使用keepalived實現高可用

通常情況下，都是啟動2臺相同的業務系統，一台故障，另外一台自動接管。後端一般情況下我們使用集群，排除了單點故障造成的影響，前段7層負載的高可用就尤為重要了

keepalived使用vrrp協議，虛擬路由冗餘協議。依靠vmac和vip實現高可用技術方案，俗稱位址漂移。

搶占式高可用配置

1.實踐環境，配置實現虛ip轉移

狀態  ip  角色
節點1 10.0.0.5    master
節點2 10.0.0.6    backup
vip     10.0.0.3    
安裝keepalived
yum install keepalived -y
配置master的keepalived
global_defs 
vrrp_instance vi_1 
virtual_ipaddress } 
配置backup的keepalived
global_defs 
vrrp_instance vi_1 
virtual_ipaddress 
}#注意事項優先順序要設定的不一樣，vip位址是虛擬出來的，當然公網位址要真實存在
非搶占式區別
1、兩個節點的state都必須配置為backup
2、兩個節點在vrrp層加上配置 nopreempt
3、其中乙個節點的優先順序必須要高於另外乙個節點的優先順序。
兩台伺服器都角色狀態啟用nopreempt後，必須修改角色狀態統一為backup，唯一的區分就是優先順序。

2.修改keepalived配置檔案

[root@lb01 conf.d]# cat /etc/keepalived/keepalived.conf 
global_defs 
#定義指令碼存放的位置
vrrp_script check_web 
vrrp_instance vi_1 
virtual_ipaddress 
#呼叫並執行該指令碼
track_script 
}

#!/bin/bash

nginx_status=systemctl status nginx|awk  '/active/ '
if [ ! $nginx_status == "active" ];then
systemctl start nginx
sleep 3
nginx_status=systemctl status nginx|awk  '/active/ '
case $nginx_status in
active)
echo "start nginx succes,nginx is running"
;;inactive)
pkill keepalived
if [ $? -eq 0 ]; then
echo "nginx is down ,kill keepalived"
else
echo "keepalived cannot killed ,please go go"
fi;;
*)pkill keepalived
if [ $? -eq 0 ]; then
echo "nginx is down ,kill keepalived"
else
echo "keepalived cannot killed ,please go go"
fiesac
fi

#!/bin/bash

vip=10.0.0.3
master_ip=10.0.0.5
date=date +%f--%x
ip=ifconfig eth0|awk '/inet /'
echo "$date$hostname$_spiltbarin,do kill suessed" >/scripts/spilt.txt
while true;
do  
ping -c 2 -w 2 $master_ip &>/dev/null
result=$?
ip add|grep $vip &>/dev/null
if [ $result -eq 0 -a $? -eq 0  ];then
pkill keepalived &>/dev/null
echo "warining..spilt barin"
if [ $? -eq 0 ];then
mail -s " warning" "[email protected]" < /scripts/spilt.txt
else 
mail -s "spiltbrain ,please go go go" "[email protected]" < /scripts/spilt.txt
fi      
fi  
sleep 5
ping -c 2 -w 2 $vip &>/dev/null 
if [ ! $? -eq 0  ];then
systemctl start keepalived 
echo "$vip laqi"
fidone

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