Redis+keepalived 主从搭建
设计思路：redis 主和 redis从正常同步；
redis主keepalived 启动，执行redis_master.sh脚本，vip在自己身上；
redis 从keepalived 启动，执行redis_slave.sh脚本；
redis主服务关闭，则redis主执行redis_fault.sh脚本， vip落在ipredis 从上，redis从执行redis_master.sh脚本，变成主；
redis主服务开启，则redis主执行redis_slave.sh脚本变成从，vip还在redis 从上，还是主；
redis从服务关闭，则redis从执行redis_fault.sh脚本， vip落在redis主上，redis主执行redis_master.sh脚本，变成主；
redis从服务开启，则redis从执行redis_slave.sh脚本变成从， vip还在redis主上，redis主继续做主，此时为redis初试主从状态；
环境：
192.168.1.39 redis
192.168.1.52 redis-slave
192.168.1.75 vip
一:安装keepalived
(redis和redis-slave两台服务器都安装)
yum -y install ipvsadm keepalived
二:安装redis
(redis和redis-slave两台服务器都安装)
tar -zxvf redis-2.4.17.tar.gz
cd redis-2.4.17
./configure
make
make install
redis-slve只需注意一点
# vim /etc/redis.conf
slaveof 192.168.1.39 6379
三：通过Keepalived实现Redis Failover自动故障切换
修改Master和Slave的/etc/hosts文件
# cat /etc/hosts
192.168.1.39 redis
192.168.1.52 redis-slave
Master上是
# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=redis
Slave上是
# cat /etc/sysconfig/network
NETWORKING=yes
HOSTNAME=redis-slave
修改完主机名重启机器生效
默认安装完成keepalived之后是没有配置文件的，因此我们需要手动创建：
首先，在Master上创建如下配置文件：
# vim /etc/keepalived/keepalived.conf
global_defs {
notification_email {
liyongshan213@sina.com
}
notification_email_from keepalived@redis
router_id redis
}
vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"
interval 1
}
vrrp_instance mes_Redis {
state MASTER
interface eth0
garp_master_delay 10
smtp_alert
virtual_router_id 3
priority 100
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.75
}
track_script {
chk_redis
}
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_slave.sh
notify_fault/etc/keepalived/scripts/redis_fault.sh
notify_stop /etc/keepalived/scripts/redis_stop.sh
}
然后，在Slave上创建如下配置文件：
# vim /etc/keepalived/keepalived.conf
global_defs {
notification_email {
liyongshan213@sina.com
}
notification_email_from keepalived@redis-slave
router_id redis-salve
}
vrrp_script chk_redis {
script "/etc/keepalived/scripts/redis_check.sh"
interval 1
}
vrrp_instance mes_Redis {
state BACKUP
interface eth0
garp_master_delay 10
smtp_alert
virtual_router_id 3
priority 90
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.1.237
}
track_script {
chk_redis
}
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_slave.sh
notify_fault/etc/keepalived/scripts/redis_fault.sh
notify_stop /etc/keepalived/scripts/redis_stop.sh
}
在Master和Slave上创建监控Redis的脚本
mkdir /etc/keepalived/scripts
vim /etc/keepalived/scripts/redis_check.sh
#!/bin/bash
ALIVE=`/usr/local/bin/redis-cli PING`
if [ "$ALIVE" == "PONG" ]; then
echo $ALIVE
exit 0
else
echo $ALIVE
exit 1
fi
编写以下负责运作的关键脚本：
notify_master /etc/keepalived/scripts/redis_master.sh
notify_backup /etc/keepalived/scripts/redis_slave.sh
notify_fault /etc/keepalived/scripts/redis_fault.sh
notify_stop /etc/keepalived/scripts/redis_stop.sh
因为Keepalived在转换状态时会依照状态来呼叫：
当进入Master状态时会呼叫notify_master
当进入Backup状态时会呼叫notify_backup
当发现异常情况时进入Fault状态呼叫notify_fault
当Keepalived程序终止时则呼叫notify_stop
首先，在Redis Master上创建notity_master与notify_backup脚本：
vim /etc/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.1.236 6379 >> $LOGFILE2>&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
vim /etc/keepalived/scripts/redis_slave.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $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 192.168.1.236 6379 >> $LOGFILE2>&1
接着，在Redis Slave上创建notity_master与notify_backup脚本：
vim /etc/keepalived/scripts/redis_master.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.1.235 6379 >> $LOGFILE2>&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
vim /etc/keepalived/scripts/redis_slave.sh
#!/bin/bash
REDISCLI="/usr/local/bin/redis-cli"
LOGFILE="/var/log/keepalived-redis-state.log"
echo "" >> $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 192.168.1.235 6379 >> $LOGFILE2>&1
然后在Master与Slave创建如下相同的脚本：
vim /etc/keepalived/scripts/redis_fault.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "" >> $LOGFILE
date >> $LOGFILE
vim /etc/keepalived/scripts/redis_stop.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "" >> $LOGFILE
date >> $LOGFILE
在Master与Slave给脚本都加上可执行权限：
chmod +x /etc/keepalived/scripts/*.sh
脚本创建完成以后，我们开始按照如下流程进行测试：
1.启动Master上的Redis
# /usr/local/bin/redis-server /etc/redis.conf
2.启动Slave上的Redis
# /usr/local/bin/redis-server /etc/redis.conf
3.启动Master上的Keepalived
/etc/init.d/keepalived start
4.启动Slave上的Keepalived
/etc/init.d/keepalived start
5.尝试通过VIP连接Redis:
# /usr/local/bin/redis-cli -h 192.168.1.75 info
role:master
slave0:192.168.1.52,6379,online
连接成功，Slave也连接上来了
6.尝试插入一些数据：
# /usr/local/bin/redis-cli -h 192.168.1.75 SET Hello Redis
从VIP读取数据
# /usr/local/bin/redis-cli -h 192.168.1.75 GET Hello
"Redis"
从Master读取数据
# /usr/local/bin/redis-cli -h 192.168.1.39 GET Hello
"Redis"
从Slave读取数据
# /usr/local/bin/redis-cli -h 192.168.1.52 GET Hello
"Redis"
下面，模拟故障产生：
将Master上的Redis进程杀死：
# /usr/local/bin/redis-cli shutdown
查看Master上的Keepalived日志
# tail /var/log/keepalived-redis-state.log
Thu Sep 27 08:29:01 CST 2012
同时Slave上的日志显示：
# tail /var/log/keepalived-redis-state.log
Thu Nov 15 12:06:04 CST 2012
Being master....
Run SLAVEOF cmd ...
OK
Run SLAVEOF NO ONE cmd ...
OK
然后我们可以发现，Slave已经接管服务，并且担任Master的角色了。
./redis-cli -h 192.168.1.75 info
./redis-cli -h 192.168.1.52 info
role:master
然后我们恢复Master的Redis进程
主变成slave
然后把52redis停掉
39恢复主的角色，在把52redis开启
恢复39是主，52是备
自动切换成功！
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