Centos7 安装 Keepalived+Nginx 双机热备HA 的正确姿势 并开机自启 实践笔记

nginx_01 ip:192.168.59.128 主机
nginx_02 ip:192.168.59.129 从机
漂浮ip：192.168.59.130

systemctl stop firewalld.service #停止firewall
systemctl disable firewalld.service #禁止firewall开机启动
firewall-cmd --state #查看默认防火墙状态（关闭后显示notrunning，开启后显示running）

[root@localhost ~]# firewall-cmd --state
not running
[root@localhost ~]#

firewall-cmd --zone=public --add-port=80/tcp --permanent #添加放行端口(--permanent永久生效，没有此参数重启后失效)

```
firewall-cmd --zone=public --list-ports #查看防火墙放行端口列表

[root@localhost ~]# firewall-cmd --zone=public --add-port=18080/tcp --permanent #添加放行端口(--permanent永久生效，没有此参数重启后失效)
success
[root@localhost ~]# firewall-cmd --reload #刷新防火墙 使其生效
success
[root@localhost ~]# firewall-cmd --zone=public --list-ports #查看防火墙放行端口列表
80/tcp
[root@localhost ~]#

yum install keepalived
keepalived -v

cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak

vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
    router_id nginx_server_1
}
vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh"
    interval 2
    weight 20
    !weight为正数
    !如果脚本执行结果为0,,Master:weight+priority>Backup:weight+priority(不切换)
    !如果脚本执行结果不为0,Master:priority<Backup:priority+weight(切换)
    !weight为负数
    !如果脚本执行结果为0,,Master:priority>Backup:priority(不切换)
    !如果脚本执行结果不为0,Master:priority+weight<Backup:priority(切换)
    !一般来说,weight的绝对值要大于Master和Backup的priority之差
}
vrrp_instance VI_1 {
    state MASTER
    interface ens33 !网卡接口地址
    virtual_router_id 51
    mcast_src_ip 192.168.59.128 !nginx01 ip
    priority 100
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111 !认密码 两台nginx密码要一致
    }
    track_script {
        chk_nginx
    }
    virtual_ipaddress {
        192.168.59.222/24 !漂浮ip 可以有多个 回车隔开
    }
}

cp /etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf.bak

vi /etc/keepalived/keepalived.conf

state 和主不一样，是BACKUP
route_id 和主不一样
priority 小于主机

! Configuration File for keepalived
global_defs {
    router_id nginx_server_2
}
vrrp_script chk_nginx {
    script "/etc/keepalived/nginx_check.sh"
    interval 2
    weight 20
    !weight为正数
    !如果脚本执行结果为0,,Master:weight+priority>Backup:weight+priority(不切换)
    !如果脚本执行结果不为0,Master:priority<Backup:priority+weight(切换)
    !weight为负数
    !如果脚本执行结果为0,,Master:priority>Backup:priority(不切换)
    !如果脚本执行结果不为0,Master:priority+weight<Backup:priority(切换)
    !一般来说,weight的绝对值要大于Master和Backup的priority之差
}
vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 51
    mcast_src_ip 192.168.59.129
    priority 90
    nopreempt
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script {
        chk_nginx
    }
    virtual_ipaddress {
        192.168.59.222/24
    }
}

vim /etc/keepalived/nginx_check.sh

#!/bin/bash

A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];then
    /usr/sbin/nginx
    sleep 2
    if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
        killall keepalived
    fi
fi

chmod +xxx /etc/keepalived/nginx_check.sh

systemctl start keepalived //启动
systemctl enable keepalived //开机自启动