Webhook

Introduction

To ensure timely updates and notifications, PiAPI offer webhook services integrated with our Unified API Schema.
When you create a task, you can specify a webhook endpoint. Our API service will then send an HTTP POST request to this URL whenever a task succeeds or fails.

Webhooks: Use Cases


Since input and output data (including any files) are automatically deleted after a set period, webhooks allow you to capture all metadata for completed tasks. This enables you to store the data in a database or save the output files to persistent storage before they are deleted.


Some tasks may take several minutes to complete. By using a webhook handler, you can send notifications—such as an email or a Slack message—when a task is completed.


Webhooks can capture the output of one long-running task and feed it into another model as input, enabling seamless automation across models.


:::highlight yellow 📌
Webhooks are only supported in the Unified API Schema. While the legacy version of the API remains fully functional, webhook capabilities are exclusive to the new unified API.
:::

Setting Up Webhooks

To use webhooks, include the webhook_config field in the request body when creating a task. Specify the endpoint and secret.

//POST https://api.piapi.ai/api/v1/task 
{
    "model": "suno/v3-chorip",
    "task_type": "lyrics",
    "input": {},
    "config": {
        "webhook_config": {
            "endpoint": "",
            "secret": ""
        }
    }
}

Field	Description	Details
endpoint	The URL where the webhook will be sent	Ensure that the receiving server is accessible by Cloudflare workers.
secret	Used to verify the request source	If a secret is provided, it will be included in the x-webhook-secret header.

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Receiving Webhooks

When will PiAPI send webhook notification

When a task is created or completed (i.e., when a task enters the completed or failed status), PiAPI sends an HTTP POST request to the specified URL.
Additionally, webhook notifications are also sent for certain tasks whenever there is a status update in the processing mode. These tasks include:

1. Music Generation tasks processed by Suno.
2. Tasks processed by Midjourney, created by users with the Creator Plan or higher.

Request body

The request body is in JSON format and includes two key fields: timestamp and data.

The timestamp helps in identifying duplicate notifications (such as in cases of retry), while the data field mirrors the response from the unified fetch API.

{
    "timestamp": 1723018391,
    "data": {}
}

Field	Description	Details
timestamp	Unix timestamp	Useful for detecting duplicate notifications.
data	Task data	Matches the structure from the unified fetch API.

The output field is critical in webhook notifications as it reflects the current result or progress of the task, with content varying depending on the model and task type.

:::highlight orange 🚀
Here is an example of a webhook request for a Luma video generation task:
:::

{
  "timestamp": 1724511853,
  "data": {
    "task_id": "58cb41b7-556d-46c0-b82e-1e116aa1a31a",
    "model": "luma",
    "task_type": "video_generation",
    "status": "completed",
    "config": {
      "webhook_config": {
        "endpoint": "https://webhook.site/xxxxx",
        "secret": "123456"
      }
    },
    "input": {
      "aspect_ratio": "16:9",
      "expand_prompt": true,
      "image_end_url": "https://i.imgur.com/CSmEZud.png",
      "image_url": "https://i.imgur.com/eJkSUnA.png",
      "loop": false,
      "user_prompt": ""
    },
    "output": {
      "generation": {
        "id": "ab9124ef-49d4-4da7-bf12-0c3891a3cca8",
        "prompt": "",
        "state": "completed",
        "created_at": "2024-08-24T15:01:52.727Z",
        "video": {
          "url": "https://storage.cdn-luma.com/dream_machine/49995d70-d0f3-4b0d-afb0-ec034107e4e2/watermarked_video08fe0802a4e104f1a80fb6c6c658710ee.mp4",
          "url_no_watermark": "https://img.midjourneyapi.xyz/ephemeral/db7420f9-8a24-48fd-ade5-ede803e835db.mp4",
          "width": 1168,
          "height": 864,
          "thumbnail": ""
        },
        "like": null,
        "estimate_wait_seconds": null
      }
    },
    "meta": {
      "created_at": "2024-08-24T23:01:12.3556324+08:00",
      "started_at": "2024-08-24T23:01:36.7432691+08:00",
      "ended_at": "2024-08-24T23:04:13.5301322+08:00",
      "usage": {
        "type": "luma_quota",
        "frozen": 30,
        "consume": 30
      }
    },
    "detail": {
      "account_id": 1,
      "is_using_private_pool": false
    },
    "logs": [],
    "error": {
      "code": 0,
      "message": ""
    }
  }
}

In webhook notifications, the output field within the data structure is particularly important as it represents the result (or latest progress) of the task. The content of the output field mirrors that of the output field in the response from the get task endpoint.

Handling Webhook Deliveries

Your endpoint must return a successful status code (2xx) quickly to avoid timeouts before performing any complex logic.

To handle webhook requests, create an HTTP or HTTPS endpoint that accepts POST requests with a JSON payload. For local development, you can use HTTP, but once publicly accessible, the endpoint must support HTTPS.

• The endpoint should handle POST requests with the event object in JSON format.
• Always respond with a 2xx status code before performing any extended logic.

Here's an example of a Next.js webhook handler:

// pages/api/piapi-webhook.js
export default async function handler(req, res) {
  console.log("🪝 incoming webhook!", req.body.data.taskid);
  const prediction = req.body;
  await saveToMyDatabase(prediction);
  await sendSlackNotification(prediction);
  res.end();
}

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Webhook Retries

If PiAPI does not receive a successful response (status 2xx), or if it encounters a 4xx or 5xx error, it will retry the webhook after 5 seconds. Up to 3 attempts will be made for each notification.

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Best Practices for Using Webhooks

1. Use HTTPS for Security: Ensure your server uses HTTPS to protect data in transit, preventing unauthorized access.
2. Timestamp Verification: The timestamp in webhook requests is crucial for:
   • Preventing Replay Attacks: Compare the request’s timestamp with the current system time. If the difference is too large, reject the request.
   • Deduplication: Use the timestamp to avoid processing the same event multiple times.
3. Testing Webhooks: We recommend services like webhook.site to test and debug webhook requests before moving to production.