在架构分布式时常常使用nginx去做负载均衡,当其他服务挂掉的时候nginx可以把请求转向其它活着的服务。保证服务的稳定。可是如果nginx挂了呢?那岂不是糟了?这时候我们就需要keepalived来帮我们实现高可靠。
一般有两个或两个以上的节点,且分为活动节点及备用节点。部署在2台服务器上,分为一主一备。Keepalived可以对本机上的进程进行检测,一旦Master检测出某个进程出现问题,将自己切换成Backup状态,然后通知另外一个节点切换成Master状态。(不停的查进程,然后抢ip)
1.配置keepalived虚拟IP
修改配置文件: /etc/keepalived/keepalived.conf
#MASTER节点
global_defs {
}
vrrp_instance VI_1 {
state MASTER #指定A节点为主节点 备用节点上设置为BACKUP即可
interface eth0 #绑定虚拟IP的网络接口
virtual_router_id 51 #VRRP组名,两个节点的设置必须一样,以指明各个节点属于同一VRRP组
priority 100 #主节点的优先级(1-254之间),备用节点必须比主节点优先级低
advert_int 1 #组播信息发送间隔,两个节点设置必须一样
authentication { #设置验证信息,两个节点必须一致
auth_type PASS
auth_pass 1111
}
virtual_ipaddress { #指定虚拟IP, 两个节点设置必须一样
192.168.33.60/24 #如果两个nginx的ip分别是192.168.33.61,,...62,则此处的虚拟ip跟它俩同一个网段即可
}
}
#BACKUP节点
global_defs {
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 51
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.33.60/24
}
}
分别启动两台机器上的keepalived
service keepalived start
测试:
杀掉master上的keepalived进程,你会发现,在slave机器上的eth0网卡多了一个ip地址
查看ip地址的命令: ip addr
2.配置keepalived心跳检查
原理:
Keepalived并不跟nginx耦合,它俩完全不是一家人
但是keepalived提供一个机制:让用户自定义一个shell脚本去检测用户自己的程序,返回状态给keepalived就可以了
#MASTER节点
global_defs {
}
vrrp_script chk_health {
script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"
interval 1 #每隔1秒执行上述的脚本,去检查用户的程序ngnix
weight -2
}
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 1
priority 100
advert_int 2
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_health
}
virtual_ipaddress {
10.0.0.10/24
}
notify_master "/usr/local/keepalived/sbin/notify.sh master"
notify_backup "/usr/local/keepalived/sbin/notify.sh backup"
notify_fault "/usr/local/keepalived/sbin/notify.sh fault"
}
#添加切换通知脚本
vi /usr/local/keepalived/sbin/notify.sh
#!/bin/bash
case "$1" in
master)
/usr/local/nginx/sbin/nginx
exit 0
;;
backup)
/usr/local/nginx/sbin/nginx -s stop
/usr/local/nginx/sbin/nginx
exit 0
;;
fault)
/usr/local/nginx/sbin/nginx -s stop
exit 0
;;
*)
echo 'Usage: notify.sh {master|backup|fault}'
exit 1
;;
esac
#添加执行权限
chmod +x /usr/local/keepalived/sbin/notify.sh
global_defs {
}
vrrp_script chk_health {
script "[[ `ps -ef | grep nginx | grep -v grep | wc -l` -ge 2 ]] && exit 0 || exit 1"
interval 1
weight -2
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 1
priority 99
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_health
}
virtual_ipaddress {
10.0.0.10/24
}
notify_master "/usr/local/keepalived/sbin/notify.sh master"
notify_backup "/usr/local/keepalived/sbin/notify.sh backup"
notify_fault "/usr/local/keepalived/sbin/notify.sh fault"
}
#在第二台机器上添加notify.sh脚本
#分别在两台机器上启动keepalived
service keepalived start
chkconfig keepalived on
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