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.

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.

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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.

This will pre-fill an automation trigger based on the event you just created.

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.