Keepalived+Nginx主备切换实现高可用

 Keepalived+Nginx主备切换实现高可用
Keepalived： 
基于VRRP（虚拟路由器冗余协议）来实现对web服务的高可用方案
 
安装keepalived
0.  下载安装包，解压tar -zxvf xx，进入目录
1.  ./configure --prefix=/data/program/keepalived --sysconf=/etc
2. 缺少依赖opensssl .  yum install openssl-devel
3. 建立软链接 ln -s /data/program/keepalived/sbin/keepalived /sbin
4.  ln -s /data/program/keepalived/sbin/keepalived /sbin
5. cp /data/program/keepalived-1.3.4/keepalived/etc/init.d/keepalived /etc/init.d/
6. 添加系统服务：chkconfig  --add keepalived / chkconfig keepalived on
7. 服务开关 service keepalived start|stop..
 
 
keepalived日志文件配置
在/etc/rsyslog.conf里添加:local0.*  /var/log/keepalived.log
重新启动keepalived和rsyslog服务：
   service rsyslog restart
service keepalived restart
tail -f  /var/log/keepalived.log  查看日志
 
keepalived+nginx实现双机热备
开发一个虚拟ip:192.168.130.100
配置两台nginx：ip192.168.130.130、131
 
修改Keepalived配置文件
vi /etc/keepalived/keepalived.conf

Master(主)  Keepalived配置文件

Backup(备)  Keepalived配置文件

vrrp_script check {         script "/data/program/nginx/sbin/nginx_service.sh"         interval 2         weight -9 } global_defs {    router_id LVS_DEVEL } vrrp_instance VI_1 {     state MASTER     interface ens33     virtual_router_id 51     priority 60     advert_int 1     authentication {         auth_type PASS         auth_pass 2222     }     virtual_ipaddress {          192.168.232.100     }     track_script {         check     } } virtual_server 192.168.232.100 80 {     delay_loop 5     lb_algo rr     lb_kind NAT     persistence_timeout 51 protocol TCP     real_server 192.168.232.133 80 {         weight 1         TCP_CHECK {             connect_timeout 2             nb_get_retry 2             delay_before_retry 2             connect_port 80         }}}

vrrp_script check {         script "/data/program/nginx/sbin/nginx_service.sh"         interval 2         weight -9 } global_defs {    router_id LVS_DEVEL } vrrp_instance VI_1 {     state BACKUP     interface ens33     virtual_router_id 51     priority 40     advert_int 1     authentication {         auth_type PASS         auth_pass 2222     }     virtual_ipaddress {          192.168.232.100     }     track_script {         check     } } virtual_server 192.168.232.100 80 {     delay_loop 5     lb_algo rr     lb_kind NAT     persistence_timeout 51     protocol TCP     real_server 192.168.232.132 80 {         weight 1         TCP_CHECK {             connect_timeout 2             nb_get_retry 2             delay_before_retry 2             connect_port 80         }}}

 
配置文件说明
1. vrrp_instance配置：state指定初始状态（主、备）。interface 为网卡名字。virtual_router_id                                相同的为一个组。Priority为节点优先级，主的要大于备的。advert int 检查间隔，默认 1秒。auth type为认证方式。track_script 引用脚本。
2. virtual_server配置：delay_loop健康检查间隔。lb_algo 调度算法。 lb_kind负载均衡规则。 会话保持时间。Protocol使用的协议。
3. real_server配置：Weight 默认为1,0为失效。connect_timeout连接超时时间。nb_get_retry 重连次数。delay_before_retry 重连间隔时间。connect_port健康检查的端口的端口。
4. vrrp_script配置：interval脚本执行间隔。weight脚本优先级。script 脚本路径。
5.Nginx_service.sh判断nginx是否宕机，若宕机，结束Keepalived服务。
给脚本权限 chmod +x  /data/program/nginx/sbin/nginx_service.sh
脚本内容：
#!/bin/sh
nginxPidNum=`ps-C nginx --no-header |wc -l`
keepalivedPidNum=`ps-C keepalived --no-header |wc -l`
if [$nginxPidNum -eq 0 ];then
    killall keepalived
elif [$keepalivedPidNum -eq 0 ];then
    service keepalived start
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