参考文档：
http://blog.jobbole.com/100390/
http://lanlian.blog.51cto.com/6790106/1303195

环境：主库：192.168.6.119
备库：192.168.6.121
vip： 192.168.6.120

1 master与slave端都安装keepalive

[root@MYSQL src]# wget http://www.keepalived.org/software/keepalived-1.2.12.tar.gz
[root@MYSQL src]# tar -xf keepalived-1.2.12.tar.gz
[root@MYSQL src]# cd keepalived-1.2.12
[root@MYSQL src]# yum -y install gcc gcc-c++ gcc-g77 ncurses-devel bison libaio-devel cmake libnl* libpopt* popt-static openssl-devel
[root@MYSQL keepalived-1.2.12]# ./configure
[root@MYSQL keepalived-1.2.12]# make && make install
[root@MYSQL src]#mkdir /etc/keepalived/
[root@MYSQL src]# cp /usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
[root@MYSQL src]# cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
[root@MYSQL src]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[root@MYSQL src]#cp /usr/local/sbin/keepalived /usr/sbin/

2. 配置 keepalived

[root@MYSQL keepalived]# vi keepalived.conf

! Configuration File for keepalived

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL ##配置是为了标识当前节点，两个节点的此项设置可相同，也可不相同

}

vrrp_script chk_http_port { ---配合脚本使用，比如说检查nginx是否存活，检查mysql是否存活等
script "/usr/local/keepalived/nginx.sh" #在这里添加脚本链接
interval 3 #脚本执行间隔
weight -2 #脚本结果导致的优先级变更  ###如果检测返回值不为真weight -2 表示减2，权重值降低，backup server权重值（99）>现Master（100-2）的，切换
}

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

    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

###nopreempt   ###这个参数也可以防止切换到从库后，主keepalived恢复后自动切换回主库

         advert_int 1

    authentication {     #设置验证信息，两个节点必须一致

        auth_type PASS

        auth_pass 1111

    }

track_script {
chk_http_port #添加脚本执行
}

virtual_ipaddress {

192.168.6.120 =====vip，指定一个或多个vip

    }

}

上面的脚本简单的查看http进程是否存在，不存在就退出返回假。

点击(此处)折叠或打开

#!/bin/bash
A=`netstat -nputl|grep -i 80 |wc -l`
if [ $A -eq 0 ];then
exit 1;
#/etc/init.d/keepalived stop
fi

实验一：
master与backup ip分别如下
[root@node1 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:7a:c6:9c brd ff:ff:ff:ff:ff:ff
inet 192.168.6.114/24 brd 192.168.6.255 scope global eth0
inet 192.168.6.120/32 scope global eth0
inet6 fe80::a00:27ff:fe7a:c69c/64 scope link
valid_lft forever preferred_lft forever
[root@node2 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:03:1b:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.6.115/24 brd 192.168.6.255 scope global eth0
inet6 fe80::a00:27ff:fe03:1ba1/64 scope link
valid_lft forever preferred_lft forever
关闭主库http
[root@node1 keepalived]# /etc/init.d/httpd stop
Stopping httpd: [ OK ]
主库与从库ip：
[root@node1 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:7a:c6:9c brd ff:ff:ff:ff:ff:ff
inet 192.168.6.114/24 brd 192.168.6.255 scope global eth0
inet6 fe80::a00:27ff:fe7a:c69c/64 scope link
valid_lft forever preferred_lft forever
[root@node2 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:03:1b:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.6.115/24 brd 192.168.6.255 scope global eth0
inet 192.168.6.120/32 scope global eth0 ---vip飘到从库了
inet6 fe80::a00:27ff:fe03:1ba1/64 scope link
valid_lft forever preferred_lft forever
恢复主库http
[root@node1 keepalived]# /etc/init.d/httpd start
Starting httpd: [ OK ]
主库与从库ip：
[root@node1 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:7a:c6:9c brd ff:ff:ff:ff:ff:ff
inet 192.168.6.114/24 brd 192.168.6.255 scope global eth0
inet 192.168.6.120/32 scope global eth0 ---vip又飘回主库了
inet6 fe80::a00:27ff:fe7a:c69c/64 scope link
valid_lft forever preferred_lft forever
[root@node2 keepalived]# ip a
2: eth0: mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 08:00:27:03:1b:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.6.115/24 brd 192.168.6.255 scope global eth0
inet6 fe80::a00:27ff:fe03:1ba1/64 scope link
valid_lft forever preferred_lft forever

nopreempt 参数的作用：静止vip再飘回来（少用，根据情况配置）

node1	node2	vip漂移过程（关闭主库http，恢复主库http）	原因
无nopreempt	无nopreempt	node1》node2》node1
nopreempt	无nopreempt	node1》node2》node2（vip不飘了）	node1静止vip飘回去
无nopreempt	nopreempt	一直在node1上，飘不动	node2静止vip飘过去
nopreempt	nopreempt	一直在nide1上，漂不动	node2静止vip飘过去

