Prefect Docs

# Run a flow

Looking for the latest Prefect 2 release? Prefect 2 and Prefect Cloud 2 have been released for General Availability. See https://docs.prefect.io/ for details.

Now that you have Prefect installed, you're ready to run a flow.

A flow is a container for tasks and shows the direction of work and the dependencies between tasks.

To run your flow, paste the code below into an interactive Python REPL session:

import prefect
from prefect import task, Flow

@task
def hello_task():
    logger = prefect.context.get("logger")
    logger.info("Hello world!")

with Flow("hello-flow") as flow:
    hello_task()

flow.run()

You should see the following logs after running flow.run() :

[2021-12-17 14:55:05-0500] INFO - prefect.FlowRunner | Beginning Flow run for 'hello-flow'
[2021-12-17 14:55:05-0500] INFO - prefect.TaskRunner | Task 'hello_task': Starting task run...
[2021-12-17 14:55:05-0500] INFO - prefect.hello_task | Hello world!
[2021-12-17 14:55:05-0500] INFO - prefect.TaskRunner | Task 'hello_task': Finished task run for task with final state: 'Success'
[2021-12-17 14:55:05-0500] INFO - prefect.FlowRunner | Flow run SUCCESS: all reference tasks succeeded
<Success: "All reference tasks succeeded.">

You can also save this code to a file called hello_flow.py and run it from a terminal session:

$ python hello_flow.py
[2021-12-17 14:52:24-0500] INFO - prefect.FlowRunner | Beginning Flow run for 'hello-flow'
[2021-12-17 14:52:24-0500] INFO - prefect.TaskRunner | Task 'hello_task': Starting task run...
[2021-12-17 14:52:24-0500] INFO - prefect.hello_task | Hello world!
[2021-12-17 14:52:24-0500] INFO - prefect.TaskRunner | Task 'hello_task': Finished task run for task with final state: 'Success'
[2021-12-17 14:52:24-0500] INFO - prefect.FlowRunner | Flow run SUCCESS: all reference tasks succeeded

If you're running into issues, check that your Python environment is properly set up to run Prefect. Refer to the Prefect Core Installation documentation for further details.

Now you're got a basic flow running locally, we can set up an API and UI using Prefect Cloud and register it.

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