nginx header-connection

ref: https://datatracker.ietf.org/doc/html/rfc7230#section-6

The “Connection” header field allows the sender to indicate desired
control options for the current connection. In order to avoid
confusing downstream recipients, a proxy or gateway MUST remove or
replace any received connection options before forwarding the
message.

nginx转发,设置 Connection: close

proxy_set_header Connection "";

By default, NGINX redefines two header fields in proxied requests, “Host” and “Connection”, and eliminates the header fields whose values are empty strings. “Host” is set to the $proxy_host variable, and “Connection” is set to close.

而且 其中一个配置：

Syntax:    proxy_http_version 1.0 | 1.1;
Default:    proxy_http_version 1.0;
Context:    http, server, location
This directive appeared in version 1.1.4.

所以其实 nginx 到后端 例如 tomcat 之间的连接是 http1.0的协议

所以解决 方法很简单：

upstream http_backend {
    server 127.0.0.1:8080;
}

server {
    ...

    location /http/ {
        proxy_pass http://http_backend;
        proxy_http_version 1.1;
        proxy_set_header Connection "";
        ...
    }
}

参考文章

• nginx优化——包括https、keepalive等
• 解决nginx到后端服务器Connection: close问题
• Nginx 对 Connection 头的处理过程
• nginx http header [Connection: keep-alive]的实现原理
• nginx中开启keepalive后应答反而为close的原因