upstream and porxy_pass
-------------------------------------------------------------------
1.Simple reverse proxy
http:

upstream bbs_server{
    server 10.10.10.20;
    server 10.10.10.21;
    #check interval=3000 rise=2 fall=5 timeout=1000 type=http;
    }
server:
    location / {
        proxy_pass http://bbs_server;
        proxy_set_header Host     $host;
        proxy_set_header X-Forwarded-For $remote_addr;
    }
--------------------------------------------------------------------
2. Too based on domain names
--------------------------------------------------------------------
http:

upstream blog_server {
    #ip_hash;
    #server 10.10.10.20:8082 weight=5;
    #server 10.10.10.21:8082 weight=1;
    #check interval=3000 rise=2 fall=5 timeout=1000 type=http;
    server 10.10.10.20;
    server 10.10.10.21;
    }
upstream bbs_server {
    #ip_hash;
    #server 10.10.10.20:8081 weight=5;
    #server 10.10.10.21:8081 weight=1;
    server 10.10.10.20;
    server 10.10.10.21;
    }
upstream www_server {
    #ip_hash;
    #server 10.10.10.20:8080 weight=5;
    #server 10.10.10.21:8080 weight=1;
    server 10.10.10.20;
    server 10.10.10.21;
    }
---------------------------------------------------
server
    {
    listen     80;
    server_name www.linyaohong.com linyaohong.com ;
    location / {
        proxy_pass http://www_server;
        proxy_set_header Host     $host;
        proxy_set_header X-Forwarded-For $remote_addr;
        }
    }
server
    {
    listen     80;
    server_name bbs.linyaohong.com ;
    location / {
        proxy_pass http://bbs_server;
        proxy_set_header Host     $host;
        proxy_set_header X-Forwarded-For $remote_addr;
        }
    }
------------------------------------------------------------
3. nginx_proxy  Client agent  is iphone or  android
------------------------------------------------------------
http:

upstream static_server {
    server 10.10.10.21;
    }
upstream upload_server {
    server 10.10.10.20;
    } 
upstream default_server {
    server 10.10.10.21;
    }

server
{
    listen     80;
    server_name www.linyaohong.com linyaohong.com ;
    location / {
    if ($http_user_agent  ~*  "android")  
        {
        proxy_pass http://static_server;
        }
    if ($http_user_agent  ~*   "iphone") 
        {
        proxy_pass http://upload_server;
        }
    proxy_pass http://default_server;
    include proxy.conf;
    }
}
------------------------------------------------------------
4. nginx_proxy  URI 
------------------------------------------------------------
http:

upstream static_server {
    server 10.10.10.20;
	}
upstream upload_server {
    server 10.10.10.21;
	} 
upstream default_server {
    server 10.10.10.20;
	}
server
{
    listen     80;
    server_name www.linyaohong.com linyaohong.com ;
    location /static/
	{
        proxy_pass http://static_server;
    }
    location /upload/
	{
        proxy_pass http://upload_server;
    }
    location /
	{
        proxy_pass http://default_server;
    }
    include proxy.conf;
}
------------------------------------------------------------
5. nginx_proxy  User-agent
------------------------------------------------------------
http:

upstream static_server {
    server 10.10.10.21;
    }
upstream upload_server {
    server 10.10.10.20;
    } 
upstream default_server {
    server 10.10.10.20;
    }
server
{
    listen     80;
    server_name www.linyaohong.com linyaohong.com ;
    location / {
    if ($http_user_agent  ~*  "Trident")  
        {
        proxy_pass http://static_server;
        }	
    if ($http_user_agent  ~*   "Firefox") 
        {
        proxy_pass http://upload_server;
        }
    proxy_pass http://default_server;
    include proxy.conf;
    }
}
------------------------------------------------------------
5. proxy.conf
------------------------------------------------------------
proxy_set_header Host $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_connect_timeout 60;
proxy_send_timeout 60;
proxy_read_timeout 60;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;
------------------------------------------------------------
location / {
    proxy_pass http://127.0.0.1:1215;
    proxy_set_header HTTPS    "on";
    proxy_set_header Host     $host;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_connect_timeout 60;
    proxy_send_timeout 60;
    proxy_read_timeout 60;
    proxy_buffer_size 4k;
    proxy_buffers 4 32k;
    proxy_busy_buffers_size 64k;
    proxy_temp_file_write_size 64k;
}