目标

• 现在只有两台服务器，都运行着nginx和mysql
• 当两台服务器都正常的时候
  • 用户访问nginx默认访问服务器A，如果A的nginx异常则访问B的nginx
  • 用户访问mysql默认访问服务器B，如果B的Mysql异常则访问A的Mysql
• 意思就是对这两台的服务器做两个VIP，实现两个进程的高可用

配置

• 如果大家对单个进程的高可用检测原理能够理解
• 那么对双进程也是很好理解的
• 可以理解为在同一个配置文件里配置两个单进程的高可用检测

配置效果图

• 关于配置的几点说明(在配置文件中都有)
  • 配置了两个虚拟路由组VI_NGINX和VI_MYSQL
  • 两个虚拟路由的vrid要不一样(这里一个配了51，一个配了52)
  • 服务器A的nginx初始权重为100，B为90
  • 服务器A的mysql初始权重为90，B为100
  • vip_nginx为192.168.1.200
  • vip_mysql为192.168.1.201
  • nginx和mysql的检测进程检测到异常时，会使得本机的权重下降20

服务器A

vrrp_script chk_nginx_process {
    script "/opt/context/keepalive_check/checkNginx.sh"
    interval 2            
    weight -20 
}

vrrp_instance VI_NGINX {
    state MASTER
    interface bond0
    virtual_router_id 51
    priority 100
    mcast_src_ip 192.168.1.100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 5678
    }
    virtual_ipaddress {
        192.168.1.200
    }

    track_script {
        chk_nginx_process
    }
}

vrrp_instance VI_MYSQL {
    state BACKUP
    interface bond0
    virtual_router_id 52
    priority 90
    mcast_src_ip 192.168.1.100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 15678
    }
    virtual_ipaddress {
        192.168.1.101
    }
}

服务器B

vrrp_script chk_mysql {
    script "/opt/context/keepalive_check/checkMysql.sh"
    interval 2
    weight -20
}

vrrp_instance VI_NGINX {
    state BACKUP
    interface bond0
    virtual_router_id 51
    priority 90
    mcast_src_ip 192.168.1.101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 5678
    }
    virtual_ipaddress {
        192.168.1.200
    }
}

vrrp_instance VI_MYSQL {
    state MASTER
    interface bond0
    virtual_router_id 52
    priority 100
    mcast_src_ip 192.168.1.101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 15678
    }
    virtual_ipaddress {
        192.168.1.201
    }

    track_script {
        chk_mysql
    }
}

检测脚本

• nginx

#!bin/bash

NginxProNum=`ps -C nginx --no-header | wc -l`
if [ $NginxProNum -eq 0 ];then
        #systemctl stop keepalived
        exit 1
fi
exit 0

• mysql

#!/bin/bash
MYSQL=/usr/local/mysql/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=rep
MYSQL_PASSWORD=pukkasoft
CHECK_TIME=3
  
#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
  
MYSQL_OK=1
  
function check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" >/dev/null 2>&1
    if [ $? = 0 ] ;then
    MYSQL_OK=1
    else
    MYSQL_OK=0
    fi
    return $MYSQL_OK
}
while [ $CHECK_TIME -ne 0 ]
do
    let "CHECK_TIME -= 1"
    check_mysql_helth
if [ $MYSQL_OK = 1 ] ; then
    CHECK_TIME=0
    exit 0
fi
if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 0 ]
then
    pkill keepalived
    exit 1
fi
sleep 1
done