基于keepalived的nginx高可用集群方案
基于keepalived的nginx高可用方案
Keepalived 是一种高性能的服务器高可用或热备解决方案,可以用来防止服务器单点故 障的发生,通过配Nginx可以实现web前端服务的高可用。
注:貌似阿里云的ECS服务器没法用keepalived(无法获取到VIP),遇到这种情况的建议还是用阿里云的SLB吧,简单省心。
相关文章:
范例项目: http://wosyingjun.iteye.com/blog/2312553
手把手教你认识并搭建Nginx:http://wosyingjun.iteye.com/blog/2252941
Nginx的基本配置与优化:http://wosyingjun.iteye.com/blog/2294512
一. 安装和配置nginx
见上述的相关文章。
二. 安装Keepalived(http://www.keepalived.org/download.html)
1、上传或下载 keepalived到 /usr/local/src 目录
2、解压安装
cd /usr/local/src tar -zxvf keepalived-1.2.18.tar.gz cd keepalived-1.2.18 ./configure --prefix=/usr/local/keepalived make && make install
3、将 keepalived 安装成 Linux 系统服务(因为没有使用 keepalived 的默认路径安装(默认是/usr/local),安装完成之后,需要做一些工作)
#复制默认配置文件到默认路径 mkdir /etc/keepalived cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/ #复制 keepalived 服务脚本到默认的地址 cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/ cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/ ln -s /usr/local/sbin/keepalived /usr/sbin/ ln -s /usr/local/keepalived/sbin/keepalived /sbin/
4、设置 keepalived 服务开机启动
chkconfig keepalived on
5、修改 Keepalived 配置文件
MASTER 节点配置文件(192.168.1.11) vi /etc/keepalived/keepalived.conf global_defs { ##keepalived自带的邮件提醒需要开启sendmail服务。建议用独立的监控或第三方SMTP ##标识本节点的字条串,通常为 hostname router_id 192.168.1.11 } ##keepalived会定时执行脚本并对脚本执行的结果进行分析,动态调整vrrp_instance 的优先级。如果脚本执行结果为0,并且weight配置的值大于0,则优先级相应的增加。 如果脚本执行结果非0,并且weight配置的值小于 0,则优先级相应的减少。其他情况, 维持原本配置的优先级,即配置文件中priority对应的值。 vrrp_script chk_nginx { script "/etc/keepalived/nginx_check.sh" ## 检测 nginx 状态的脚本路径 interval 2 ## 检测时间间隔 weight -20 ## 如果条件成立,权重-20 } ## 定义虚拟路由,VI_1为虚拟路由的标示符,自己定义名称 vrrp_instance VI_1 { state MASTER ## 主节点为MASTER,对应的备份节点为BACKUP interface eth1 ## 绑定虚拟IP的网络接口,与本机IP地址所在的网络接口相同 virtual_router_id 11 ## 虚拟路由的ID号,两个节点设置必须一样,建议用IP最后段 mcast_src_ip 192.168.1.11 ## 本机 IP 地址 priority 100 ## 节点优先级,值范围0-254,MASTER要比BACKUP高 nopreempt ## 优先级高的设置 nopreempt 解决异常恢复后再次抢占的问题 advert_int 1 ## 组播信息发送间隔,两个节点设置必须一样,默认 1s ## 设置验证信息,两个节点必须一致 authentication { auth_type PASS auth_pass 1111 } ## 将 track_script 块加入 instance 配置块 track_script { chk_nginx ## 执行 Nginx 监控的服务 } ## 虚拟 IP 池, 两个节点设置必须一样 virtual_ipaddress { 192.168.1.10 ## 虚拟 ip,可以定义多个 } } BACKUP 节点配置文件(192.168.1.12) vi /etc/keepalived/keepalived.conf global_defs { router_id 192.168.1.12 } vrrp_script chk_nginx { script "/etc/keepalived/nginx_check.sh" interval 2 weight -20 } vrrp_instance VI_1 { state BACKUP interface eth1 virtual_router_id 11 mcast_src_ip 192.168.1.12 priority 90 advert_int 1 authentication { auth_type PASS auth_pass 1111 } track_script { chk_nginx } virtual_ipaddress { 192.168.1.10 } }
6、编写 Nginx 状态检测脚本 /etc/keepalived/nginx_check.sh
脚本:如果nginx停止运行,尝试启动,如果无法启动则杀死本机的keepalived进程, keepalied将虚拟ip绑定到 BACKUP 机器上。内容如下: vi /etc/keepalived/nginx_check.sh !/bin/bash A=`ps -C nginx –no-header |wc -l` if [ $A -eq 0 ];then /usr/local/nginx/sbin/nginx sleep 2 if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then killall keepalived fi fi
7、给脚本赋执行权限
chmod +x /etc/keepalived/nginx_check.sh
8、启动 Keepalived
service keepalived start Starting keepalived: [ OK ]
9、Keepalived+Nginx的高可用测试
(1)关闭 192.168.1.11 中的 Nginx,Keepalived会将它重新启动 /usr/local/nginx/sbin/nginx -s stop (2)关闭 192.168.1.11 中的 Keepalived,VIP 会切换到 192.168.1.12 中 service keepalived stop (3)重新启动 192.168.1.11 中的 Keepalived,VIP 又会切回到 192.168.1.11 中来 service keepalived start
附Keepalived 服务管理命令:
停止:service keepalived stop
启动:service keepalived start
重启:service keepalived restart
查看状态:service keepalived status