Nginx中的proxy_pass怎么使用

语法: proxy_pass URL;
场景: location, if in location, limit_except
说明: 设置后端代理服务器的•协议(protocol)和地址(address),以及location中可以匹配的一个可选的URI。协议可以是"http"或"https"。地址可以是一个域名或ip地址和端口，或者一个 unix-domain socket 路径。  
详见官方文档: http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_passURI的匹配，本文第四部分•重点讨论。

语法: proxy_pass address;
场景: server
说明: 设置后端代理服务器的地址。这个地址(address)可以是一个域名或ip地址和端口，或者一个 unix-domain socket路径。  
详见官方文档: http://nginx.org/en/docs/stream/ngx_stream_proxy_module.html#proxy_pass

server {
   listen 127.0.0.1:12345;
   proxy_pass 127.0.0.1:8080;
}

server {
   listen 12345;
   proxy_connect_timeout 1s;
   proxy_timeout 1m;
   proxy_pass example.com:12345;
}

server {
   listen 53 udp;
   proxy_responses 1;
   proxy_timeout 20s;
   proxy_pass dns.example.com:53;
}

server {
   listen [::1]:12345;
   proxy_pass unix:/tmp/stream.socket;
}

server {
   listen      80;
   server_name www.test.com;

   # 正常代理，不修改后端url的   location /some/path/ {
       proxy_pass http://127.0.0.1;
   }

   # 修改后端url地址的代理（本例后端地址中，最后带了一个斜线)   location /testb {
       proxy_pass http://www.other.com:8801/;
   }

   # 使用 if in location   location /google {
       if ( $geoip_country_code ~ (RU|CN) ) {
           proxy_pass http://www.google.hk;
       }
   }

   location /yongfu/ {
       # 没有匹配 limit_except 的，代理到 unix:/tmp/backend.socket:/uri/       proxy_pass http://unix:/tmp/backend.socket:/uri/;;

       # 匹配到请求方法为: PUT or DELETE, 代理到9080       limit_except PUT DELETE {
           proxy_pass http://127.0.0.1:9080;
       }
   }

}

server {
   listen      80;
   server_name www.test.com;

   # 情形A   # 访问 http://www.test.com/testa/aaaa   # 后端的request_uri为: /testa/aaaa   location ^~ /testa/ {
       proxy_pass http://127.0.0.1:8801;
   }
   
   # 情形B   # 访问 http://www.test.com/testb/bbbb   # 后端的request_uri为: /bbbb   location ^~ /testb/ {
       proxy_pass http://127.0.0.1:8801/;
   }

   # 情形C   # 下面这段location是正确的   location ~ /testc {
       proxy_pass http://127.0.0.1:8801;
   }

   # 情形D   # 下面这段location是错误的   #   # nginx -t 时，会报如下错误:   #   # nginx: [emerg] "proxy_pass" cannot have URI part in location given by regular   # expression, or inside named location, or inside "if" statement, or inside   # "limit_except" block in /opt/app/nginx/conf/vhost/test.conf:17   #   # 当location为正则表达式时，proxy_pass 不能包含URI部分。本例中包含了"/"   location ~ /testd {
       proxy_pass http://127.0.0.1:8801/;   # 记住，location为正则表达式时，不能这样写！！！   }

   # 情形E   # 访问 http://www.test.com/ccc/bbbb   # 后端的request_uri为: /aaa/ccc/bbbb   location /ccc/ {
       proxy_pass http://127.0.0.1:8801/aaa$request_uri;
   }

   # 情形F   # 访问 http://www.test.com/namea/ddd   # 后端的request_uri为: /yongfu?namea=ddd   location /namea/ {
       rewrite    /namea/([^/]+) /yongfu?namea=$1 break;
       proxy_pass http://127.0.0.1:8801;
   }

   # 情形G   # 访问 http://www.test.com/nameb/eee   # 后端的request_uri为: /yongfu?nameb=eee   location /nameb/ {
       rewrite    /nameb/([^/]+) /yongfu?nameb=$1 break;
       proxy_pass http://127.0.0.1:8801/;
   }

   access_log /data/logs/www/www.test.com.log;
}

server {
   listen      8801;
   server_name www.test.com;
   
   root        /data/www/test;
   index       index.php index.html;

   rewrite ^(.*)$ /test.php?u=$1 last;

   location ~ \.php$ {
       try_files $uri =404;
       fastcgi_pass unix:/tmp/php-cgi.sock;
       fastcgi_index index.php;
       include fastcgi.conf;
   }

   access_log /data/logs/www/www.test.com.8801.log;
}

echo '$_SERVER[REQUEST_URI]:' . $_SERVER['REQUEST_URI'];