Idempotency

You can set an idempotency key for a workflow to guarantee it executes only once, even if called multiple times with that key. This is especially useful if your operations have side effects like making a payment or sending an email.

An idempotency key can be any string, but we recommend using UUIDs. Idempotency keys are required to be globally unique for your application.

Use SetWorkflowID to set an idempotency key for a workflow. This will also set the workflow ID of that operation. For example:

@DBOS.workflow()
def example_workflow():
    DBOS.logger.info(f"I am a workflow with ID {DBOS.workflow_id}")

# This sets the ID of the workflow to the supplied idempotency key
with SetWorkflowID("very-unique-id"):
    example_workflow()

If you're serving HTTP requests with FastAPI or Flask, you can make any request idempotent by setting its dbos-idempotency-key header field. DBOS will automatically parse that header and assign the idempotency key to the first workflow called from the request.