Redis+Keepalived高可用方案详细分析

背景

目前，Redis集群的官方方案还处在开发测试中，未集成到稳定版中。且目前官方开发中的Redis Cluster提供的功能尚不完善（可参考官方网站或http://www.redisdoc.com/en/latest/topic/cluster-spec.html），在生产环境中不推荐使用。通过调研发现市面上要实现采用单一的IP来访问，大多采用keepalived实现redis的双机热备作为过渡方案。

环境部署

环境介绍：
Master: 192.168.1.218 redis，keepalived
Slave: 192.168.1.219 redis，keepalived
Virtural IP Address (VIP): 192.168.1.220

设计思路：

两个redis server主从备份。提供redis 服务高可用；两个keepalived 服务主从备份，提供VIP 服务的高可用。

1)每台redis server分别有主，从两个配置文件(redis_master.conf, redis_slave.conf)，通过启动脚本启动服务，启动脚本会检测这个redis集群中的其他服务器的角色，如果有master 服务存在，则以slave角色启动，否则将自己以master服务器启动；

2) keepalived 监控脚本，定时（频率：每秒一次）检测当前服务器是否获取集群VIP，如果获取集群VIP，则将本服务器上的redis服务器设置为master。同时将远端的其他redis服务器设置为slave；保证获取集群VIP的redis 服务器角色为master，其他的设置为slave。

3) keepalived 监控脚本，还会自动检测当前redis服务器是否正常，如果连续两次检测异常，则停掉本本机的keepalived服务，释放集群VIP，让去漂移到其他可以提供redis 服务的服务器上；

4)当 Master 与 Slave 均运作正常时, Master负责服务，Slave负责同步数据；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。

实施步骤：

----创建专用用户

useradd -g develop redisadmin
echo Hisun@1125|passwd --stdin redisadmin

说明：以下部署过程都是在root(或具备sudo权限的账号)账户下进行。

----安装配置redis

1.下载redis源码

wget http://download.redis.io/releases/redis-2.8.3.tar.gz

2.安装redis

tar -zxvf redis-2.8.3.tar.gz

cd redis-2.8.3

#reds的安装可以不用执行configure

make

#测试

make test

####在速度较慢的机器上执行make test可能出现下列错误，无影响

#*** [err]: Test replication partial resync: no backlog in tests/integration/replication-psync.tcl

3.配置redis

#创建redis主目录

mkdir -p /usr/local/redis-2.8.3/{bin,conf,logs}

cp -a -R -p src/redis-server /usr/local/redis-2.8.3/bin/

cp -a -R -p src/redis-cli /usr/local/redis-2.8.3/bin/

cp -a -R -p src/redis-benchmark /usr/local/redis-2.8.3/bin/

cp -a -R -p src/redis-sentinel /usr/local/redis-2.8.3/bin/

cp -a -R -p src/redis-check-dump /usr/local/redis-2.8.3/bin/

cp -a -R -p src/redis-check-aof /usr/local/redis-2.8.3/bin/

#创建redis启动脚本

vi /usr/local/redis-2.8.3/redis-start.sh

####以下为master上的配置，slave上的配置只需要修改对应的LOCALIP和REMOTEIP即可。

#!/bin/bash
REDISPATH=/usr/local/redis-2.8.3
REDISCLI=$REDISPATH/bin/redis-cli
LOGFILE=$REDISPATH/logs/redis-state.log
LOCALIP=192.168.1.218
REMOTEIP=192.168.1.219


REMOTEREDISROLE=`$REDISCLI -h $REMOTEIP info | grep "role"`
if grep "role:master" <<< $REMOTEREDISROLE ; then
        #start as slave
        $REDISPATH/bin/redis-server $REDISPATH/conf/redis_slave.confif [ "$?" == "0" ];then
                echo "[INFO]`date +%F/%H:%M:%S` :$LOCALIP start as slave successful." >> $LOGFILEelseecho "[ERROR]`date +%F/%H:%M:%S` :$LOCALIP start as slave error." >> $LOGFILE
        fi
else#start as master
        $REDISPATH/bin/redis-server $REDISPATH/conf/redis_master.confif [ "$?" == "0" ];then
                echo "[INFO]`date +%F/%H:%M:%S` :$LOCALIP start as master successful." >> $LOGFILEelseecho "[ERROR]`date +%F/%H:%M:%S` :$LOCALIP start as master error." >> $LOGFILE
        fi
fi

