What does ` prefect core flow Flow run agent ` do It s uncle Prefect Community #ask-community

What does `*prefect.core.flow.Flow.run_agent*` do?...

Shiyu Gan

04/06/2022, 6:32 AM

What does

*prefect.core.flow.Flow.run_agent*

do? It's unclear from documentation and src code, which seems to say it runs an Agent from inside a Flow, which might be confusing since I was under the impression that Agent runs Flows, not the other way around.

discourse 1

Anna Geller

04/06/2022, 10:59 AM

Prefect Cloud is your orchestration layer or orchestration API telling agents what to do, when, and how. Agents are part of your execution layer, they are polling the orchestration API for work, executing the work, and reporting the state of it to the orchestration API. I don't think it's helpful for you to dive deep into how a flow run gets deployed to an agent under the hood. The best way when you're getting started is to start writing your flows and deploy them.

Anna Geller

04/06/2022, 11:04 AM

and you shouldn't start an agent from inside the flow because the agent must already exist so that it can pick up a flow run Usually here is how it works. You start by writing your flow - `yourflow.py`:

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from prefect import task, Flow


@task(log_stdout=True)
def hello_world():
    print("hello world")


with Flow("hello") as flow:
    hw = hello_world()

You start an agent from one terminal:

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prefect agent local start

Then in another terminal, you register your flow:

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prefect register --project xxx -p /path/to/yourflow.py

Then you can trigger a run on the agent:

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prefect run --project xxx --name yourflowname --watch

and then you should see that your agent picked up this flow run

Kevin Kho

04/06/2022, 1:56 PM

Not super sure, but I don’t think that is hooked up anywhere

Zanie

04/06/2022, 4:13 PM

run_agent

isn’t recommended anymore, but it basically runs the agent inline instead of in a separate process as you would with

prefect agent local start

. It makes sure to include the labels that your flow would need to match.

👍 1

Shiyu Gan

04/07/2022, 3:36 AM

Perhaps let's deprecate?

Zanie

04/07/2022, 4:35 PM

We won’t be making any more breaking changes to the 1.x versions, so we can “deprecate” it but it’ll never be removed.

Zanie

04/07/2022, 4:35 PM

I agree an additional comment in the docstring would be nice at least 🙂

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