keepalived+nginx遇到的几个问题

nginx masterIP 192.168.119.120
nginx backupIP 192.168.119.121
VIP 192.168.119.130

MASTER

! Configuration File for keepalived

global_defs {                               
        router_id LVS1                      
}
vrrp_script chk_nginx {
    script "/etc/keepalived/chk_nginx.sh"
    interval 3
    weight -20
    fall 3
}
vrrp_instance VI_1 {     
    state MASTER         
    interface ens33      
    virtual_router_id 51 
    priority 100         
    advert_int 1         
    authentication {     
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {  
        192.168.119.130
    }
    track_script {
        chk_nginx
    }
}

---

BACKUP

! Configuration File for keepalived

global_defs {                             
        router_id LVS2                 
}

vrrp_script chk_nginx {
    script "/etc/keepalived/chk_nginx.sh"
    interval 3
    weight -20
    fall 3
}
vrrp_instance VI_1 {    
    state BACKUP         
    interface ens33      
    virtual_router_id 51 
    priority 90          
    advert_int 1         
    authentication {     
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {  
        192.168.119.130
    }
    track_script {
        chk_nginx
    }
}

---

chk_nginx.sh

#!/bin/bash                                                                                                                                              
#
COUNT1=`ss -anpt | grep nginx | wc -l `
if [ $COUNT1 -eq 0 ] ; then
    /usr/local/sbin/nginx -s start
    sleep 2
        COUNT2=`ss -anpt | grep nginx | wc -l`
        if [ $COUNT2 -eq 0 ] ; then
            /usr/bin/kill -15 `cat /var/run/keepalived.pid`
            echo -e "keeplived is stoped"
        else
            exit 0
        fi  
fi

---

tail -50f /var/log/messages
遇到一个问题 /etc/keepalived/chk_nginx.sh exited due to signal 15
起初的chk_nginx.sh脚本

#!/bin/bash -x
#
COUNT1=`ss -anpt | grep nginx | wc -l `
if [ $COUNT1 -eq 0 ] ; then
    /usr/local/sbin/nginx -s stop
    sleep 1
    /usr/local/sbin/nginx -s start
    sleep 2
        COUNT2=`ss -anpt | grep nginx | wc -l`
        if [ $COUNT2 -eq 0 ] ; then
            /usr/bin/kill -15 `cat /var/run/keepalived.pid`
            echo -e "keeplived is stoped"
        else
            exit 0
        fi  
fi

将上面配置文件中vrrp_script interval的值要修改成小于chk_nginx.sh中sleep的值（3），我直接把stop给删掉了
另外chk_nginx.sh sleep的值不宜过大最好不要超过3，否则也会出现exited due to signal 15问题，偶尔会出time out问题
备注：
    vrrp_script
    告诉 keepalived 在什么情况下切换，所以尤为重要。可以有多个 vrrp_script
    script ： 自己写的检测脚本。也可以是一行命令如killall -0 nginx
    interval 2 ： 每2s检测一次
    weight -5 ： 检测失败（脚本返回非0）则优先级 -5
    fall 2 ： 检测连续 2 次失败才算确定是真失败。会用weight减少优先级（1-255之间）
    rise 1 ： 检测 1 次成功就算成功。但不修改优先级
这里要提示一下script一般有2种写法：
1.通过脚本执行的返回结果，改变优先级，keepalived继续发送通告消息，backup比较优先级再决定
2.脚本里面检测到异常，直接关闭keepalived进程，backup机器接收不到advertisement会抢占IP