keepalived实现redis双主备份

时间：2015-12-17 14:25:16 阅读：715 评论：0 收藏：0 [点我收藏+]

现在的生产环境基本上都采用主备方式，而如何实现redis的主备呢？一般情况下，redis实现主从复制比较简单，只需要在从服务器的配置文件里配置 "slaveof "即可。但这样存在一个问题：主服务器挂掉时，可临时将业务地址转移到从服务器，但从服务器无法进行写操作。为解决这个问题，在网上查找了一些资料。主要有以下几种方案

使用keepalived+监控脚本实现主备切换
使用rediscluster实现双主切换，原理就是模仿MySQL的bin-log机制。

本文介绍一下第一种方案

设计思路

当 Master 与 Slave 均运作正常时, Master负责服务，Slave负责Standby；
当 Master 挂掉，Slave 正常时, Slave接管服务，同时关闭主从复制功能；
当 Master 恢复正常，则从Slave同步数据，同步数据之后关闭主从复制功能，恢复Master身份，于此同时Slave等待Master同步数据完成之后，恢复Slave身份。
然后依次循环。

环境介绍

Master:192.168.3.185

Slave: 192.168.3.186

VIP: 192.168.3.188

实施步骤

1.两台主机上分别安装keepalived服务

#yum -y install keepalived

2.修改keepalived配置文件

Master

}

vrrp_script chk_redis {

    script "/etc/keepalived/scripts/redis_check.sh"
   interval 2
}

vrrp_instance VI_1 {
   state MASTER
   interface em1
   virtual_router_id 51
   priority 101
   authentication {
       auth_type PASS
       auth_pass redis
   }
   track_script {
       chk_redis
   }
   virtual_ipaddress {
       192.168.3.188
   }
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_backup.sh
notify_fault /etc/keepalived/scripts/redis_fault.sh
notify_stop   /etc/keepalived/scripts/redis_stop.sh
}

Slave

global_defs {
   notification_email {
     acassen@firewall.loc
     failover@firewall.loc
     sysadmin@firewall.loc
   }
   notification_email_from Alexandre.Cassen@firewall.loc
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id LVS_DEVEL
}

vrrp_script chk_redis {
   script "/etc/keepalived/scripts/redis_check.sh"
   interval 2
}

vrrp_instance VI_1 {
   state BACKUP
   interface em1
   virtual_router_id 51
#   mcast_src_ip 192.168.3.186
   priority 100
   authentication {
       auth_type PASS
       auth_pass redis
   }
   track_script {
       chk_redis
   }
   virtual_ipaddress {
       192.168.3.188
   }
notify_master    /etc/keepalived/scripts/redis_master.sh
notify_backup   /etc/keepalived/scripts/redis_backup.sh
notify_fault       /etc/keepalived/scripts/redis_fault.sh
notify_stop       /etc/keepalived/scripts/redis_stop.sh

}

3.编写脚本

首先在两台服务器分别创建监控redis的脚本

#!/bin/bash
netstat -ntlp |grep 6379
if [ "$?" == "0" ]; then
   echo $?
   exit 0
else
   echo $?
   exit 1
fi

然后是以下这些

notify_master    /etc/keepalived/scripts/redis_master.sh
notify_backup   /etc/keepalived/scripts/redis_backup.sh
notify_fault       /etc/keepalived/scripts/redis_fault.sh
notify_stop       /etc/keepalived/scripts/redis_stop.sh

当keepalived进入Master状态时，会执行notify_master;

当keepalived进入Backup状态时，会执行notify_backup;

当keepalived进入fault状态时，会执行notify_fault ；

当keepalived进入stop状态时，会执行notify_stop；

在主服务器上编写以下两个脚本

redis_master.sh

#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.3.186 6379 >> $LOGFILE 2>&1
sleep 10 #延迟10秒以后待数据同步完成后再取消同步状态
echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

redis_backup.sh

#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $LOGFILE
date >> $LOGFILE
echo "Being slave...." >> $LOGFILE 2>&1
sleep 15 # 延迟15秒待数据被对方同步完成之后再切换主从角色
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.3.186 6379 >> $LOGFILE 2>&1

在从服务器上编写以下两个脚本

#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE2>&1
echo "Run SLAVEOF cmd ..." >>$LOGFILE
$REDISCLI SLAVEOF 192.168.3.185 6379 >> $LOGFILE 2>&1
sleep 10 #延迟10秒以后待数据同步完成后再取消同步状态
echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

redis_backup.sh

#!/bin/bash
REDISCLI="/usr/local/redis/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $LOGFILE
date >> $LOGFILE
echo "Being slave...." >> $LOGFILE 2>&1
sleep 15 #延迟15秒待数据被对方同步完成之后再切换主从角色
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.3.185 6379 >> $LOGFILE 2>&1

主从共同编写以下两个脚本

redis_fault.sh

#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[fault]" >> $LOGFILE
date >> $LOGFILE

redis_stop.sh

#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[stop]">> $LOGFILE
date >> $LOGFILE

添加执行权限

#chmod +x *.sh

4.启动并验证

a.启动redis-server

b.启动keepalived

使用命令ip a查看VIP