apisix/doc/zh-cn/plugins/limit-req.md

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- [English](../../plugins/limit-req.md)
# limit-req
限制请求速度的插件,使用的是漏桶算法。
## 参数
|名称 |可选项 |描述|
|--------- |--------|-----------|
|rate |必选|指定的请求速率(以秒为单位),请求速率超过 `rate` 但没有超过 `rate` + `brust`)的请求会被加上延时。|
|burst |必选|请求速率超过 `rate` + `brust`)的请求会被直接拒绝。|
| key |必选|是用来做请求计数的依据,当前接受的 key 有:"remote_addr"(客户端IP地址), "server_addr"(服务端 IP 地址), 请求头中的"X-Forwarded-For" 或 "X-Real-IP"。|
|rejected_code |可选|当请求超过阈值被拒绝时,返回的 HTTP 状态码,默认 503。|
**key 是可以被用户自定义的,只需要修改插件的一行代码即可完成。并没有在插件中放开是处于安全的考虑。**
## 示例
### 开启插件
下面是一个示例,在指定的 route 上开启了 limit req 插件:
```shell
curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"methods": ["GET"],
"uri": "/index.html",
"plugins": {
"limit-req": {
"rate": 1,
"burst": 2,
"rejected_code": 503,
"key": "remote_addr"
}
},
"upstream": {
"type": "roundrobin",
"nodes": {
"39.97.63.215:80": 1
}
}
}'
```
你可以使用浏览器打开 dashboard`http://127.0.0.1:9080/apisix/dashboard/`,通过 web 界面来完成上面的操作,先增加一个 route
![添加路由](../../images/plugin/limit-req-1.png)
然后在 route 页面中添加 limit-req 插件:
![添加插件](../../images/plugin/limit-req-2.png)
### 测试插件
上述配置限制了每秒请求速率为 1大于 1 小于 3 的会被加上延时,速率超过 3 就会被拒绝:
```shell
curl -i http://127.0.0.1:9080/index.html
```
当你超过,就会收到包含 503 返回码的响应头:
```html
HTTP/1.1 503 Service Temporarily Unavailable
Content-Type: text/html
Content-Length: 194
Connection: keep-alive
Server: APISIX web server
<html>
<head><title>503 Service Temporarily Unavailable</title></head>
<body>
<center><h1>503 Service Temporarily Unavailable</h1></center>
<hr><center>openresty</center>
</body>
</html>
```
这就表示 limit req 插件生效了。
### 移除插件
当你想去掉 limit req 插件的时候,很简单,在插件的配置中把对应的 json 配置删除即可,无须重启服务,即刻生效:
```shell
curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"methods": ["GET"],
"uri": "/index.html",
"upstream": {
"type": "roundrobin",
"nodes": {
"39.97.63.215:80": 1
}
}
}'
```
现在就已经移除了 limit req 插件了。其他插件的开启和移除也是同样的方法。