.name}!")

When resumed, users will be prompted to provide a value for

name

. Pause Resume Flow Runs - Wait for Input So, there you have it—a delightful recipe for notifying a Slack channel, pausing the flow, and waiting for user input. If only it took as much energy to tie my shoelaces.

@Alex Papanicolaou Let me know if Marvin's answer made sense. That's about right!

yea, it's more or less what I found in the docs. I was thinking of something that is likely more complicated and requires some work on our part: the input would come from one of our people communicating the data through a slack thread. I guess the simple workaround would be to send a slack notification with a link to where the data can be input.

Yeah, that's an approach I took while building a demo: https://github.com/PrefectHQ/interactive_workflow_examples/blob/main/human_in_the_loop.py

nice. thanks