@Marvin I want to define a deployment of a flow in code, including a trigger based on a particular event. I want to deploy the flow if it isn't deployed yet, otherwise not to do anything. How do I do this?

To define a deployment of a flow in code with a trigger based on a particular event, and to conditionally deploy the flow if it isn't already deployed, you can follow these steps using Prefect 3.x: 1. Define the Deployment: You can create a deployment using the

serve

or

deploy

method in Python. This will allow you to specify the deployment configuration in code. 2. Set Up Event Triggers: Use Prefect's event-driven deployment triggers to configure the deployment to run based on specific events. You can define triggers using classes such as

DeploymentEventTrigger

,

DeploymentMetricTrigger

,

DeploymentCompoundTrigger

, and

DeploymentSequenceTrigger

. These can be imported and used to create automations linked to specific events. 3. Check Deployment Status: Before deploying, you might want to check if the deployment already exists. This can be done by querying Prefect's API or using a condition in your code to determine if deployment is necessary. Here's a basic example of how you might set this up:

python
from prefect import flow, serve, DeploymentEventTrigger

@flow
def my_flow():
    # Your flow logic here
    pass

# Define an event trigger
event_trigger = DeploymentEventTrigger(event="external.resource.pinged")

# Serve the deployment with the trigger
serve(
    flow=my_flow,
    triggers=[event_trigger],
    # Add additional deployment configuration as needed
)

Resources: - Deployment Overview - Automation with Deployment Triggers This approach allows you to manage deployments programmatically and ensure they are only created when necessary. If you need to check if a deployment already exists, you may need to interact with the Prefect API directly for a more advanced setup.