# Webhook 格式

Source: https://instatus.com/help/zh-tw/webhooks

如果你透過 webhook 訂閱，會收到以下格式的內容：

**新增或更新事件時：**

```json
{
  "meta": {
    "unsubscribe": "",
    "documentation": ""
  },
  "page": {
    "id": "",
    "status_indicator": "",
    "status_description": "",
    "url": ""
  },
  "incident": {
    "backfilled": false,
    "created_at": "",
    "impact": "",
    "name": "",
    "resolved_at": "",
    "status": "",
    "updated_at": "",
    "id": "",
    "url": "",
    "incident_updates": [
      {
        "id": "",
        "incident_id": "",
        "body": "",
        "status": "",
        "created_at": "",
        "updated_at": ""
      }
    ]
  }
}
```

**新增或更新維護時：**

```json
{
  "meta": {
    "unsubscribe": "",
    "documentation": ""
  },
  "page": {
    "id": "",
    "status_indicator": "",
    "status_description": "",
    "url": ""
  },
  "maintenance": {
    "backfilled": false,
    "created_at": "",
    "impact": "",
    "name": "",
    "resolved_at": "",
    "status": "",
    "updated_at": "",
    "id": "",
    "url": "",
    "duration": "",
    "maintenance_updates": [
      {
        "id": "",
        "maintenance_id": "",
        "body": "",
        "status": "",
        "created_at": "",
        "updated_at": ""
      }
    ]
  }
}
```

**更新元件時：**

```json
{
  "meta": {
    "unsubscribe": "https://<status-page-domain>/unsubscribe?id=${subscriber.id}&token=${subscriber.unsubscribeToken}",
    "documentation": ""
  },
  "page": {
    "id": "",
    "status_indicator": "",
    "status_description": "",
    "url": ""
  },
  "component_update": {
    "created_at": "",
    "new_status": "",
    "component_id": ""
  },
  "component": {
    "created_at": "",
    "id": "",
    "name": "",
    "status": ""
  }
}
```

### 可能的狀態頁狀態：

- `UP`
- `HASISSUES`
- `UNDERMAINTENANCE`

### 可能的元件狀態：

- `OPERATIONAL`
- `UNDERMAINTENANCE`
- `DEGRADEDPERFORMANCE`
- `PARTIALOUTAGE`
- `MAJOROUTAGE`

### 可能的事件狀態：

- `INVESTIGATING`
- `IDENTIFIED`
- `MONITORING`
- `RESOLVED`

### 可能的維護狀態：

- `NOTSTARTEDYET`
- `INPROGRESS`
- `COMPLETED`

## Webhook 內容驗證

**強烈建議在 webhook 端點驗證 webhook 內容。**

我們會用一組密鑰對 webhook 內容簽章，並把簽章放在名為 `x-instatus-webhook-signature` 的標頭中。這個簽章讓你可以確認 webhook 確實來自 Instatus。

### 驗證 Webhook 的步驟

1. 保存你在訂閱 webhook 時產生的 **Webhook 密鑰**（在為某個頁面設定 webhook 訂閱時可以找到，你也可以在那裡自訂它）。

![Webhook 密鑰](https://instatus.com/help/notification/webhook-subscribe-example.png)

2. 在你的伺服器上建立一個新端點來接收 webhook。

3. 把簽章與你伺服器產生的簽章比對來驗證。

4. 如果兩個簽章相符，就處理這個 webhook。

#### 程式碼範例

```javascript
import crypto from 'crypto'
import express from 'express'

const app = express()
app.use(express.json())

const WEBHOOK_SECRET = 'your-webhook-secret'

function isVerifiedPayload(payload, signature, secret) {
  const hmac = crypto.createHmac('sha256', secret)
  const digest = hmac.update(JSON.stringify(payload)).digest('hex')
  return crypto.timingSafeEqual(Buffer.from(digest), Buffer.from(signature))
}

app.post('/endpoint/to/webhook', (req, res) => {
  const payload = req.body
  const signature = req.header('x-instatus-webhook-signature')

  if (!signature) {
    return res.status(400).send('Signature missing')
  }

  if (!isVerifiedPayload(payload, signature, WEBHOOK_SECRET)) {
    return res.status(401).send('Invalid signature')
  }

  // Process the valid webhook
  res.status(200).send('Webhook received')
})

app.listen(3000, () => console.log('Server running on port 3000'))
```

### 為什麼驗證很重要

- **確保真實性**：保證 webhook 確實來自我們的平台。
- **防止竄改**：偵測內容是否被修改。
- **提升安全性**：防範重放攻擊與未經授權的存取。