Centos7 keepalived安装并监控mysql实现自动切换

安装

下载（https://www.keepalived.org/download.html）
wget https://www.keepalived.org/software/keepalived-2.1.5.tar.gz

tar -xvf keepalived-2.1.5.tar.gz -C /usr/local/src
cd /usr/local/src/keepalived-2.1.5
./configure --prefix=/
#安装一般不能一帆风顺，一般会缺少OpenSSL
#1.在线安装：yum install -y openssl openssl-devel
#2.离线安装：参考离线安装openssl.md

make && make install
修改配置 /etc/keepalived/keepalived.conf

#node117
! Configuration File for keepalived

global_defs {
	router_id lb01
}

vrrp_script chk_msql {
	script "/etc/keepalived/check_mysql.sh"
	interval 3
	timeout 9
	fall 2
	rise 2
	weight -20
}


vrrp_instance VI_1 {
	state BACKUP
	interface ens192
	virtual_router_id 125
	mcast_src_ip 192.168.6.117
	priority 100
	advert_int 1
	authentication {
		auth_type PASS
		auth_pass 1111
	}

	track_script {
		chk_msql
	}

	virtual_ipaddress {
		192.168.6.125
	}
}

#node118
! Configuration File for keepalived

global_defs {
	router_id lb01
}

vrrp_script chk_msql {
	script "/etc/keepalived/check_mysql.sh"
	interval 3
	timeout 9
	fall 2
	rise 2
	weight -20
}


vrrp_instance VI_1 {
	state BACKUP
	interface ens192
	virtual_router_id 125
	mcast_src_ip 192.168.6.118
	priority 100
	advert_int 1
	authentication {
		auth_type PASS
		auth_pass 1111
	}

	track_script {
		chk_msql
	}

	virtual_ipaddress {
		192.168.6.125
	}
}

#check_mysql.sh
#!/bin/bash
#MYSQL=mysql
#MYSQL_HOST=localhost
#MYSQL_USER=root
MYSQL_PASSWORD=xiaoWEI0923!


#$MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p$MYSQL_PASSWORD -e "show status;" >/dev/null 2>&1
mysql -uroot -p$MYSQL_PASSWORD -e "show status;" >/dev/null 2>&1
#$mysqlclient --host=$host --port=$port --user=$user --password=$password  -e "show databases;" > /dev/null 2>&1
if [ $? == 0 ]
then
    echo " $host mysql login successfully "
    exit 0
else
    #echo " $host mysql login faild"
    #/etc/init.d/keepalived stop
    exit 2
fi

#check_nginx.sh
#!/bin/bash
A=`ps -C nginx --no-header | wc -l`
if [ $A -eq 0 ];then 
    /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
    sleep 2
    if [ `ps -C nginx --no-header | wc -l` -eq 0 ];then
        #systemctl stop keepalived
        echo "nginx exit"
        exit 2
    fi
fi
echo "nginx running..."
exit 0

启动

systemctl enable keepalived.service
systemctl start keepalived.service

# 可通过status查看相关错误
systemctl status keepalived.service

测试

1.ip addr查看虚拟ip绑定到了哪台机器（假如为A机器）
2.停止A机器keepalived,确认ip绑定到了另一台机器（B机器）
3.启动A机器keealived，停止B机器上keepavlived，ip绑定到A机器
4.同样方式测试mysql，停止A机器mysql，ip绑定到了B
4.恢复A机器mysql，停止B机器mysql，ip绑定到了A
另一种配置方法

#通过端口区分不同业务

! Configuration File for keepalived
global_defs {
   router_id 001
}

vrrp_instance VI_1 {
    state MASTER
    interface ens192
    virtual_router_id 125
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.6.125
    }
    
    track_script { 
	nginx_check
    } 
}

vrrp_script nginx_check {
    script "/etc/keepalived/scripts/check_n.sh"
    interval 1
    weight -20
}

virtual_server 192.168.6.125 80 {
    delay_loop 6
    lb_algo rr 
    lb_kind DR
    persistence_timeout 50
    protocol TCP
    
    real_server 192.168.6.117 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
    real_server 192.168.6.118 80 {
        weight 1
        TCP_CHECK {
            connect_port 80
            connect_timeout 3
            nb_get_retry 3
            delay_before_retry 3
        }
    }
}