Hey community! Is there a way to run a flow inside...
# ask-communitya
Avi A
05/05/2020, 7:45 PMHey community! Is there a way to run a flow inside a different flow? I mean suppose I have an existing flow and want to trigger it as part of a different flow, without specifying the flow again. Is there a way to do that? e.g. a Task that wraps an existing flow? Preferably a flow that is registered to the orchestration server?
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Zachary Hughes
05/05/2020, 8:07 PMHi @Avi A! If I'm understanding properly, you want to kick off a new flow run from within a flow. While I wouldn't recommend wrapping an existing flow in a task (things can get wonky that way), you can use your orchestration layer to use the Flow Run Task and kick off a new flow run.
https://docs.prefect.io/api/latest/tasks/cloud.html#flowruntask
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Avi A
05/05/2020, 10:08 PMgot it, thanks. so I understand this functionality works only with cloud, and not with the core server?
Avi A
05/05/2020, 10:09 PMrelated: can I specify a return value for a flow, the same way we do it for tasks? I looked in the docs and couldn’t find something about it
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Zachary Hughes
05/05/2020, 10:41 PMActually, I think you've spotted a chance for us to improve our documentation! Looks like the docs I linked are pre-server, but I just tested and you can use the
FlowRunTaskfr_test = FlowRunTask(flow_name="hello-flow")👏 1
Zachary Hughes
05/05/2020, 10:41 PMAnd I'm unsure of return values for flows-- let me poke around and see if I can find an answer for you!
Edit: following up, it looks like there's not currently a way to specify a return value for a flow.
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Avi A
05/05/2020, 10:54 PMthanks a lot, I’ll give it a go soon!
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Zachary Hughes
05/05/2020, 10:55 PMSounds good! I'm a fan of this task-- hope you are too. 🙂
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Avi A
05/05/2020, 10:57 PMthanks for following up! actually looking deeper into the doc and the source code it seems that this task only triggers the flow, but doesn’t wait for it
Avi A
05/05/2020, 10:57 PMit means that if I put it as part of my second flow it doesn’t really wait for it to finish, and the downstream tasks can’t rely on its artifacts
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Zachary Hughes
05/05/2020, 10:59 PMThat's correct-- it'll send an API call to your orchestration layer to create a new, scheduled flow run, but will not wait for that flow run.
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