How to run SlackTask using EnvVarSecret

I’m trying to send a slack message using prefect.tasks.notifications.slack_task.SlackTask and prefect.tasks.secrets.EnvVarSecret to post to Slack.

from prefect import task, Flow
from prefect.tasks.secrets import EnvVarSecret
from prefect.tasks.notifications.slack_task import SlackTask


@task
def notify_slack():
    slack_secret = EnvVarSecret('SLACK_WEBHOOK_URL')
    task = SlackTask(webhook_secret=slack_secret)
    task.run(message='Test slack message')


with Flow('slack test') as slack_flow:
    result = notify_slack()


slack_flow.run()

This throws this exception

ValueError: Local Secret "<Task: SLACK_WEBHOOK_URL>" was not found.

The environment variable SLACK_WEBHOOK_URL has a valid value in it.

How can I use SlackTask and EnvVarSecret to successfully send a message to slack?

[joshmeek]

Ah @petermorrow my bad. The SlackTask needs to be instantiated before it’s called so you could do something like one of the two options below:

from prefect import task, Flow
from prefect.tasks.notifications.slack_task import SlackTask

slack_task = SlackTask(webhook_secret="SLACK_WEBHOOK_URL")

with Flow('slack test') as slack_flow:
    slack_task(message="Test slack message")

slack_flow.run()

from prefect import task, Flow
from prefect.tasks.notifications.slack_task import SlackTask

with Flow('slack test') as slack_flow:
    SlackTask(webhook_secret="SLACK_WEBHOOK_URL", message="Test slack message")()

slack_flow.run()

Also, glad you have it working with a custom task! 😄

[peterth3]

That did the trick, thanks @joshmeek!