@Marvin if i want to start a flow via rest api, do i still need a deployment ?

Yes, in Prefect 3.x, you still need a deployment to start a flow via the REST API. Deployments are used to manage and execute flows, and they provide the necessary configuration and context for running flows. You can create a deployment using a

prefect.yaml

file or through Python code with

flow.deploy

. Here's a brief overview of the process: 1. Create a Deployment: Use a

prefect.yaml

file or Python code to define your deployment. 2. Retrieve Deployment ID: Use the CLI to list deployments and get the

deployment_id

. 3. Trigger via REST API: Use the deployment ID in your API calls to start flow runs. For more details, you can refer to the Prefect documentation on deployments and automations. If you have any specific scenarios or configurations in mind, feel free to share them.

@Marvin how to automate to start the flow when i receive a custom event from external service ?

To automate the start of a flow when receiving a custom event from an external service, you can utilize Prefect's webhook capabilities. Here’s a concise guide: 1. Webhooks in Prefect Cloud: Prefect Cloud allows you to set up webhooks that can receive events from external systems. Each webhook has a unique URL endpoint that can transform incoming requests into Prefect events. 2. Configure Webhooks: - API: Use the Prefect Cloud API to manage webhooks. Authenticate your API calls as you would normally with Prefect Cloud. - UI: You can also create and manage webhooks via the Prefect Cloud UI. - CLI: Use the

prefect cloud webhook

command group to manage webhooks through the CLI. 3. Automation Setup: - Define a trigger condition using the webhook to start the flow. This involves setting up the webhook to listen for specific events from your external service. - Configure actions in Prefect Automations to start the flow run when the webhook event is received. For further details, you can refer to the webhook triggers documentation and automations and triggers documentation. This setup allows you to respond dynamically to events from external services, streamlining your workflow automation.

@Marvin in a self hosted env

In a self-hosted Prefect environment, automating the start of a flow when receiving a custom event from an external service requires a bit of manual setup, as webhooks are typically a Prefect Cloud feature. However, here's a general approach you can take: 1. Custom Endpoint: You need to set up a custom HTTP endpoint to receive events from your external service. This can be done using any web framework like Flask or FastAPI. 2. Trigger Flow Runs: - Once your endpoint receives an event, use the Prefect Python client to trigger a flow run programmatically. - You can use the

prefect.client

module to interact with your Prefect server and start a flow run. 3. Deployment: - Ensure your flow is deployed and accessible in your self-hosted environment. You will need the deployment ID to start the flow run. 4. Security: - Implement security measures for your custom endpoint, such as authentication and validation of incoming requests. 5. Configuration: - Use environment variables or configuration files to manage sensitive information like API keys or deployment IDs. This setup involves a bit more manual work compared to Prefect Cloud but provides flexibility to integrate with external services in a self-hosted environment. For more details on automations and triggers, you can refer to the Prefect documentation.

@Marvin how to trigger a flow via rest api ?

To trigger a flow via the REST API in Prefect, you generally need to interact with the deployment of the flow. Here's a simplified process to start a flow run using the REST API: 1. Ensure Deployment: Make sure your flow is deployed. You will need the deployment ID for this process. 2. API Endpoint: Use the Prefect API to trigger the flow run. The endpoint typically looks like this:

POST /api/deployments/{deployment_id}/create_flow_run

Replace

{deployment_id}

with your actual deployment ID. 3. Authentication: Ensure you have the necessary API keys or tokens to authenticate your requests. 4. Request Body: You can include parameters in the request body if your flow requires input parameters. 5. Example Request:

bash
   curl -X POST "<http://your-prefect-server/api/deployments/{deployment_id}/create_flow_run>" \
   -H "Authorization: Bearer YOUR_API_KEY" \
   -H "Content-Type: application/json" \
   -d '{
         "parameters": {
           "param1": "value1",
           "param2": "value2"
         }
       }'

6. Response: The response will contain details about the triggered flow run, including its ID, which you can use to track its status. For further details, you may need to refer to the specific REST API documentation for your Prefect server setup, as configurations can vary in self-hosted environments.

@Marvin how to send a json as a parameter input for the flow

To send a JSON object as a parameter input to a flow in Prefect, you can follow these steps: 1. Define Flow Parameters: - Define your flow to accept parameters using Python's function arguments. Prefect supports type hints, so you can use Pydantic models to define complex structures like JSON. 2. Use Pydantic Models: - If your input is complex, consider using Pydantic models. Define a Pydantic model that matches the structure of your JSON data. 3. Pass JSON as Parameters: - When triggering the flow, pass the JSON data as a dictionary in the parameters. Prefect will handle the serialization and deserialization for you. 4. Example:

python
   from prefect import flow
   from pydantic import BaseModel

   class MyParams(BaseModel):
       key1: str
       key2: int

   @flow
   def my_flow(params: MyParams):
       print(params)

   # Trigger the flow with JSON data
   my_flow(params={"key1": "value1", "key2": 123})

5. Trigger via API: - If you're using the API, include the JSON data in the request body as a dictionary under the

parameters

key. For more details, you can check the Prefect documentation on flow inputs. This approach allows you to pass structured data efficiently and ensures type safety with Pydantic models.

@Marvin give example how to call via API with json param

To call a Prefect flow via the API with JSON parameters, you typically need to interact with the deployment endpoint. Here’s an example using

curl

to illustrate how you might do this: 1. Identify the Deployment ID: Ensure you have the deployment ID of the flow you want to trigger. 2. Craft the API Request: - Use the

POST

method to send a request to the deployment endpoint. - Include your JSON parameters in the request body. 3. Example API Call:

bash
   curl -X POST "<http://your-prefect-server/api/deployments/{deployment_id}/create_flow_run>" \
   -H "Authorization: Bearer YOUR_API_KEY" \
   -H "Content-Type: application/json" \
   -d '{
         "parameters": {
           "param1": "value1",
           "param2": 123
         }
       }'

### Explanation: -

{deployment_id}

: Replace this with the actual deployment ID. -

YOUR_API_KEY

: Replace with your actual API key for authentication. -

parameters

: This is where you include your JSON data. Ensure the JSON structure matches the expected input for your flow. This example assumes you have a self-hosted Prefect server. Adjust the URL and authentication details according to your setup. If you have specific requirements or issues, let me know!