Redis主从配置及通过Keepalived实现Redis自动切换高可用
原文:Redis主从配置及通过Keepalived实现Redis自动切换高可用
一：环境介绍：
Master: 192.168.1.4
Slave: 192.168.1.5
Virtural IP Address (VIP): 192.168.1.253
二：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。
需要注意的是，这样做需要在Master与Slave上都开启本地化策略，否则在互相自动切换的过程中，未开启本地化的一方会将另一方的数据清空，造成数据完全丢失。
三：安装配置前准备工作
1.在主服务器192.168.1.4上面做下面操作
echo "192.168.1.4 test01" >> /etc/hosts
echo "192.168.1.5 test" >> /etc/hosts
2.在从服务器192.168.1.5上面做下面操作
echo "192.168.1.4 test01" >> /etc/hosts
echo "192.168.1.5 test" >> /etc/hosts
四：主服务器配置redis
1.下载安装redis软件包
wget http://download.redis.io/releases/redis-2.8.12.tar.gztar xf redis-2.8.12.tar.gz
cd redis-2.8.12
make && make install
cd src/
cp redis-server redis-cli redis-benchmark redis-check-aof redis-check-dump /usr/local/bin
cd /usr/local/bin
ls -ll
然后将源码中的 redis.conf 复制到 /etc/redis.conf
cp /root/redis-2.8.12/redis.conf /etc/redis.conf
修改 /etc/redis.conf里面可以把 daemonize no 修改为daemonize yes
就可以默认在后台执行redis-server了。
再制作一个 init.d 的启动脚本：
vim /etc/init.d/redis-server
#!/usr/bin/env bash
#
# redis start up the redis server daemon
#
# chkconfig: 345 99 99
# description: redis service in /etc/init.d/redis \
# chkconfig --add redis or chkconfig --list redis \
# service redis start or service redis stop
# processname: redis-server
# config: /etc/redis.conf
PATH=/usr/local/bin:/sbin:/usr/bin:/bin
REDISPORT=6379
EXEC=/usr/local/bin/redis-server
REDIS_CLI=/usr/local/bin/redis-cli
PIDFILE=/var/run/redis.pid
CONF="/etc/redis.conf"
#make sure some dir exist
if [ ! -d /var/lib/redis ] ;then
mkdir -p /var/lib/redis
mkdir -p /var/log/redis
fi
case "$1" in
status)
ps -A|grep redis
;;
start)
if [ -f $PIDFILE ]
then
echo "$PIDFILE exists, process is already running or crashed"
else
echo "Starting Redis server..."
$EXEC $CONF
fi
if [ "$?"="0" ]
then
echo "Redis is running..."
fi
;;
stop)
if [ ! -f $PIDFILE ]
then
echo "$PIDFILE does not exist, process is not running"
else
PID=$(cat $PIDFILE)
echo "Stopping ..."
$REDIS_CLI -p $REDISPORT SHUTDOWN
while [ -x ${PIDFILE} ]
do
echo "Waiting for Redis to shutdown ..."
sleep 1
done
echo "Redis stopped"
fi
;;
restart|force-reload)
${0} stop
${0} start
;;
*)
echo "Usage: /etc/init.d/redis {start|stop|restart|force-reload}" >&2
exit 1
esac
chmod o+x /etc/init.d/redis-server
chkconfig --add redis-server
service redis-server start
--------------------------------------分割线 --------------------------------------
Ubuntu 14.04下Redis安装及简单测试 http://www.linuxidc.com/Linux/2014-05/101544.htm
Redis集群明细文档 http://www.linuxidc.com/Linux/2013-09/90118.htm
Ubuntu 12.10下安装Redis（图文详解）+ Jedis连接Redis http://www.linuxidc.com/Linux/2013-06/85816.htm
Redis系列-安装部署维护篇 http://www.linuxidc.com/Linux/2012-12/75627.htm
CentOS 6.3安装Redis http://www.linuxidc.com/Linux/2012-12/75314.htm
Redis配置文件redis.conf 详解 http://www.linuxidc.com/Linux/2013-11/92524.htm
CentOS 6.3下Haproxy+Keepalived+Apache配置笔记 http://www.linuxidc.com/Linux/2013-06/85598.htm
Haproxy + KeepAlived 实现WEB群集 on CentOS 6 http://www.linuxidc.com/Linux/2012-03/55672.htm
Keepalived+Haproxy配置高可用负载均衡 http://www.linuxidc.com/Linux/2012-03/56748.htm
Haproxy+Keepalived构建高可用负载均衡 http://www.linuxidc.com/Linux/2012-03/55880.htm
--------------------------------------分割线 --------------------------------------
五：从发服务器配置redis
从服务器，配置一样，只不过 修改/etc/redis.conf 中
slaveof
slaveof 192.168.1.4 6379
然后开启从服务器的redis服务。
start redis-server start
六：进行redis主从测试
#主服务器
redis-cli -p 6379 set hello world
#从服务器
redis-cli -p 6379 get hello
"world"
#主服务器
redis-cli -p 6379 set hello world2
#从服务器
redis-cli -p 6379 get hello
"world2"
redis-cli -p 6379 set hello world
(error) READONLY You can't write against a read only slave.
