@Marvin what is the best way to ensure only one flow-run with a certain name is running at a time? For example if a flow-run called "handsome-walrus" is running and another flow-run called "handsome-walrus" is launched, the 2nd will fail or not start at all.

To ensure that only one flow run with a certain name is running at a time, you can utilize concurrency limits. While the extracted documents do not provide the specific answer to enforcing uniqueness by the flow run name, they do briefly mention the concept of concurrency limits which are enforced at the work pool and/or work queue level. To implement a solution to your requirement, you might consider setting a concurrency limit of 1 on a work queue that is specific to the flow run name "handsome-walrus." This way, whenever a flow run with that name is attempted to be launched while another is already running, the new one would be prevented from starting until the running instance finishes. The specifics of setting concurrency limits can be normally managed through: - Prefect CLI - Prefect API using the

PrefectClient

Python client - Prefect server UI or Prefect Cloud If there was an example of setting concurrency limits based on flow run names, I would have provided it, but I do know that doc URLs can bring delight: - Flow Concepts - Task Concepts - Task Runners For a detailed guide on how to configure concurrency limits for flow runs using work pools and work queues, you may refer directly to the Prefect documentation or seek guidance through the Prefect community or support channels. Unfortunately, I can't search for concurrency limit settings based on flow run name specifics with my current capabilities.

@Marvin I want to be able to run many flow-runs concurrently within the same workpool but ensure that no flow-run of the same name is actively running before launching another of that name

The search for GitHub issues related to flow run concurrency with the same name did not yield results directly addressing the question of ensuring no duplicate flow run names are actively running. The issues found broadly discuss problems related to serialization of Pydantic models, an example of a concurrency context manager not working as expected, and global concurrency limits not being applied when using the

DaskTaskRunner

. These issues seem to be tangential to the specific question asked. If the capability of enforcing the uniqueness of flow run names is a feature within Prefect, it is not documented or explicitly dealt with in the open GitHub issues. This suggests that this feature may not be directly supported as of now, or it may not be a common enough requirement to have surfaced in issues or documentation. For real-time assistance or deeper insights regarding this specific need, it would be best to reach out to the Prefect community or support channels directly, as they could offer workarounds or let you know if such a feature is in the roadmap. Still, if you're looking to avoid duplicate flow run names within the same work pool and ensure one hasn't ended before starting another with the same name, it could perhaps be implemented with custom logic in your flows that checks the active runs before launching new ones. Unfortunately, without explicit support in Prefect for this functionality, such a solution would need to be manually designed and implemented.

@Marvin is this something I could use automations for?

Based on the information found in the Prefect documentation on automations, it seems that automations might provide a framework to enforce only one flow run with a particular name at a time. Automations in Prefect allow you to specify actions the system should take based on various trigger conditions, such as changes in a flow run's state or the absence of such events. You can configure triggers proactively to fire in the absence of an expected event. While the document excerpts did not explicitly mention an automation that can enforce unique flow run names, automations can potentially be configured to check for an existing flow run with a given name and take appropriate actions if a duplicate name is detected. For instance, you might be able to create an automation that: - Triggers when a new flow run starts. - Checks if there is an existing active flow run with the same name. - Cancels the newly initiated flow run if a duplicate is detected. However, the specifics of the automation configuration needed to enforce this are not detailed in the excerpts. Below are the links to the relevant documentation pages which can be studied for a more detailed understanding of how to possibly set up such an automation: - Automations Guide - Automations Concepts Keep in mind that for detailed guidance on how to implement this specific logic, you may need to consult the full extent of Prefect's documentation on automations to understand if and how this setup could be achieved. If the documentation and available resources do not suffice, reaching out to the Prefect community or support directly would be the route to get specific guidance or confirmation on whether this is a supported automation scenario.