Nginx反向代理負載均衡模塊功能詳述

1、ngx_http_upstream_module
http://nginx.org/en/docs/http/ngx_http_upstream_module.html#upstream

模塊常用功能說明：

1）定義後端集羣web節點信息，定義一個地址的池子
upstream oldboy {
    server 10.0.0.7:80;
    server 10.0.0.8:80;
    server 10.0.0.9:80;
}

2）實現權重值負載訪問功能
upstream oldboy {
    server 10.0.0.7:80 weight=3;
    server 10.0.0.8:80 weight=1;
    server 10.0.0.9:80 weight=1;
}

3）定義後端訪問的失敗次數-max_fails
upstream oldboy {
    server 10.0.0.7:80 weight=3 max_fails=3;
    server 10.0.0.8:80 weight=1 max_fails=3;
    server 10.0.0.9:80 weight=1 max_fails=3;
}

4）定義後端失敗重試的間隔-fail_timeout
upstream oldboy {
    server 10.0.0.7:80 weight=3 max_fails=3 fail_timeout=10s;
    server 10.0.0.8:80 weight=1 max_fails=3;
    server 10.0.0.9:80 weight=1 max_fails=3;
}
說明：在嘗試多次失敗後，在超時時間過去之後，會再給相應節點一次機會

5）定義後端服務的熱備節點-backup
upstream oldboy {
    server 10.0.0.7:80;
    server 10.0.0.8:80;
    server 10.0.0.9:80 backup;
}

模塊常用調度算法：

1）定義輪詢調度算法-rr-默認調度算法
   採取平均分配

2）定義權重調度算法-wrr
   能者多勞

3）定義靜態調度算法-ip_hash
說明：配置ip_hash時，一定不能和backup與weight參數同時出現
upstream oldboy {
    ip_hash;
    server 10.0.0.7:80;
    server 10.0.0.8:80;
    server 10.0.0.9:80 backup;
}

4）定義最小的連接數-least_conn
upstream oldboy {
    least_conn;
    server 10.0.0.7:80;
    server 10.0.0.8:80;
    server 10.0.0.9:80 backup;
}

2、ngx_http_proxy_module
http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass

模塊常用功能：

 proxy_set_header   --- 設置反向代理服務器到web服務器的HTTP請求報文中的頭部信息
說明：通過該配置，可以實現訪問負載均衡看到不同虛擬主機頁面信息 
server {
    listen       80;
    server_name  www.etiantian.org;
    root   html;
    index  index.html index.htm;
    location / {
    proxy_pass http://oldboy;
    proxy_set_header host $host;
   }
}
server {
    listen       80;
    server_name  bbs.etiantian.org;
    proxy_set_header host $host;
    root   html;
    index  index.html index.htm;
    location / {
    proxy_pass http://oldboy;
    proxy_set_header host $host;
   }
}

 說明：實現用戶訪問反向代理服務，讓web服務器日誌中記錄真實用戶IP地址信息 
server {
listen       80;
server_name  www.etiantian.org;
root   html;
index  index.html index.htm;
location / {
proxy_pass http://oldboy;
proxy_set_header host $host;
proxy_set_header X-Forwarded-For $remote_addr;
} 
}
server {
   listen       80;
   server_name  bbs.etiantian.org;
   root   html;
   index  index.html index.htm;
   location / {
   proxy_pass http://oldboy;
   proxy_set_header X-Forwarded-For $remote_addr;
  } 
}