Is it possible to limit concurrency at the flow level without using labels?

Hi @Casey Green, just to make sure: do you use Prefect Server or Prefect Cloud? Concurrency limits is a Cloud-only feature.

We don't provide limiting without tags right now. (2) is simple since you can add the name of the flow as a tag at registration time. (3) is tricky, I agree. Perhaps we can add a way to have an agent be agnostic to tags. Perhaps instead of setting the tag to the name of the flow you could just use an integer from 0-N then have all N tags on the agent. You could also create an agent subclass to retrieve all tags that exist in the backend at initialization time, this is a bit of a hack though and may not be practical at scale either.

You can add a task at the beginning (or at any point of your flow where you think it is crucial that there is no other flow_run of this flow at the same time) of your flow execution that checks that there is no other running flow_run with your flow-id and earlier

created

timestamp. If that condition is not satisfied you can end the flow_run. This might not be pretty, but then you would satisfy all of your points at once

Hi @Anna Geller. We're using cloud (server in dev, but in dev this requirement is not such a big deal). Thanks for the pointers Michael and Julian! I was afraid that the least hack-y solution here was the one you outlined Julian. Thanks again.