Nginx負載均衡+Keepalived高可用集羣

1、搭建環境及軟件版本

負載均衡：Nginx 高可用：Keepalived

Linux：Centos 6.5

Nginx：nginx-1.6.2

Keepalived：keepalived-1.2.13

LB-00：Nginx+Keepalived 192.168.174.40

LB-01：Nginx+Keepalived 192.168.174.41

Web1：LNMP 192.168.174.20

Web2：LAMP 192.168.174.30

2、負載均衡搭建

①解壓編譯安裝Nginx

yum install -y pcre-devel openssl openssl-devel
tar xf nginx-1.6.2.tar.gz 
cd nginx-1.6.2
./configure --prefix=/application/nginx-1.6.3 --user=nginx --group=nginx --with-http_ssl_module --with-http_stub_status_module
make && make install
ln -s /application/nginx-1.6.3/ /application/nginx
cd /application/nginx/conf/

②修改nginx配置文件

upstream bbs_server_pools 後端real-server地址池
在nginx.conf中用include包含 單獨的配置文件，單獨server標籤，

vim nginx.conf

worker_processes  1;
events {
    worker_connections  1024;
}
http {
log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';
upstream bbs_server_pools{
   server 192.168.174.20;
   server 192.168.174.30;
 }
    include       mime.types;
    #include extra/lb_www.conf;
    include extra/lb_bbs.conf;
    #include extra/lb_blog.conf;
}

cd extra/
touch lb_bbs.conf lb_www.conf lb_blog.conf
vim lb_bbs.conf 
vim lb_blog.conf 
vim lb_www.conf

server {
        listen       80;
        server_name  bbs.panda.org;
        location / {
                 proxy_pass http://bbs_server_pools;
                 proxy_set_header Host $host;
                 proxy_set_header X-Forwarded-For $remote_addr;
    }
}

③啓動服務

/application/nginx/sbin/nginx 

3、搭建高可用集羣

LB-00 爲主（master） LB-01 爲備（backup）

①yum安裝並配置keepalived

yum install keepalived -y
vim /etc/keepalived/keepalived.conf

authentication 認證方式兩邊要同樣

②啓動服務，實現VIP自動漂移

/etc/init.d/keepalived start

③開發守護進程腳本（以負載均衡 80端口爲例）

vim check_lb_nginx.sh

#!/bin/sh
while true
do
 if [ `netstat -lntup|grep nginx|wc -l` -ne 1 ];then
   /etc/init.d/keepalived stop
 fi
sleep 5
done

後臺運行守護腳本，中止主負載均衡的nginx，VIP當即切換

sh /home/scripts/check_lb_nginx.sh >/dev/null 2>&1 &