NGINX学习笔记——传递请求头

原文地址：https://www.nginx.com/resources/admin-guide/reverse-proxy/
原文标题：Passing Request Headers

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默认情况，NGINX在代理请求时会重新定义两个HTTP头字段，“Host”和“Connection”，并删除值为空的头部字段。“Host”会被设置为 $proxy_host变量的值，“Connection”被设置为close。
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.

要改变这些设置，包括修改其他头字段，使用proxy_set_header指令。这个指令可以在location或者更高层使用。也可以在特定的server上下文或者在http块中，例如：
To change these setting, as well as modify other header fields, use the proxy_set_header directive. This directive can be specified in a location or higher. It can also be specified in a particular server context or in the http block. For example:

location /some/path/ {
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_pass http://localhost:8000;
}

在这个配置中，“Host”字段被设置为$host变量。
In this configuration the “Host” field is set to the $host variable.

要阻止一个头字段被传递给被代理的服务器，只要把它设置为空字符串。
To prevent a header field from being passed to the proxied server, set it to an empty string as follows:

location /some/path/ {
    proxy_set_header Accept-Encoding "";
    proxy_pass http://localhost:8000;
}