This page shows you how to quickly set up a webhook using the Prefect Cloud UI, invoke it, and create an automation based on the received event.

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Trigger an Automation from an External Event

Here’s how to set up a webhook and trigger an automation using the Prefect Cloud UI.

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1. Create a Webhook in the UI

Navigate to the Webhooks page in Prefect Cloud and click Create Webhook. You will need to provide a name for your webhook and a Jinja2 template. The template defines how the incoming HTTP request data is transformed into a Prefect event. For example, to capture a model ID and a friendly name from the request body: 
{
    "event": "model-update",
    "resource": {
        "prefect.resource.id": "product.models.{{ body.model_id}}",
        "prefect.resource.name": "{{ body.friendly_name }}",
        "run_count": "{{body.run_count}}"
    }
}
This template will look for model_id, friendly_name, and run_count in the body of the incoming request. Create a webhook in the Prefect Cloud UI, showing the template editor. After saving, Prefect Cloud will provide you with a unique URL for your webhook.

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2. Invoke the Webhook Endpoint

Use any HTTP client to send a POST request to the unique URL provided for your webhook. Include the data you want to pass in the request body. For the example template above: 
curl -X POST https://api.prefect.cloud/hooks/YOUR_UNIQUE_WEBHOOK_ID \
  -d "model_id=my_model_123" \
  -d "friendly_name=My Awesome Model" \
  -d "run_count=15"
Replace YOUR_UNIQUE_WEBHOOK_ID with your actual webhook ID.

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3. Observe the Event in Prefect Cloud

After invoking the webhook, navigate to the Event Feed in Prefect Cloud. You should see a new event corresponding to your webhook invocation. Event feed in Prefect Cloud showing a newly created event from a webhook.

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4. Create an Automation from the Event

From the event details page (click on the event in the feed), you can click the Automate button. Event details page with the Automate button highlighted. This will pre-fill an automation trigger based on the event you just created. Automation trigger definition pre-filled from a webhook event. Click Next to define the action(s) this automation should perform, such as running a deployment or sending a notification.

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Troubleshooting Event Reception

If you’ve invoked your webhook but don’t see the expected event in Prefect Cloud, or the event data isn’t what you anticipated:
  • Check the Event Feed: Look for any events related to your webhook, even if they don’t match your exact expectations.
  • Look for prefect-cloud.webhook.failed events: If Prefect Cloud encountered an error processing the webhook (e.g., an invalid template or malformed request), it will generate a prefect-cloud.webhook.failed event. This event contains details about the received request and any template rendering errors.
  • Verify your request: Double-check the URL, HTTP method, headers, and body of the request you sent to the webhook.
  • Review your template: Ensure your Jinja2 template correctly accesses the parts of the HTTP request you intend to use (e.g., body.field_name, headers['Header-Name']).
For more in-depth troubleshooting of webhook configuration and template rendering, see Troubleshooting Webhook Configuration in the Concepts documentation.

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Further reading

For more on webhooks, see the Webhooks Concepts page.