成功配置主从redis服务器，由于配置中有一条从服务器是只读的，所以从服务器没法设置数据，只可以读取数据。
七：安装和配置keepalived
1.在Master和Slave上安装Keepalived
$ yum install keepalived -y
2.配置文件
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
! 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
}
vrrp_instance VI_1 {
state MASTER ###设置为MASTER
interface eth1 ###监控网卡
virtual_router_id 51
priority 100 ###权重值
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 {
192.168.1.253 ######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
}
3.然后，在Slave上创建如下配置文件：
$ 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
}
vrrp_instance VI_1 {
state BACKUP ###设置为BACKUP
interface eth1 ###监控网卡
virtual_router_id 51
priority 10 ###比MASTRE权重值低
authentication {
auth_type PASS
auth_pass 1111 ###密码与MASTRE相同
}
track_script {
chk_redis ###执行上面定义的chk_redis
}
virtual_ipaddress {
192.168.1.253 ####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
}
4.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
5.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_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
1)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 "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.1.5 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
$ vim /etc/keepalived/scripts/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 192.168.1.5 6379 >> $LOGFILE 2>&1
2)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 "[master]" >> $LOGFILE
date >> $LOGFILE
echo "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE
$REDISCLI SLAVEOF 192.168.1.4 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
$ vim /etc/keepalived/scripts/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 192.168.1.4 6379 >> $LOGFILE 2>&1
3)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 "[fault]" >> $LOGFILE
date >> $LOGFILE
$ vim /etc/keepalived/scripts/redis_stop.sh
#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[stop]" >> $LOGFILE
date >> $LOGFILE
6.在主从服务器上面给脚本都加上可执行权限：
$ chmod +x /etc/keepalived/scripts/*.sh
7.进行相关功能测试
启动Master和slave上的Redis
$ /etc/init.d/redis start
启动Master和slave上的Keepalived
$ /etc/init.d/keepalived start
尝试通过VIP连接Redis:
$ redis-cli -h 192.168.0.253 INFO
连接成功，Slave也连接上来了。
role:master
slave0:192.168.1.5,6379,online
尝试插入一些数据：
$ redis-cli -h 192.168.0.253 SET Hello Redis
OK
从VIP读取数据
$ redis-cli -h 192.168.0.253 GET Hello
"Redis"
从Master读取数据
$ redis-cli -h 192.168.0.1 GET Hello
"Redis"
从Slave读取数据
$ redis-cli -h 192.168.0.2 GET Hello
"Redis"
8.通过模拟相关故障，进行功能测试
将Master上的Redis进程杀死：
$ killall -9 redis-server
查看Master上的Keepalived日志
$ tail -f /var/log/keepalived-redis-state.log
[fault]
Thu Sep 27 08:29:01 CST 2012
同时Slave上的日志显示：
$ tail -f /var/log/keepalived-redis-state.log
[master]
2014年 07月 07日 星期一 16:42:52 CST
Being master....
Run SLAVEOF cmd ...
OK Already connected to specified master
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 192.168.1.253 INFO
$ redis-cli -h 192.168.1.5 INFO
role:master
然后我们恢复Master的Redis进程
$ /etc/init.d/redis start
查看Master上的Keepalived日志
$ tail -f /var/log/keepalived-redis-state.log
[master]
2014年 07月 07日 星期一 16:48:08 CST
Being master....
Run SLAVEOF cmd ...
OK
Run SLAVEOF NO ONE cmd ...
OK
同时Slave上的日志显示：
$ tail -f /var/log/keepalived-redis-state.log
[backup]
Fri Sep 28 14:16:37 CST 2012
Being slave....
Run SLAVEOF cmd ...
OK
发现目前的Master已经再次恢复了Master的角色，故障切换以及自动恢复都成功了。
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