实验二：

配置文件为
1. [root@node1 keepalived]# more keepalived.conf
  ! Configuration File for keepalived
  
  global_defs {
  notification_email {
  acassen@firewall.loc
  failover@firewall.loc
  sysadmin@firewall.loc
  }
  notification_email_from Alexandre.Cassen@firewall.loc
  smtp_server 192.168.200.1
  smtp_connect_timeout 30
  router_id LVS_DEVEL
  }
  
  vrrp_script chk_http_port {
  script "/usr/local/keepalived/nginx.sh"
  }
  
  vrrp_instance VI_1 {
  state MASTER
  interface eth0
  virtual_router_id 51
  priority 99
  advert_int 1
  authentication {
  auth_type PASS
  auth_pass 1111
  }
  
  track_script {
  chk_http_port
  }
  virtual_ipaddress {
  192.168.6.120
  }
  }
脚本改为：若http服务失效，则kill keepalive进程
1. #!/bin/bash
  A=`netstat -nputl|grep -i 80 |wc -l`
  if [ $A -eq 0 ];then
  #exit 1;
  /etc/init.d/keepalived stop
  fi
和实验一的效果一样：vip先飘到从库，恢复http后，启动keepalive后又飘回主库，要想不飘回主库，改小权重

实验一二的区别：一个是通过权重来控制vip的飘逸。一个直接是控制keepalive进程的存活来控制vip的飘逸

3.如何在状态转换时进行通知？

1.要在状态转换是进行通知，需要定义通知脚本可以在

vrrp_sync_group{

}中定义，也可以在

vrrp_instance{

｝中定义

通过man keepalived命令可以查看通知脚本定义的两种方法

第一种

# to MASTER transition

notify_master /path/to_master.sh

# to BACKUP transition

notify_backup /path/to_backup.sh

# FAULT transition

notify_fault "/path/fault.sh VG_1"

第二种

#arguments

# $1 ="GROUP"|"INSTANCE"

# $2 = name of group or instance

# $3 = target state of transition

# ("MASTER"|"BACKUP"|"FAULT")

notify /path/notify.sh
下面用一个脚本notify.sh实现状态转换通知的简单示例：

#!/bin/bash

#Author: MageEdu <linuxedu@foxmail.com>

#description: An example of notify script

#

vip=192.168.6.120

contact='root@localhost'

notify(){

    mailsubject="`hostname` to be $1: $vip floating"

    mailbody="`date '+%F %H:%M:%S'`: vrrptransition, `hostname` changed to be $1"

    echo $mailbody | mail -s"$mailsubject" $contact

}

case "$1" in

    master)

        notify master

        exit 0

    ;;

    backup)

        notify backup

        exit 0

    ;;

    fault)

        notify fault

        exit 0

    ;;

    *)

        echo 'Usage: `basename $0`{master|backup|fault}'

        exit 1

    ;;

esac

chmod +x notify.sh

主从配置文件修改

[root@node1 keepalived]# more keepalived.conf

! Configuration File for keepalived

global_defs {

   notification_email {

     acassen@firewall.loc

     failover@firewall.loc

     sysadmin@firewall.loc

   }

   notification_email_from Alexandre.Cassen@firewall.loc

   smtp_server 192.168.200.1

   smtp_connect_timeout 30

   router_id LVS_DEVEL

}

vrrp_script chk_http_port {

   script "/usr/local/keepalived/nginx.sh"

   interval 3

   weight -2

}

vrrp_instance VI_1 {

    state MASTER

    interface eth0

    virtual_router_id 51

    priority 99

# nopreempt

         advert_int 1

    authentication {

        auth_type PASS

        auth_pass 1111

    }

track_script {

        chk_http_port

    }



   notify_master "/usr/local/keepalived/notify.sh master"

   notify_backup"/usr/local/keepalived/notify.sh backup"

   notify_fault"/usr/local/keepalived/notify.sh fault"

virtual_ipaddress {

192.168.6.120

    }

}

测试：

关闭主库http服务

[root@node1 ~]# /etc/init.d/httpd stop

Stopping httpd: [ OK ]

[root@node1 ~]# mail

Mail version 8.1 6/6/93. Type ? for help.

"/var/spool/mail/root": 1 message 1 new

>N 1 root@localhost.local Thu Jun 30 21:10 16/716 "node1 to be backup:"

[root@node2 keepalived]# mail
Mail version 8.1 6/6/93. Type ? for help.
"/var/spool/mail/root": 1 message 1 new
>N 1 root@localhost.local Thu Jun 30 21:10 16/716 "node2 to be master:"

恢复主库http服务

[root@node1 ~]# mail
Mail version 8.1 6/6/93. Type ? for help.
"/var/spool/mail/root": 2 messages 1 new 2 unread
U 1 root@localhost.local Thu Jun 30 21:10 17/726 "node1 to be backup:"
>N 2 root@localhost.local Thu Jun 30 21:12 16/716 "node1 to be master:"

[root@node2 keepalived]# mail
Mail version 8.1 6/6/93. Type ? for help.
"/var/spool/mail/root": 2 messages 1 new 2 unread
U 1 root@localhost.local Thu Jun 30 21:10 17/726 "node2 to be master:"
>N 2 root@localhost.local Thu Jun 30 21:12 16/716 "node2 to be backup:"

参考文档
http://kaifly.blog.51cto.com/3209616/1665729 --MySQL主库高可用 -- 双主单活故障自动切换方案
http://www.tuicool.com/articles/nYvuYf ---结合keepalived实现redis群集高可用故障自动切换

ITPub博客

【Mysql】keepalive的安装与配置

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