#创建redis关闭脚本

vi /usr/local/redis-2.8.3/redis-stop.sh

####以下为master上的配置，slave上的配置相同。

#!/bin/bash
REDISPATH=/usr/local/redis-2.8.3
LOGFILE=$REDISPATH/logs/redis-state.log
kill -9 `ps -ef|grep '/bin/redis-server'|grep -v grep|awk  '{print $2}'`
if [ "$?" == "0" ];then
        echo "[INFO]`date +%F/%H:%M:%S` :redis shutdown completed!" >> $LOGFILE
elseecho "[ERROR]`date +%F/%H:%M:%S` :redis is not started." >> $LOGFILE
fi


#创建redis配置文件

cp -a -R -p redis.conf /usr/local/redis-2.8.3/conf/redis_master.conf

cp -a -R -p redis.conf /usr/local/redis-2.8.3/conf/redis_slave.conf

#修改redis_master.conf对应配置项：

####192.168.1.218主服务器redis_master.conf对应配置项######
#daemonize no
daemonize yes
#bind 127.0.0.1
bind 192.168.1.218
logfile "/usr/local/redis-2.8.3/logs/redis.log"
#其他配置依据实际生产环境修改
########################################################
####192.168.1.219从服务器redis_master.conf对应配置项######
#daemonize no
daemonize yes
#bind 127.0.0.1
bind 192.168.1.219
logfile "/usr/local/redis-2.8.3/logs/redis.log"
#其他配置依据实际生产环境修改
########################################################

#修改redis_slave.conf对应配置项：

####192.168.1.218主服务器redis_slave.conf对应配置项#######
#daemonize no
daemonize yes
#bind 127.0.0.1
bind 192.168.1.218
logfile "/usr/local/redis-2.8.3/logs/redis.log"
# slaveof <masterip> <masterport>
slaveof 192.168.1.219 6379
#其他配置依据实际生产环境修改
########################################################
####192.168.1.219从服务器redis_slave.conf对应配置项#######
#daemonize no
daemonize yes
#bind 127.0.0.1
bind 192.168.1.219
logfile "/usr/local/redis-2.8.3/logs/redis.log"
# slaveof <masterip> <masterport>
slaveof 192.168.1.218 6379
#其他配置依据实际生产环境修改
########################################################

#修改redis的属主和权限

chmod –R 750 /usr/local/redis-2.8.3/

chown –R redisadmin:develop /usr/local/redis-2.8.3/

----安装配置keepalived

1.下载keepalived源码Release 1.2.9

注意：最新版为1.2.10测试过程中出错.
wget http://www.keepalived.org/software/keepalived-1.2.9.tar.gz
2.安装keepalived

需要安装以下依赖包： make gcc libpopt-dev libnl-dev libcurl4-openssl-dev popt openssl
cd

tar –zxvf keepalived-1.2.9.tar.gz

cd keepalived-1.2.9

./configure --prefix=/usr/local/keepalived

make && make install

3.配置keepalived

#在Master和Slave上创建如下配置文件（可根据实际情况调整）：

mv /usr/local/keepalived/etc/keepalived/keepalived.conf /usr/local/keepalived/etc/keepalived/keepalived.conf-bak
vim /usr/local/keepalived/etc/keepalived/keepalived.conf

vrrp_script chk_redis {
        script "/usr/local/keepalived/etc/keepalived/scripts/chk_redis.sh"   ###监控脚本
        interval 2                                        ###监控时间
}
vrrp_instance VI_1 {
        state MASTER                            ###设置为MASTER
        interface eth3                          ###监控网卡,依据实际情况来定  
        virtual_router_id 51
        priority 101                            ###权重值
        advert_int 1 
        authentication {
                     auth_type PASS             ###加密
                     auth_pass redis            ###密码
        }
        track_script {
                chk_redis                       ###执行上面定义的chk_redis
        }
        virtual_ipaddress {
             192.168.1.220                         ###VIP
        }
}

在Master和Slave上创建监控Redis的脚本
mkdir /usr/local/keepalived/etc/keepalived/scripts
vi /usr/local/keepalived/etc/keepalived/scripts/chk_redis.sh

####以下为master上的配置，slave上的配置只需要修改对应的LOCALIP和REMOTEIP即可。

#!/bin/bash
REDISPATH=/usr/local/redis-2.8.3
REDISCLI=$REDISPATH/bin/redis-cli
LOGFILE=$REDISPATH/logs/redis-state.log
LOCALIP=192.168.1.218
REMOTEIP=192.168.1.219
VIP=192.168.1.220

