Nginx 负载均衡（主备）+Keepalived
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 :
nginx-1.6.3.tar.gz
prce-8.38.tar.gzzlib-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
tar -zxvf nginx-1.6.3.tar.gz
cd nginx-1.6.3/./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 。
</div>来自： http://my.oschina.net/HeAlvin/blog/552469?fromerr=YniWcE2v