nginx的502,503,504

:-}

502 Bad Gateway
The server was acting as a gateway or proxy and received an invalid response from the upstream server.
503 Service Unavailable
The server is currently unavailable (because it is overloaded or down for maintenance). Generally, this is a temporary state.
504 Gateway Time-out
The server was acting as a gateway or proxy and did not receive a timely response from the upstream server.

502 Bad Gateway

fpm进程挂掉或者后端程序过长时间未返回。

503 Service Unavailable

当遇到这个状态码的时候表示服务临时不可用,比如nginx配置了频率限制而client端又超过了配置的限制后就会收到503的响应。

504 Gateway Time-out

nginx的fastcgi模块有一个fastcgi_read_timeout配置,它表示从FastCGI server获取数据的超时时间。