VIPALIVE=`ip a | grep "$VIP"`
if [ "$VIPALIVE" == "" ]; then
	echo "[info]:"`date`" keepalived server is pengding or stop" >> $LOGFILE
else
	echo "bbb" >> $LOGFILE
	#check local service is running
	if [ "`$REDISCLI –h $LOCALIP –p 6379 PING`" == "PONG" ]; then
		# check local redis server role.
		REDISROLE=`$REDISCLI info | grep "role"`
		if grep "role:slave" <<< $REDISROLE ; then
			#change local redis server as master 
			echo "[info1]:"`date`" Run SLAVEOF NO ONE cmd ..." >> $LOGFILE
			$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1

			#change remoting redis server as slave
			REMOTEREDISROLE=`$REDISCLI -h $REMOTEIP info | grep "role"`
			if grep "role:master" <<< $REMOTEREDISROLE ; then
				echo "[info2]:"`date`" Run remote server SLAVEOF cmd ..." >> $LOGFILE
				$REDISCLI -h $REMOTEIP SLAVEOF $LOCALIP 6379 >> $LOGFILE  2>&1
			fi
		else
			REMOTEREDISROLE=`$REDISCLI -h $REMOTEIP info | grep "role"`
			if grep "role:master" <<< $REMOTEREDISROLE ; then
				echo "[info3]:"`date`" Run remote server SLAVEOF cmd ..." >> $LOGFILE
				$REDISCLI -h $REMOTEIP SLAVEOF $LOCALIP 6379 >> $LOGFILE  2>&1
			fi
		fi	
	else
		echo "[warn]:"`date`"  redis server($LOCALIP) is not health..." >> $LOGFILE
		sleep 1
		if [ "`$REDISCLI –h $LOCALIP –p 6379 PING`" != "PONG" ]; then
			echo "[error]:"`date`"  redis server($LOCALIP) will be stop..." >> $LOGFILE
			service keepalived stop
		fi
	fi
fi

重要：将相应的配置文件放到相应的地方.

#首先在2台服务器上设置keepalived的启动文件：

cp -a -R -p /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/keepalived

chmod 750 /etc/rc.d/init.d/keepalived

chown root /etc/rc.d/init.d/keepalived
#然后在2台服务器上创建配置文件的链接：

mkdir /etc/keepalived/

ln -s /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/keepalived.conf

ln -s /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/keepalived

系统测试

注意:一定要先启动redis，再启动keealived，否则redis_check.sh会将keepalived自动关闭。

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/redis-2.8.3/redis-start.sh

#关闭时，直接杀死进程或执行以下脚本

/usr/local/redis-2.8.3/redis-stop.sh

2.启动Slave上的Redis
/usr/local/redis-2.8.3/redis-start.sh

#关闭时，直接杀死进程或执行以下脚本

#/usr/local/redis-2.8.3/redis-stop.sh

3.启动Master上的Keepalived
/etc/rc.d/init.d/keepalived start

#关闭方法

#/etc/rc.d/init.d/keepalived stop

4.启动Slave上的Keepalived
/etc/rc.d/init.d/keepalived start

#关闭方法

#/etc/rc.d/init.d/keepalived stop

-----------------------------------------------------------------------------

Centos开机自启动redis

修改redis.conf，打开后台运行选项：

# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
daemonize yes

编写脚本，vim /etc/init.d/redis:

# chkconfig: 2345 10 90
# description: Start and Stop redis

PATH=/usr/local/bin:/sbin:/usr/bin:/bin

REDISPORT=6379 #实际环境而定
EXEC=/usr/local/redis/src/redis-server #实际环境而定
REDIS_CLI=/usr/local/redis/src/redis-cli #实际环境而定

PIDFILE=/var/run/redis.pid
CONF="/usr/local/redis/redis.conf" #实际环境而定

case "$1" in
        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 exists, 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

执行权限：

chmod +x /etc/init.d/redis

开机自启动：

# 尝试启动或停止redis
service redis start
service redis stop

# 开启服务自启动
chkconfig redis on

参考资料：

http://luyx30.blog.51cto.com/1029851/1350832

http://www.cnblogs.com/davidwang456/p/3525090.html

http://patrick-tang.blogspot.com/2012/06/redis-keepalived-failover-system.html

http://deidara.blog.51cto.com/400447/302402

http://my.oschina.net/guol/blog/182491

http://shiguanghui.iteye.com/blog/2001499

http://my.oschina.net/indestiny/blog/197272

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原文地址：https://www.cnblogs.com/liubei/p/RedisK.html