@Marvin how can I develop and debug my flows locally withou using the prefect server, just running the python file “as is”.

Before I provide you with guidance, could you please confirm which version of Prefect you are using? Prefect 2.x and Prefect 3.x have different methods and tools for developing and debugging flows locally.

@Marvin using version 3.10

To develop and debug your flows locally in Prefect 3.10, you can directly run your Python script without requiring the Prefect server. Here's how you can do it: 1. Define Your Flow: Start by defining your flow using the

@flow

decorator from Prefect within your Python script. Here's a simple example:

python
   from prefect import flow

   @flow
   def say_hi():
       print("Hi, I'm a Prefect flow!")

   if __name__ == "__main__":
       say_hi()

2. Running the Flow: You can simply run your Python file as you would with any other Python script. Use the command line to execute your script:

bash
   python your_script.py

3. Serve and Trigger Flows: If you want to experiment with more advanced deployment features locally, Prefect allows you to serve your flow. You can use the

serve

method for this purpose:

python
   if __name__ == "__main__":
       say_hi.serve(name="my-deployment")

This command will start your flow and allow it to poll for scheduled runs locally. 4. Using Workers: For executing flows using workers without a Prefect server, define the worker pool and start a worker:

bash
   prefect worker start --pool local

Ensure to set up your flow deployment with

work_pool_name="local"

and you can manage it locally as desired. The above approach will let you develop and test Prefect flows on your machine without interacting with Prefect Cloud or a Prefect server. For further details, you can refer to the Prefect 3.x documentation here and here.

@Marvin unfortunately I am getting an error with “just running the file”: No Prefect API URL provided. Please set PREFECT_API_URL to the address of a running Prefect server.

It looks like you're encountering issues because Prefect 3.x expects an API URL to be set, which is typically required for connecting to a Prefect server or cloud instance. However, you can run Prefect flows locally without specifying an API URL by ensuring that your Prefect profile is set to use local execution. Here's how you can work around this: 1. Set Up Local Profile: Ensure your local Prefect profile is appropriately configured to not require a server. Typically, local profiles should disable server connections by default, but it's good to confirm. Use the Prefect CLI to check your current profile settings:

bash
   prefect profile ls

Then, make sure you are using a profile that does not require connection to a server. You can create or switch to a local profile:

bash
   prefect profile create local
   prefect profile use local

2. Run the Script: Once your Prefect profile is set to local, try running your Python script again. This configuration should allow you to execute Prefect flows locally without setting a

PREFECT_API_URL

. For further details, you might also want to delve into their settings and profiles documentation.

@Marvin doesn’t help: prefect profile use local ⠋ Checking API connectivity... Error connecting to Prefect API URL

It seems like Prefect 3.10.0 has some issues around setting up local executions without requiring an API URL. Given that the latest release notes for Prefect indicate a fix related to flow serving, updating to the latest version might resolve some of these problems. Here's what you can do now: 1. Update Prefect: Make sure your Prefect version is up-to-date to benefit from recent bug fixes. You can do this with:

bash
   pip install --upgrade prefect

2. Setting Up a Local API: If the above steps don't help, you can consider running a lightweight local API for development purposes. Prefect’s default setup expects this, even when not directly interfacing with cloud or server options. 3. Using Environment Variables: You can set up a local environment variable to bypass the API check temporarily. Use it at your discretion, particularly if examining potential issues.

bash
   export PREFECT_API_URL="<http://localhost>"

If these solutions do not resolve your issue, consider keeping an eye on the Prefect GitHub repository for updates or potential open issues related to running flows locally. For a detailed overview of settings, profiles, and managing Prefect deployments locally, refer to the Prefect 3.0 settings documentation.