> For the complete documentation index, see [llms.txt](https://www.axisnow.io/zh/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.axisnow.io/zh/docs/edge/policies/upstream-control.md).

# 回源控制

按规则改写回源地址与请求并控制连接缓冲和重试

回源控制插件决定边缘怎样把请求发往源站：发往哪个地址、用什么协议和 Host、URL 和请求头改成什么样，以及连接复用、缓冲和失败重试。域侧的回源配置是基线，本插件按规则对部分请求做改写和调优。

## 六个动作 <a href="#actions" id="actions"></a>

<table data-search="false"><thead><tr><th width="190">动作</th><th>作用</th><th width="150">默认规则</th></tr></thead><tbody><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#origin-rewrite">回源配置改写</a></td><td>改写源地址、协议、端口、Host 与 SNI</td><td>未配置</td></tr><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#url-rewrite">URL 改写</a></td><td>改写回源的路径和查询串，客户端地址和缓存 Key 不变</td><td>未配置</td></tr><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#header-rewrite">回源请求 Header 改写</a></td><td>添加、设置或删除回源请求头</td><td>未配置</td></tr><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#buffer">缓冲区设置</a></td><td>请求体是否收完再回源，源响应是否在边缘缓冲</td><td>都开启</td></tr><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#retry">回源重试</a></td><td>回源失败时重试的触发条件和次数</td><td>网络错误和 502 Bad Gateway、503 Service Unavailable、504 Gateway Timeout，最多 10 次</td></tr><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md#connection">连接复用与超时</a></td><td>源连接池与连接、读取、发送超时</td><td>连接池 30，超时 10 / 3600 / 3600 秒</td></tr></tbody></table>

它是[多动作配置类插件](/zh/docs/edge/policies/rules.md#rulesets)：每个动作各取序号最小的命中规则，一条规则可以只配其中几个动作。内置一条不可退订的默认规则排在最后，条件为**任意**，配了缓冲区、重试和连接三个动作；三个改写动作只在需要时添加规则。TCP 转发端点只有回源重试生效。

## 边界 <a href="#boundaries" id="boundaries"></a>

<table data-search="false"><thead><tr><th width="260">功能</th><th>配置位置</th></tr></thead><tbody><tr><td>域的源地址、回源协议、端口、Host，按路径或按端口回源</td><td><a href="/zh/docs/edge/endpoints/domains.md#origin-configuration">端点 › 域 › 回源配置</a>，本插件的改写覆盖它</td></tr><tr><td>一组源地址及其负载均衡</td><td><a href="/zh/docs/edge/endpoints/origin-address.md">端点 › 源地址</a>，回源配置改写可以直接引用</td></tr><tr><td>让客户端跳转到新地址</td><td><a href="/zh/docs/edge/policies/request-processing.md#redirect">请求处理 › URL 重定向</a></td></tr><tr><td>回源时传递真实客户端 IP</td><td><a href="/zh/docs/edge/policies/real-ip.md#forward">真实客户端 IP › 转发</a></td></tr><tr><td>回源 TLS 证书校验与客户端证书</td><td><a href="/zh/docs/edge/policies/ssl-tls/configuration.md#origin-tls-verify">SSL/TLS › 源证书校验</a></td></tr></tbody></table>

## 最佳实践 <a href="#best-practices" id="best-practices"></a>

* **流式接口和大文件上传按路径关闭缓冲**：SSE、大模型对话等逐段输出的接口关闭源响应缓冲区，否则客户端整段一次收到或超时；大文件上传的路径关闭请求体缓冲区，否则上传要等边缘收完才回源。各用一条只覆盖这些路径的规则，关闭响应缓冲的请求不写入缓存。
* **不能重复提交的接口禁用重试**：支付、下单等接口默认已不重试非幂等请求，但 GET 形式的扣减类接口不在其中，按路径加一条禁用重试的规则。
* **按 worker 数估算源站连接**：连接池大小是每个 worker 的值，源站看到的空闲连接约为该值乘以边缘的 worker 数再乘以边缘数，源站的连接上限要按此设置。
* **改写源地址时核对 Host**：回源配置改写不改变回源 Host，新源站按 Host 分发时要在同一条规则里显式填写。

## 下一步 <a href="#next-steps" id="next-steps"></a>

<table data-search="false"><thead><tr><th width="160">页面</th><th>内容</th></tr></thead><tbody><tr><td><a href="/zh/docs/edge/policies/upstream-control/configuration.md">配置项</a></td><td>六个动作的取值、默认值与注意事项</td></tr></tbody></table>


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