目前，Redis还没有一个类似于MySQL Proxy或Oracle RAC的官方HA方案。Redis作者有一个名为Redis Sentinel的计划 ，据称将会有监控，报警和自动故障转移三大功能，非常不错。但可惜的是短期内恐怕还不能开发完成。因此，如何在出现故障时自动转移是一个需要解决的问题。通过对网上一些资料的搜索，有建议采用HAProxy或Keepalived来实现的，事实上如果是做Failover而非负载均衡的话，Keepalived的效率肯定是超过HAProxy的，所以我决定采用Keepalived的方案。环境介绍：Master: 10.6.1.143Slave: 10.6.1.144Virtural IP Address (VIP): 10.6.1.200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。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。下面，是具体的实施步骤：在Master和Slave上安装Keepalived$ sudo apt-get install keepalived修改Master和Slave的/etc/hosts文件$ sudo vim /etc/hosts127.0.0.1 localhost10.6.1.143 redis10.6.1.144 redis-slave
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：$ sudo vim /etc/keepalived/keepalived.confvrrp_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 eth0 ###监控网卡 virtual_router_id 51 priority 101 ###权重值 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 { 10.6.1.200 ###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 }
然后，在Slave上创建如下配置文件：$ sudo vim /etc/keepalived/keepalived.confvrrp_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 eth0 ###监控网卡 virtual_router_id 51 priority 100 ###比MASTRE权重值低 authentication { auth_type PASS auth_pass redis ###密码与MASTRE相同 } track_script { chk_redis ###执行上面定义的chk_redis } virtual_ipaddress { 10.6.1.200 ###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 }
在Master和Slave上创建监控Redis的脚本$ sudo mkdir /etc/keepalived/scripts$ sudo vim /etc/keepalived/scripts/redis_check.sh#!/bin/bash
ALIVE=`/opt/redis/bin/redis-cli PING`if [ "$ALIVE" == "PONG" ]; then echo $ALIVE exit 0else echo $ALIVE exit 1fi
编写以下负责运作的关键脚本：notify_master /etc/keepalived/scripts/redis_master.shnotify_backup /etc/keepalived/scripts/redis_backup.shnotify_fault /etc/keepalived/scripts/redis_fault.shnotify_stop /etc/keepalived/scripts/redis_stop.sh因为Keepalived在转换状态时会依照状态来呼叫：当进入Master状态时会呼叫notify_master当进入Backup状态时会呼叫notify_backup当发现异常情况时进入Fault状态呼叫notify_fault当Keepalived程序终止时则呼叫notify_stop首先，在Redis Master上创建notity_master与notify_backup脚本：$ sudo vim /etc/keepalived/scripts/redis_master.sh#!/bin/bash
REDISCLI="/opt/redis/bin/redis-cli"LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILEdate >> $LOGFILEecho "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE$REDISCLI SLAVEOF 10.6.1.144 6379 >> $LOGFILE 2>&1sleep 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
$ sudo vim /etc/keepalived/scripts/redis_backup.sh#!/bin/bash
REDISCLI="/opt/redis/bin/redis-cli"LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $LOGFILEdate >> $LOGFILEecho "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 10.6.1.144 6379 >> $LOGFILE 2>&1
接着，在Redis Slave上创建notity_master与notify_backup脚本：$ sudo vim /etc/keepalived/scripts/redis_master.sh#!/bin/bash
REDISCLI="/opt/redis/bin/redis-cli"LOGFILE="/var/log/keepalived-redis-state.log"
echo "[master]" >> $LOGFILEdate >> $LOGFILEecho "Being master...." >> $LOGFILE 2>&1
echo "Run SLAVEOF cmd ..." >> $LOGFILE$REDISCLI SLAVEOF 10.6.1.143 6379 >> $LOGFILE 2>&1sleep 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
$ sudo vim /etc/keepalived/scripts/redis_backup.sh#!/bin/bash
REDISCLI="/opt/redis/bin/redis-cli"LOGFILE="/var/log/keepalived-redis-state.log"
echo "[backup]" >> $LOGFILEdate >> $LOGFILEecho "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 10.6.1.143 6379 >> $LOGFILE 2>&1
然后在Master与Slave创建如下相同的脚本：$ sudo vim /etc/keepalived/scripts/redis_fault.sh#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[fault]" >> $LOGFILEdate >> $LOGFILE
$ sudo vim /etc/keepalived/scripts/redis_stop.sh#!/bin/bash
LOGFILE=/var/log/keepalived-redis-state.log
echo "[stop]" >> $LOGFILEdate >> $LOGFILE
给脚本都加上可执行权限：$ sudo 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$ sudo /etc/init.d/redis start2.启动Slave上的Redis$ sudo /etc/init.d/redis start3.启动Master上的Keepalived$ sudo /etc/init.d/keepalived start4.启动Slave上的Keepalived$ sudo /etc/init.d/keepalived start5.尝试通过VIP连接Redis:$ redis-cli -h 10.6.1.200 INFO连接成功，Slave也连接上来了。role:masterslave0:10.6.1.144,6379,online6.尝试插入一些数据：$ redis-cli -h 10.6.1.200 SET Hello RedisOK从VIP读取数据$ redis-cli -h 10.6.1.200 GET Hello"Redis"从Master读取数据$ redis-cli -h 10.6.1.143 GET Hello"Redis"从Slave读取数据$ redis-cli -h 10.6.1.144 GET Hello"Redis"下面，模拟故障产生：将Master上的Redis进程杀死：$ sudo killall -9 redis-server查看Master上的Keepalived日志$ tailf /var/log/keepalived-redis-state.log[fault]Thu Sep 27 08:29:01 CST 2012同时Slave上的日志显示：$ tailf /var/log/keepalived-redis-state.log[master]Fri Sep 28 14:14:09 CST 2012Being master....Run SLAVEOF cmd ...OKRun 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 10.6.1.200 INFO$ redis-cli -h 10.6.1.144 INFOrole:master然后我们恢复Master的Redis进程$ sudo /etc/init.d/redis start查看Master上的Keepalived日志$ tailf /var/log/keepalived-redis-state.log[master]Thu Sep 27 08:31:33 CST 2012Being master....Run SLAVEOF cmd ...OKRun SLAVEOF NO ONE cmd ...OK同时Slave上的日志显示：$ tailf /var/log/keepalived-redis-state.log[backup]Fri Sep 28 14:16:37 CST 2012Being slave....Run SLAVEOF cmd ...OK可以发现目前的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。转载
时间： 2024-08-03 00:58:21