I want to set up a Slack integration that sends a message (via webhook) whenever a task or story is flagged as 'Impediment'. I have tried applying a JQL filter of "Flagged = 'Impediment'" to the webhook, but this will only fire for tasks which are already flagged, as opposed to those that whose 'Flagged' attribute is changing.
How can I achieve this?
I have the same challenge. Using a status is a poor workaround for flagging an issue, it removes all the flagging functionality from the Scrum boards and where we use In Build > In Test status's it would remove the distinction of where in the process the issue has been impeded.
Have you considered creating a status named 'Impediment' instead of flagging?
That way, you will be able to fire the webhook on transitioning the issue to said status.
In fact, we have said status on our instance as it is a convenient one on itself.