# Webhook 格式

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

如果你通过 webhook 订阅，收到的内容格式如下：

**添加或更新事件时：**

```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": ""
      }
    ]
  }
}
```

**添加或更新维护时：**

```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": ""
      }
    ]
  }
}
```

**组件更新时：**

```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": ""
  }
}
```

### 可能的状态页状态：

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

### 可能的组件状态：

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

### 可能的事件状态：

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

### 可能的维护状态：

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

## Webhook 负载校验

**强烈建议在 webhook 端点中校验负载。**

我们用一个密钥对 webhook 负载签名，并把签名放在名为 `x-instatus-webhook-signature` 的请求头中。这个签名让你可以验证该 webhook 确实来自 Instatus。

### 校验 Webhook 的步骤

1. 保存你在订阅 webhook 时生成的 **Webhook Secret**（在为某个页面订阅 webhook 时可以看到，也可以在那里自定义它）。

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

2. 在你的服务器上创建一个接收该 webhook 的新端点。

3. 把收到的签名与服务器生成的签名进行比较来校验。

4. 如果签名一致，就处理这个 webhook。

#### 代码示例

```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'))
```

### 为什么校验很重要

- **确保真实性**：保证该 webhook 确实来自我们的平台。
- **防止篡改**：能发现负载被改动过。
- **提升安全性**：防范重放攻击和未授权访问。