随着Nginx在国内的发展潮流，越来越多的互联网公司都在使用Nginx，Nginx高性能、稳定性成为IT人士青睐的HTTP和反向代理服务器。Nginx负载均衡一般位于整个网站架构的最前端或者中间层，如果为最前端时单台Nginx会存在单点故障，也就是一台Nginx宕机，会影响用户对整个网站的访问。所以需要加入Nginx备份服务器，Nginx主服务器与备份服务器之间形成高可用，一旦发现Nginx主宕机，能快速将网站恢复至备份主机。Nginx+keepalived网络架构如图23-1所示：
Nginx+keepalived高性能WEB网络架构实战配置如下步骤：
1、环境准备
Nginx版本：nginx v1.12.0 Keepalived版本：keepalived v1.2.1 Nginx-1：192.168.0.138 （Master） Nginx-2：192.168.0.139 （Backup）
2、Nginx安装配置，Master、Backup服务器安装Nginx和keepalived
yum install -y pcre-devel
wget -c http://nginx.org/download/nginx-1.12.0.tar.gz tar -xzf nginx-1.12.0.tar.gz cd nginx-1.12.0 sed -i -e 's/1.12.0//g' -e 's/nginx//TDTWS/g' -e 's/"NGINX"/"TDTWS"/g' src/core/nginx.h ./configure --prefix=/usr/local/nginx --user=www --group=www --with-http_stub_status_module --with-http_ssl_module make make install
3、Keepalived安装配置
wget http://www.keepalived.org/software/keepalived-1.2.1.tar.gz
tar -xzvf keepalived-1.2.1.tar.gz cd keepalived-1.2.1 ./configure make && make install DIR=/usr/local/ cp $DIR/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/ cp $DIR/etc/sysconfig/keepalived /etc/sysconfig/ mkdir -p /etc/keepalived cp $DIR/sbin/keepalived /usr/sbin/ 注意：如果正常安装keepalive不能使用，可能是在configure时需要指定内核，例如./configure --with-kernel-dir=/usr/src/kernels/2.6.32-431.el6.x86_64/
使用yum安装keepalive
yum install -y keepalived*
4、配置Keepalived，master端keepalived.conf内容如下（包括两个vrrp实例）：
! Configuration File for keepalived global_defs { notification_email { support@jfedu.net } notification_email_from wgkgood@163.com smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_script chk_nginx { script "/data/sh/check_nginx.sh" interval 2 weight 2 } #VIP1 192.168.0.198 vrrp_instance VI_1 { state MASTER interface ens33 lvs_sync_daemon_inteface ens33 virtual_router_id 151 priority 100 advert_int 5 #nopreempt authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.0.198 } track_script { chk_nginx } } #VIP2 192.168.0.199 vrrp_instance VI_2 { state BACKUP interface ens33 lvs_sync_daemon_inteface ens33 virtual_router_id 152 priority 80 advert_int 5 #nopreempt authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.0.199 } track_script { chk_nginx } }
backup端的keepalived.conf内容如下：
! Configuration File for keepalived global_defs { notification_email { support@jfedu.net } notification_email_from wgkgood@163.com smtp_server 127.0.0.1 smtp_connect_timeout 30 router_id LVS_DEVEL } vrrp_script chk_nginx { script "/data/sh/check_nginx.sh" interval 2 weight 2 } #VIP1 192.168.0.198 vrrp_instance VI_1 { state BACKUP interface ens33 lvs_sync_daemon_inteface ens33 virtual_router_id 151 priority 80 advert_int 5 #nopreempt authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.0.198 } track_script { chk_nginx } } #VIP2 192.168.0.199 vrrp_instance VI_2 { state MASTER interface ens33 lvs_sync_daemon_inteface ens33 virtual_router_id 152 priority 100 advert_int 5 #nopreempt authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 192.168.0.199 } track_script { chk_nginx } }
5、如上配置还需要建立check_nginx脚本，用于检查本地Nginx是否存活，如果不存活，则kill keepalived实现切换。其中check_nginx.sh脚本内容如下：
#!/bin/bash #auto check nginx process NUM=`ps -ef|grep nginx|grep -vEc "check|grep"` if [ $NUM -eq 0 ];then service keepalived stop fi
6、通过查看日志/var/log/message，确认keepalived是否启动成功