利用keepalived实现高可靠 动态管理 ngnix

实际工作中ngnix肯定要做成高可用模式，防止一个ngnix挂了，所有请求都无法访问成功，我们可以利用keepalived实现高可靠来动态管理ngnix,cong从而让ngnix也具备高可用性。

1 ，keepalived实现高可靠（HA）

HA(High Available), 高可用性集群，是保证业务连续性的有效解决方案，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，keepalive是一款可以实现高可靠的软件，通常部署在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。

2，keepalived安装

下载keepalived官网:http://keepalived.org

将keepalived解压到/usr/app目录下

tar -zxvf  keepalived-1.2.19.tar.gz -C /usr/app/

进入到/usr/app/keepalived-1.2.19目录

cd /usr/app/keepalived-1.2.19

开始configure

./configure --prefix=/usr/app/keepalived                             #指定keepalived的目录为 /usr/app/keepalived  

如果安装报错，是因为少一些依赖，执行如下命令安装依赖大全，，，

yum -y install gcc pcre-devel openssl openssl-devel

#编译并安装

make && make install

 

3，将keepalived添加到系统服务中

拷贝执行文件

cp /usr/app/keepalived/sbin/keepalived /usr/sbin/

将init.d文件拷贝到etc下,加入开机启动项

cp /usr/app/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived

将keepalived文件拷贝到etc下

cp /usr/app/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/app/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

 

4, 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

其实他的原理就是根据两台keepalived服务器绑定的共同的网段的ip地址（192.168.33.60），利用这个ip实现主备跳转切换，访问该ip默认等于访问主机的实际ip，当主机挂了，备机自动切换为主机，这是使用该ip访问依然成功，不过就相当于访问了备机ip。

5，配置keepalived心跳检查

要想实现ngnix主备自动切换，需要让用户自定义一个shell脚本并利用keepalived去检测用户自己的程序，返回状态给keepalived就可以了, 当脚本检测到 test1 服务器上的 ngnix挂了，那么keepalived会自动切换为test2服务器上的keepalived, 同时test1上的keepalived会根据自定义编写的脚本对test1上的ngnix进行重启或关闭等操作。

修改配置文件： /etc/keepalived/keepalived.conf

#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"
}

#BACKUP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
    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"
}

#添加切换通知脚本

vi /usr/app/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

#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

接下来自行测试即可，手动杀死ngnix进程，查看主备变化，自己看不解释了。