Nginx 502 Bad Gateway

现象

请求页面得到502 Bad Gateway。

日志

查看error.log日志，发现有upstream sent too big header while reading response header from upstream日志。

2022/10/10 02:18:24 [error] 8333#8333: *28207118 upstream sent too big header while reading response header from upstream, client: 127.0.0.1, server: example.com, request: "GET /test", upstream: "http://example.com", host: "example.com", referrer: "http://test.com/"

原因

请求的Header过大，超出了Nginx代理的缓存区大小。

解决

扩大参数值：proxy_buffer_size、proxy_buffers、proxy_busy_buffers_size。

location / {
  proxy_pass       http://upstream;
  ...

  proxy_buffer_size          128k;
  proxy_buffers              4 256k;
  proxy_busy_buffers_size    256k;
}

Nginx 文档

http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffer_size