keepalived

Posted 0221ljw

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1.1. 高可靠概念

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。

 

1.2. 高可靠软件keepalived

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。

1.3. keepalived安装

下载keepalived官网:http://keepalived.org

 

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

 

1.4. keepalived添加到系统服务中

拷贝执行文件

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

init.d文件拷贝到etc,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

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

创建keepalived文件夹

mkdir -p /etc/keepalived

keepalived配置文件拷贝到etc

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

 

##以上所有命令一次性执行:

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

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

cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

mkdir -p /etc/keepalived

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf

chmod +x /etc/init.d/keepalived

chkconfig --add keepalived

chkconfig keepalived on

 

添加keepalived到开机启动

chkconfig --add keepalived

chkconfig keepalived on

 

 

 

 

1.5. 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

    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nginxip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

 

1.6. 配置keepalived心跳检查

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

 

 

#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

#!/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

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"

}

 

#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

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