Keepalived+Nginx 高可用(主从模式)

1、下载
wget https://www.keepalived.org/software/keepalived-2.2.2.tar.gz

2、解压
tar -zxvf keepalived-2.2.2.tar.gz

3、安装依赖
yum -y install libnl libnl-devel  
否则，会报错编译会报错：*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.

4、编译安装
cd  keepalived-2.2.2
./configure --prefix=/usr/local/keepalived 
make && make install 

cp -raf /usr/local/keepalived/etc/keepalived/keepalived.conf /usr/local/keepalived/etc/keepalived/keepalived.conf_default
vim /usr/local/keepalived/etc/keepalived/keepalived.conf　

主节点192.168.115.148和从节点192.168.115.149存在差异，具体配置文件如下：

global_defs {               
   router_id Nginx_01
   script_user root
}
vrrp_script check_nginx {
        script "/usr/local/nginx/keepalived/check_nginx.sh"      #nginx检测脚本
        interval 2
    weight -5
    fall 3
    rise 2
}
vrrp_instance VI_1 {
    state MASTER
    interface ens192                         #指定HA监测网络的接口。与本机 IP 地址所在的网络接口相同，可通过ip addr 查看
    virtual_router_id 33                     #虚拟路由标识，这个标识是一个数字，同一个vrrp实例使用唯一的标识。即同一vrrp_instance下，MASTER和BACKUP必须是一致
    priority 100                             #定义优先级，数字越大，优先级越高，在同一个vrrp_instance下，MASTER的优先级必须大于BACKUP的优先级
    advert_int 1
    authentication {                         #设置验证类型和密码。主从必须一样
        auth_type PASS                       #设置vrrp验证类型，主要有PASS和AH两种
        auth_pass 1111                       #设置vrrp验证密码，在同一个vrrp_instance下，MASTER与BACKUP必须使用相同的密码才能正常通信
    }
    virtual_ipaddress {                      #VRRP HA 虚拟地址 如果有多个VIP，继续换行填写
     192.168.115.150
    }
    track_script {
        check_nginx
    }
}　

global_defs {               
   script_user root
   router_id Nginx_02
}
vrrp_script check_nginx {
    script "/usr/local/nginx/keepalived/check_nginx.sh"
    interval 2
    weight -5
    fall 3
    rise 2
}
vrrp_instance VI_1 {
    state BACKUP
    interface ens192
    virtual_router_id 33
    priority 50
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
      192.168.115.150
    }
    track_script {
        check_nginx
    }
}

vim /usr/local/nginx/keepalived/check_nginx.sh
chmod +x  /usr/local/nginx/keepalived/check_nginx.sh

#开机自启动
systemctl  enable keepalived

#查看状态
systemctl status keepalived

#启动
systemctl start keepalived

#加载配置
systemctl daemon-reload

#重启
systemctl restart keepalived

[Unit]
Description=LVS and VRRP High Availability Monitor
After=network-online.target syslog.target 
Wants=network-online.target 

[Service]
Type=forking
PIDFile=/run/keepalived.pid
KillMode=process
EnvironmentFile=-/usr/local/keepalived/etc/sysconfig/keepalived
#ExecStart=/usr/local/keepalived/sbin/keepalived  $KEEPALIVED_OPTIONS   ##注释默认
ExecStart=/usr/local/keepalived/sbin/keepalived -f /usr/local/keepalived/etc/keepalived/keepalived.conf ##指定配置文件
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target

#允许VRRP协议通过防火墙
firewall-cmd --add-rich-rule='rule protocol value="vrrp" accept' --permanent

#重新加载 firewalld 
firewall-cmd --reload