redis+keepalived高可用方案

目的：实现redis的高可用

原理：redis主从复制+keepalived

一：环境介绍

Master：192.168.10.52

Slave ：192.168.10.53

VIP ：192.168.10.100

redis端口： 6378

二：设计思路

1.当master和slave均正常工作时，master负责服务，Slave负责Standby;

2.当master挂掉，Slave正常时，Slave接管服务并升级至master，关闭主从复制，进行读写；

3.当原master恢复正常时，降级为slave，开启主从复制。

三：安装服务

1.安装redis

bash> wget http://download.redis.io/releases/redis-3.2.8.tar.gz

bash> tar zxf redis-3.2.8.tar.gz

bash> cd redis-3.2.8

bash> make && make PREFIX=/usr/local/redis install

bash> ln -s /usr/local/redis/bin/* /usr/local/bin/

bash> mkdir /etc/redis

bash> cp redis.conf /etc/redis/redis.conf

bash> sed -i 's/daemonize no/daemonize yes/g' /etc/redis/redis.conf #已守护进程方式运行

bash> vim /etc/init.d/redis

#!/bin/bash

. /etc/rc.d/init.d/functions

exec=/usr/local/bin/redis-server

prog=redis

pidfile="/var/run/redis_6379.pid"

lockfile=/var/lock/subsys/$prog

args=" /etc/redis/redis.conf"

start() {

[ -x $exec ] || exit 5

[ -f $config ] || exit 6

echo -n $"Starting $prog: "

daemon --pidfile=${pidfile} $exec $args

retval=$?

echo

if [ $retval -eq 0 ]; then

touch $lockfile || retval=4

return $retval

}

stop() {

echo -n $"Stopping $prog: "

killproc -p ${pidfile} $prog

retval=$?

echo

[ $retval -eq 0 ] && rm -f $lockfile

return $retval

}

restart() {

stop

start

}

reload() {

restart

}

force_reload() {

restart

}

rh_status() {

# run checks to determine if the service is running or use generic status

status -p ${pidfile} $prog

}

rh_status_q() {

rh_status >/dev/null 2>&1

}

case "$1" in

start)

rh_status_q && exit 0

;;

stop)

rh_status_q || exit 0

;;

restart)

;;

reload)

rh_status_q || exit 7

;;

force-reload)

force_reload

;;

status)

rh_status

;;

condrestart|try-restart)

rh_status_q || exit 0

restart

;;

echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload}"

exit 2

esac

exit $?

#以上为redis启动脚本

bash> chmod +x /etc/init.d/redis

bash> /etc/init.d/redis start

#至此redis安装完毕

2.安装Keepalived

bash> yum install openssl-devel kernel-devel -y

bash> wget http://www.keepalived.org/software/keepalived-1.3.5.tar.gz

bash> tar zxf keepalived-1.3.5.tar.gz

bash> cd keepalived-1.3.5

bash> ./configure --with-kernel-dir=/usr/src/kernels/2.6.32-358.2.1.el6.x86_64/ --prefix=/usr/local/keepalived

