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Nginx4-Nginx高可用Keepalived

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利用Keepalived实现Nginx高可用

Keepalived实现Nginx高可用

Keepalived的安装

下载keepalived官网:http://keepalived.org

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将keepalived解压到/usr/local/src目录下
tar -zxvf  keepalived-1.2.19.tar.gz -C /usr/local/src
 
进入到/usr/local/src/keepalived-1.2.19目录
cd /usr/local/src/keepalived-1.2.19
 
开始configure
./configure--prefix=/usr/local/keepalived
#编译并安装
make && make install
将keepalived添加到系统服务中
拷贝执行文件
cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
将init.d文件拷贝到etc下,加入开机启动项
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
将keepalived文件拷贝到etc下
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
创建keepalived文件夹
mkdir -p /etc/keepalived
将keepalived配置文件拷贝到etc下
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf
添加可执行权限
chmod +x/etc/init.d/keepalived
添加keepalived到开机启动
chkconfig --add keepalived
chkconfig keepalived on

Keepalived配置
keepalived相当于设置两台nginx主机抢占同一个ip，需要设置一个虚拟ip，这个虚拟ip代表客户端要访问的ip。
修改配置文件： /etc/keepalived/keepalived.conf

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#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

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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

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

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#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

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#!/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

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