PrefectHQ / prefect

Prefect is a workflow orchestration framework for building resilient data pipelines in Python.
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error when using run_deplyment function in self-hosted prefect server #15780

Open akfmdl opened 1 week ago

akfmdl commented 1 week ago

Bug summary

I set up a self-hosted Prefect server using the Prefect server Helm chart The image needs to be manually specified, so I applied the latest version compatible with that—2.19.9-python3.12-kubernetes. However, when deploying the code via run_deployment, an error occurs if the Python version in the local virtual environment differs, even slightly (e.g., a minor version mismatch). But, when I include the as_subflow=False option in run_deployment(), the error does not occur.

Error location

The error occurs in the create_task_run function of the PrefectClient class, specifically in the following code:

response = await self._client.post(
    "/task_runs/", json=task_run_data.dict(json_compatible=True)
)

Error message

prefect.exceptions.PrefectHTTPStatusError: Client error '409 Conflict' for url 'https://.../api/task_runs/'
Response: {'detail': 'Data integrity conflict. This usually means a unique or foreign key constraint was violated. See server logs for details.'}
For more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/409
13:33:06.296 | ERROR   | Flow run 'just-chameleon' - Finished in state Failed("Flow run encountered an exception. PrefectHTTPStatusError: Client error '409 Conflict' for url 'https://.../api/task_runs/'\nResponse: {'detail': 'Data integrity conflict. This usually means a unique or foreign key constraint was violated. See server logs for details.'}\nFor more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/409")

Version info (prefect version output)

image version: 2.19.9-python3.12-kubernetes
helm chart version: 2024.10.15184517
prefect version 2.19.9

Additional context

No response

jahnavi0102 commented 1 week ago

Reason: When you run a flow or deployment in Prefect, metadata and state information about tasks, flows, and environments (such as Python version, package versions, etc.) are passed between the local environment and the Prefect server.

Why as_subflow=False Avoids the Error: When you include theas_subflow=False option in run_deployment(), you prevent the flow from running as a subflow of the parent flow.

This means: Independent Flow Execution: Prefect treats the deployment as an entirely separate, standalone flow, not linked to any parent flow. This changes how task metadata (including versioning and task run IDs) is handled. Prefect doesn't attempt to reuse or pass metadata between the parent flow and the subflow. No Metadata Inheritance: The task runs don't inherit metadata (like Python versions or task run IDs) from the parent flow, which avoids triggering a conflict in the Prefect server. In essence, the as_subflow=False option isolates the subflow and ensures that it is not dependent on the state or metadata of the parent flow. This effectively avoids the error, but it also means that the flow is now independent and will not share context, state, or any other data with the parent flow.