bash> make && make install

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

bash> cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/

bash> mkdir /etc/keepalived

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

bash> ln -s /usr/local/keepalived/sbin/* /usr/sbin/

bash> ln -s /usr/local/keepalived/bin/* /usr/sbin/

#至此keepalived安装完毕

四：修改配置文件和相关脚本

1.在master上创建配置文件

bash> vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

vrrp_script chk_redis {

script "/etc/keepalived/scripts/redis_check.sh" ###监控脚本

interval 2 ###监控时间

}

#网卡需要注意，使用ifconfig查看一下当前活动网卡

vrrp_instance VI_1 {

state BACKUP ###设置为BACKUP

interface eth1 ###监控网卡

virtual_router_id 51

priority 100 ###权重值

nopreempt ###不抢占VIP

authentication {

auth_type PASS ###加密

auth_pass 1111 ###密码

}

track_script {

chk_redis ###执行上面定义的chk_redis

}

virtual_ipaddress {

192.168.10.100 ######VIP

}

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

}

2.在sLave上创建配置文件

bash> vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

vrrp_script chk_redis {

script "/etc/keepalived/scripts/redis_check.sh" ###监控脚本

interval 2 ###监控时间

}

#网卡需要注意，使用ifconfig查看一下当前活动网卡

vrrp_instance VI_1 {

state BACKUP ###设置为 BACKUP

interface eth1 ###监控网卡

virtual_router_id 51

priority 10 ###权重值

nopreempt ###不抢占VIP

authentication {

auth_type PASS ###加密

auth_pass 1111 ###密码

}

track_script {

chk_redis ###执行上面定义的chk_redis

}

virtual_ipaddress {

192.168.10.100 ######VIP

}

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

}

#1.由于没有设置master,先启动的为master。

#2.由于没有设置master，backup通过权重值来争取master。

五：编写keepalied使用的脚本

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

因为Keepalived在转换状态时会依照状态来执行脚本：

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

当程序终止时则呼叫notify_stop

1.在Master和Slave上创建监控Redis的脚本

bash> mkdir /etc/keepalived/scripts

bash> cd /etc/keepalived/scripts/

bash> vim redis_check.sh

#!/bin/bash

ALIVE=`/usr/local/bin/redis-cli -p 6378 PING`

if [ "$ALIVE" == "PONG" ]; then

echo $ALIVE

exit 0

else

echo $ALIVE

exit 1

2.首先，在Redis Master上创建notity_master与notify_backup脚本：

bash> cd /etc/keepalived/scripts/

bash> vim redis_master.sh

#!/bin/bash

REDISCLI="/usr/local/bin/redis-cli -p 6378"

LOGFILE="/var/log/keepalived-redis-state.log"

ALIVE=`/usr/local/bin/redis-cli -h 192.168.10.53 -p 6378 PING`

echo "[master]" >> $LOGFILE

date >> $LOGFILE

echo "Being master...." >> $LOGFILE 2>&1

#判断对方是否存活

if [ "$ALIVE" == "PONG" ]; then

echo "Run SLAVEOF cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF 192.168.10.53 6378 >> $LOGFILE 2>&1

sleep 10 #如果存活则延迟10秒以后待数据同步完成后再取消同步状态，否则直接取消同步状态

echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

bash> vim redis_backup.sh

#!/bin/bash

REDISCLI="/usr/local/bin/redis-cli -p 6378"

LOGFILE="/var/log/keepalived-redis-state.log"

ALIVE=`/usr/local/bin/redis-cli -h 192.168.10.53 -p 6378 PING`

echo "[backup]" >> $LOGFILE

date >> $LOGFILE

echo "Being slave...." >> $LOGFILE 2>&1

echo "Run SLAVEOF cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF 192.168.10.53 6378 >> $LOGFILE 2>&1

3.在Redis Baskup上创建notity_master与notify_backup脚本：

bash> cd /etc/keepalived/scripts/

bash> vim redis_master.sh

#!/bin/bash

REDISCLI="/usr/local/bin/redis-cli -p 6378"

LOGFILE="/var/log/keepalived-redis-state.log"

ALIVE=`/usr/local/bin/redis-cli -h 192.168.10.52 -p 6378 PING`

echo "[master]" >> $LOGFILE

date >> $LOGFILE

echo "Being master...." >> $LOGFILE 2>&1

#判断对方是否存活

if [ "$ALIVE" == "PONG" ]; then

echo "Run SLAVEOF cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF 192.168.10.52 6378 >> $LOGFILE 2>&1

sleep 10 #如果存活则延迟10秒以后待数据同步完成后再取消同步状态，否则直接取消同步状态

echo "Run SLAVEOF NO ONE cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

bash> vim redis_backup.sh

#!/bin/bash

REDISCLI="/usr/local/bin/redis-cli -p 6378"

LOGFILE="/var/log/keepalived-redis-state.log"

echo "[backup]" >> $LOGFILE

date >> $LOGFILE

echo "Being slave...." >> $LOGFILE 2>&1

echo "Run SLAVEOF cmd ..." >> $LOGFILE

$REDISCLI SLAVEOF 192.168.10.52 6378 >> $LOGFILE 2>&1

#除了脚本内的ip，其他内容相同

4.然后在Master与Slave创建如下相同的脚本：

bash> vim redis_fault.sh

#!/bin/bash

LOGFILE=/var/log/keepalived-redis-state.log

echo "[stop]" >> $LOGFILE

date >> $LOGFILE

bash> vim redis_stop.sh

#!/bin/bash

LOGFILE=/var/log/keepalived-redis-state.log

echo "[stop]" >> $LOGFILE

date >> $LOGFILE

5.在主从服务器上面给脚本都加上可执行权限：

bash> chmod +x /etc/keepalived/scripts/*.sh

六：测试

略。。懒着写

注：

1.优先启动的redis为Master，另一个为slave。

2.可以通过redis-cli -p 6378 info |grep role查看当前redis的角色。

2.slave位只读模式。

3.当backup切换至master时有2秒的时间为只读。

4.当master挂掉时会检测是redis挂了还是别的原因，如果是别的原因则会有10秒的时间进行数据同步，这个期间redis为只读模式，否则backup会直接成为master，但是会损失数据。

参考资料：

http://abcve.com/redis-keepalived/