@Marvin, how can I configure a REST Endpoint in Prefect to use with a webhook from another system?

it looks like your tag got messed up somehow

✅ thought for 540.3 seconds

but to answer the question, you set up a webhook template that transforms the payload into a prefect event that can then be used to trigger automations (like run_deployment) in prefect

thank you @Nate. Is that possible with Prefect OSS?

webhooks are not available at this time in OSS unfortunately

There are any workarounds?

however you can always have a sidecar service that receives webhooks and calls emit_event

thank you!

Great question! There are two good ways to expose a “REST endpoint” for external webhooks to trigger Prefect runs: 1) Prefect Cloud Webhooks + Automations (no custom server needed) - Create a webhook in Prefect Cloud. It gives you an HTTPS URL like

<https://api.prefect.cloud/hooks/<id>>

. - The webhook uses a Jinja template to turn the incoming HTTP request (method/headers/body) into a Prefect Event. - Create an Automation with an Event trigger that listens for that event and adds a Run Deployment action to start your deployment. Use Jinja to map fields from the event payload into your flow parameters. Minimal example: - Webhook template (UI → Webhooks):

{
  "event": "external.webhook.received",
  "resource": {
    "prefect.resource.id": "external.webhook"
  },
  "payload": {
    "user_id": "{{ body.user_id }}",
    "action": "{{ body.action }}"
  }
}

- Automation (UI → Automations) with: - Trigger: Event, expect

external.webhook.received

- Action: Run deployment, parameters: - `user_id`:

{{ event.payload.user_id }}

- `action`:

{{ event.payload.action }}

- Security options: - Require a service account API key on the webhook and have the external system send `Authorization: Bearer <key>`; Prefect strips this header from templates for safety. - If you can’t send auth headers, the webhook URL is opaque; you can rotate it when needed. Docs: - Webhooks concepts - Create a webhook - Automations concepts - Creating automations 2) Call Prefect’s REST API directly to create a flow run (Cloud or OSS) If your external system can include an Authorization header, you can skip webhooks/automations entirely and call the deployment’s “create flow run” endpoint. - Cloud URL shape:

POST <https://api.prefect.cloud/api/accounts/<ACCOUNT_ID>/workspaces/<WORKSPACE_ID>/deployments/<DEPLOYMENT_ID>/create_flow_run>
Authorization: Bearer <PREFECT_API_KEY>
Content-Type: application/json

- OSS URL shape (default port may be 4200 in local dev or 8080 in some setups):

POST http://<your-server-host>:<port>/api/deployments/<DEPLOYMENT_ID>/create_flow_run
Content-Type: application/json

- Example curl (Cloud):

curl -X POST \
  "<https://api.prefect.cloud/api/accounts/<ACCOUNT_ID>/workspaces/<WORKSPACE_ID>/deployments/<DEPLOYMENT_ID>/create_flow_run>" \
  -H "Authorization: Bearer pnu_XXXXXXXXXXXXXXXX" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "triggered-from-webhook",
    "parameters": {
      "user_id": "user-123",
      "action": "process"
    },
    "tags": ["webhook"]
  }'

Docs: - REST: create_flow_run_from_deployment - REST API overview (Cloud URL shape) - Python client alternatives: - PrefectClient.create_flow_run_from_deployment - run_deployment helper Which should you use? - Use Cloud Webhooks + Automations when the external system cannot add a Bearer token, or you want to route through Prefect events/filters and reuse Jinja templating to map webhook payloads to parameters. - Use the REST API directly when the external system can authenticate with a header and you just want to start a run immediately. Notes and gotchas - Webhooks are a Prefect Cloud feature; OSS should use the REST API directly (or front with your own lightweight receiver). - Automations can be managed via UI or API; the CLI currently supports listing/inspecting/pausing/resuming/deleting (not creating).