keepalived实现nginx高可用详解

keepalived介绍

Keepalived 是一个用于做双机热备（HA）的软件，它的主要功能是实现真实机的故障隔离及负载均衡器间的失败切换，提高系统的可用性。一个LVS服务会有2台服务器运行Keepalived，一台为主服务器（MASTER），一台为备份服务器（BACKUP），但是对外表现为一个虚拟IP，主服务器会发送特定的消息给备份服务器，当备份服务器收不到这个消息的时候，即主服务器宕机的时候， 备份服务器就会接管虚拟IP，继续提供服务，从而保证了高可用性。

两台机器分别安装keepalived

yum install keepalived -y

配置Keepalived

配置主服务器 keepalved.conf

cat /etc/keepalived/keepalived.conf
global_defs {router_id  nginx01
}
vrrp_script chk_nginx_proxy {      #<==定义vrrp脚本，检测HTTP端口。script "/etc/keepalived/check_nginx.sh"    #<==执行脚本，当nginx服务有问题，就停掉keepalived服务。interval 2    #<==间隔2秒。weight 2
}
vrrp_instance VI_1 {state MASTERinterface ens192virtual_router_id 51priority 150advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {100.100.137.250}track_script {    #触发检查chk_nginx_proxy}
}

配置备服务器 keepalved.conf

cat /etc/keepalived/keepalived.conf
global_defs {router_id nginx02
}
vrrp_script chk_nginx_proxy {      #<==定义vrrp脚本，检测HTTP端口。script "/etc/keepalived/check_nginx.sh"    #<==执行脚本，当nginx服务有问题，就停掉keepalived服务。interval 2    #<==间隔2秒。weight 2
}vrrp_instance VI_1 {state BACKUPinterface ens192virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {100.100.137.250}track_script {    #触发检查chk_nginx_proxy}
}

配置nginx脚本

分别在nginx01，nginx02上配置如下脚本

cat /etc/keepalived/check_nginx.sh
#!/bin/basha=$(systemctl is-active nginx)
if [  $a  != active ]
thensystemctl stop keepalived
fichmod 755 /etc/keepalived/check_nginx.sh

启动

# 两台都是先启动nginx
systemctl start nginx
systemctl enable nginx
systemctl status nginx# 之后再分别启动keepalived
systemctl start keepalived
systemctl enable keepalived
systemctl status keepalived

这时已经配置好了。测试是否高可用即可。