Nginx负载均衡器的优点:

实现看弹性化操作的架构，压力增大的时候可以临时添加后端Web服务器；

upstream具有负载均衡能力 (默认使用轮询) ，可以自动判断下面的机器，并且自动踢出不能正常提供服务的机器；

Keepalvied加Nginx监测脚本可保证单个nginx负载均衡器的有效性,避免单点故障

IP地址

nginx( 主LB ):192.168.1 5.132

nginx( 备LB ):192.168.15.133

VIP 地址 :192.168.15.135

Real 的 IP:192.168.1 5.128

Real 2 的 IP:192.168.1 5.130

部署整个环境用到的软件为 :

zlib-1.2.8.tar.gz

① 2 台 Web 主机（Ubuntu）上部署环境 ， 安装 Nginx+PHP-FPM+MySQL

② 分别在二台 Nginx 负载均衡器上安装 Nginx 及配置

安装GCC编译器等工具：

yum install -y gcc gcc-c++ autoconf automake libtool make openssl openssl-devel

安装 Nginx:

wget http://exim.mirror.fr/pcre/pcre-8.38.tar.gz

tar -zxvf pcre-8.38.tar.gz

cd pcre-8.38

./configure

make && make install

wget http://zlib.net/zlib-1.2.8.tar.gz

tar -zxvf zlib-1.2.8.tar.gz

cd zlib-1.2.8

./configure

make && make install

wget http://nginx.org/download/nginx-1.6.3.tar.gz

./configure --prefix=/usr/local/nginx

--sbin-path=/usr/local/nginx/sbin/nginx

--conf-path=/usr/local/nginx/conf/nginx.conf

--pid-path=/usr/local/nginx/logs/nginx.pid \

--with-http_ssl_module \

--with-http_stub_status_module \

--with-http_gzip_static_module \ 

make && make install 

注：查询"./configure --help"相关模块，按需求指定启用

Nginx.conf 配置文件 ， 二个 nginx 负载均衡器的文件一样

user  www-data www-data;  worker_processes  1;  error_log  /usr/local/nginx/logs/error.log notice;  pid        /usr/local/nginx/logs/nginx.pid;  worker_rlimit_nofile 51200;  events {      use epoll;      worker_connections  51200;  }  http {      include       mime.types;      default_type  application/octet-stream;      log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '                        '$status $body_bytes_sent "$http_referer" '                        '"$http_user_agent" "$http_x_forwarded_for"';      access_log  logs/access.log  main;      server_names_hash_bucket_size 128;      client_header_buffer_size 32k;      large_client_header_buffers 4 32k;      client_max_body_size 8m;      sendfile        on;      tcp_nopush     on;      server_tokens off;      keepalive_timeout  60;      fastcgi_connect_timeout 300;      fastcgi_send_timeout 300;      fastcgi_read_timeout 300;      fastcgi_buffer_size 64k;      fastcgi_buffers 4 64k;      fastcgi_busy_buffers_size 128k;      fastcgi_temp_file_write_size 128k;      gzip  on;      upstream backend      {      server 192.168.15.128;      server 192.168.15.130;      }      server {          listen       80;          server_name  192.168.15.135;          location / {              root   html;              index  index.php index.html index.htm;              proxy_redirect off;              proxy_set_header Host $host;              proxy_set_header X-Real-IP $remote_addr;              #后端的Web服务器可以通过X-Forwarded-For获取用户真实IP              proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;              proxy_pass http://backend;          }          error_page   500 502 503 504  /50x.html;          location = /50x.html {              root   html;          }                    location /nginx_status {              stub_status on;               auth_basic "NginxStatus";              auth_basic_user_file /usr/local/nginx/htpasswd;              #allow 127.0.0.1;              #deny all;          }          location ~* \.(ini|docx|txt|doc|pdf)$ {          #禁止访问文档性文件          root /usr/share/nginx/html;          deny all;          }          location ~ .*\.(gif|jpg|jpeg|png|bmp|swf|js|html|htm|css)$ {          root /home/image;          proxy_store on;          proxy_store_access user:rw group:rw all:rw;          proxy_temp_path /home/image;          if ( !-e $request_filename) {             proxy_pass  http://backend;          }      }  }  }

③ 在二台 Nginx 上安装及配置 keepali ved：

wget http://www.keepalived.org/software/keepalived-1.2.15.tar.gz

tar -zxvf keepalived-1.2.15.tar.gz

cd keepalived-1.2.15

./configure --sysconf=/etc/  --with-kernel-dir=/usr/src/kernels/2.6.32-573.8.1.el6.x86_64

make && make install

ln -s /usr/local/sbin/keepalived  /sbin/  

#这一步很重要，不执行ln -s会报错“Starting keepalived: /bin/bash: keepalived: command not found”

service keepalived start

二台 Nginx 上 keepalived.conf 配置文件如下 ， 配置完成后分别 service keepalived start 启动 ｡ 检验 keepalived配置 是否成功

主：

global_defs {     notification_email {       test@163.com     }     notification_email_from keepalived@localhost      smtp_server 127.0.0.1     smtp_connect_timeout 30     router_id LVS_MASTER  }  vrrp_script chk_http_port {  script "/usr/local/src/check_nginx_pid.sh"  interval 2                           #（检测脚本执行的间隔）  weight 2  }  vrrp_instance VI_1 {      state MASTER      interface bond0      virtual_router_id 51      priority 100      advert_int 1      authentication {          auth_type PASS          auth_pass 1111  }  track_script {  chk_http_port            #（调用检测脚本）  }      virtual_ipaddress {          192.168.15.135      }  }

备： 

global_defs {     notification_email {       test@163.com     }     notification_email_from keepalived@localhost      smtp_server 127.0.0.1     smtp_connect_timeout 30     router_id LVS_BACKUP  }  vrrp_script chk_http_port {  script "/usr/local/src/check_nginx_pid.sh"  interval 2                           #（检测脚本执行的间隔）  weight 2  }  vrrp_instance VI_1 {      state BACKUP      interface bond0      virtual_router_id 51      priority 66      advert_int 1      authentication {          auth_type PASS          auth_pass 1111  }  track_script {  chk_http_port            #（调用检测脚本）  }      virtual_ipaddress {          192.168.15.135      }  }

以下是针对nginx状态进行检测的脚本，第一次nginx服务死掉时，会重新启动，如果Nginx服务无法正常启动，则杀掉keepalived进程

vim  /usr/local/src/check_nginx_pid.sh

#!/bin/bash  A=`ps -C nginx --no-header |wc -l`          if [ $A -eq 0 ];then                                    /usr/local/nginx/sbin/nginx                if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then                  killall keepalived                            fi  fi

Ok，开始nginx 负载均衡测试， 停掉其中一台的任何服务， 不影响整个系统的运作 ｡

注：两台LBServer也可分别添加一个VIP①②（Keepalived心跳监控，服务不可用或者宕机，VIP①被备LBServer接管），外部使用智能DNS轮询两个VIP①②， 提高硬件资源利用率 。

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来自： http://my.oschina.net/HeAlvin/blog/552469?fromerr=YniWcE2v