@Marvin I defined a flow as a function in a python module, that I install in a custom docker image. How should I deploy this flow? I run into issues with relative imports prefect.exceptions.ScriptError: Script at 'my_module/flow.py' encountered an exception: ImportError('attempted relative import beyond top-level package')

You're encountering a common issue when deploying Prefect flows in a custom Docker image with relative imports. The problem stems from how Python handles module imports within the context of Docker and Prefect. Here's a step-by-step guide to help you address and potentially resolve the issue: 1. Avoid Relative Imports: Replace relative imports with absolute imports in your Python module. Relative imports can cause issues when the module structure isn't preserved exactly as expected. Instead of:

python
   from ..some_module import some_function

Use:

python
   from my_module.some_module import some_function

2. Ensure Proper Module Path: When running your flow, ensure that the module's path is correctly included in the Python path. Example Dockerfile snippet:

dockerfile
   ENV PYTHONPATH="/path/to/your/module:${PYTHONPATH}"

3. Check Docker Build Context: Ensure the Docker build context includes the directory containing your module. You might need to adjust the Dockerfile to copy the complete module directory. Example:

dockerfile
   COPY . /app
   WORKDIR /app

4. Deployment Configuration: When deploying your flow, specify the module path correctly. Here's an example of how you can deploy a flow using Prefect's CLI with an absolute path:

bash
   prefect deployment build -n my_flow -q default -p /path/to/your/module/flow.py

5. Review GitHub Issues for Reference: - Circular Import on Deployment (again) - ModuleNotFoundError when running deployed flows These suggestions should help you address the issue. If you encounter further problems, reviewing the linked GitHub issues might provide additional insights. For any unusual scenarios or persistent issues, consider reaching out on the Prefect Slack community or opening a new GitHub issue.

@Marvin how to do that in python SDK?

To deploy a Prefect flow using the Python SDK with a custom Docker image, you can follow these steps: 1. Define your flow in a Python script, ensuring you use absolute imports:

python
   from my_module.some_module import some_function
   from prefect import flow

   @flow(log_prints=True)
   def my_workflow():
       some_function()
       print("This is my flow")

   if __name__ == "__main__":
       my_workflow()

2. Build the Docker image, including your flow and its dependencies: Dockerfile example:

dockerfile
   FROM python:3.9-slim

   # Set the working directory
   WORKDIR /app

   # Copy the requirements file and install dependencies
   COPY requirements.txt .
   RUN pip install -r requirements.txt

   # Copy the entire module into the container
   COPY . .

   # Ensure the module path is in the PYTHONPATH
   ENV PYTHONPATH="/app:${PYTHONPATH}"

   # Run the flow script (if needed, change this to your flow script)
   CMD ["python", "my_workflow.py"]

3. Build the Docker image (assuming you are in the directory containing your Dockerfile):

bash
   docker build -t my_custom_image:latest .

4. Use the Prefect Python SDK to create and deploy the flow: Ensure you have Prefect installed in your environment:

bash
   pip install prefect

Then, create your deployment script:

python
   from prefect.deployments import Deployment
   from prefect.infrastructure.docker import DockerContainer

   from my_workflow import my_workflow

   # Define the Docker infrastructure
   docker_infrastructure = DockerContainer(
       image="my_custom_image:latest"
   )

   # Create the deployment
   deployment = Deployment.build_from_flow(
       flow=my_workflow,
       name="my-workflow-deployment",
       infrastructure=docker_infrastructure
   )

   if __name__ == "__main__":
       deployment.apply()

This script defines the deployment configuration using your custom Docker image and applies the deployment. 5. Run the deployment script:

bash
   python deployment_script.py

This setup will ensure your flow runs within the custom Docker image, avoiding issues with relative imports. You can find more code examples and information using Prefect's official examples.