linux下keepalived+redis配置双机热备方案

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

以下Master表示192.168.1.218这台主机，Slave表示192.168.1.219这台主机；master/slave表示keepalived/redis的role。 

设计思路：

通过keepalived的自定义脚本功能监控本机的redis服务状态，当监控脚本检测到redis服务出现异常时，则将本机的keepalived关闭，同时这会导致master/backup角色的变化，而keepalived在角色变化时也会触发一些机制执行相关脚本，这就为我们改变redis的master/slave状态提供了机会，这样做的目的是为了是redis的master/slave的数据保持一致。

在keepalived+redis的使用过程中有四种情况：

• 一种是keepalived挂了，同时redis也挂了，这样的话直接VIP飘走之后，是不需要进行redis数据同步的，因为redis挂了，你也无法去master上同步，不过会损失已经写在master上却还没同步到slave上面的这部分数据。
• 另一种是keepalived挂了，redis没挂，这时候VIP飘走后，redis的master/slave还是老的对应关系，如果不变化的话会把数据写入redis slave中，从而不会同步到master上去，这就要借助监控脚本反转redis的master/slave关系。这时候就要预留一点时间进行数据同步，然后反转master/slave。
• 还有一种是keepalived没挂，redis挂了，这时候根据监控脚本会检测到redis挂了，将本地的keepalived关闭，将虚拟IP漂移到另外一台服务器上。由另外一台备机承接redis业务。
• 最后一种是keepalived没挂，redis也没挂，什么都不用操作。

本文的实验环境四种情况都适合，第一种是不需要同步数据的，脚本会默认去同步数据，但是其实是不会成功的。脚本主要是用来处理第二和第三种情况的。

安装好的环境

keepalived

redis 

redis配置

#创建redis主目录
mkdir -p /usr/local/redis/{conf,logs}
 
#将可执行文件拷贝到相应的目录，注意分号别忘记
find src/ \( -perm -0001 \) -type f -exec cp -a -R -p {} /usr/local/redis/bin \;
 
#创建redis启动脚本
vi /usr/local/redis/redis-start.sh
 
####以下是master上的配置，slave上的配置只需修改对应的IP地址。
#!/bin/bash
RPATH=/usr/local/redis
KPATH=/usr/local/keepalived
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP=192.168.1.218     #这里是master的ip，如果是slave服务器上对应slave的ip
REMOTEIP=192.168.1.219   #这里是slave的ip，如果是在slave服务器上对应master的ip
 
$RPATH/bin/redis-server $RPATH/conf/redis.conf
if [ “$?” == “0” ];then
echo “[INFO]`date +%F/%H:%M:%S` :$LOCALIP redis start successful.” >> $LOGFILE
else
echo “[ERROR]`date +%F/%H:%M:%S` :$LOCALIP redis start error.” >> $LOGFILE
fi
 
#创建redis关闭脚本
vi /usr/local/redis/redis-stop.sh
 
####以下为master上的配置，slave上的配置只需修改对应的IP地址。
#!/bin/bash
RPATH=/usr/local/redis
KPATH=/usr/local/keepalived
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP=192.168.1.218    #根据实际配置，当前ip
REMOTEIP=192.168.1.219    #master就是slave的ip，slave是master的ip，反着来的
kill -9 `ps -ef|grep '/bin/redis-server'|grep -v grep|awk' {print $2}' `
if ["$?" == "0"];then
echo  "[INFO]`date +%F/%H:%M:%S` :$LOCALIP redis shutdown completed!">> $LOGFILE
else
echo "[INFO]`date +%F/%H:%M:%S` :$LOCALIP redis is not started." >> $LOGFILE
fi
 
#创建redis配置文件
cp -a -R -p redis.conf /usr/local/redis/conf/redis.conf
 
#修改redis.conf对应配置项：
vi /usr/local/redis/conf/redis.conf
 
#以下为改动部分，其他的按照实际生产环境进行调整
daemonize yes
pidfile /usr/local/redis/redis.pid
#bind 192.168.1.218    #暂时注释，方便测试
timeout 30
loglevel verbose       #实际生产环境可用notice，此处是为了详细查看各种输出细节
logfile "/usr/local/redis/logs/redis.log"
dir /usr/local/redis/
appendonly yes
 
#修改redis的属主和权限
chmod -R 750 /usr/local/redis/

配置keepalived

cd /usr/local/keepalived
 
#将keepalived.conf备份然后删掉：
mv    /usr/local/keepalived/etc/keepalived/keepalived.conf /usr/local/keepalived/etc/keepalived/keepalived.conf-bak
 
#在Master:192.168.1.218上创建如下配置文件（可根据实际情况调整）：
vi /usr/local/keepalived/etc/keepalived/keepalived.conf

! Configuration File for keepalived
vrrp_script chk_redis {
    script “/usr/local/keepalived/etc/keepalived/scripts/redis_check.sh”
    #如果脚本执行结果非0，并且weight配置的值小于0，则优先级相应的减少;如果脚本执行结果为0，并且weight配置的值大于0，则优先级相应的增加;其他情况，维持原本prority的优先级。
    #weight -20
    interval 10                 #设置脚本执行的频率。10秒一次
}
vrrp_instance VI_1 {
    state MASTER    #主服务器设置成MASTER,SLAVE设置成BACKUP
    interface eth0    #根据服务器网卡来设置，必须和服务器网卡一致，不然配置失败
    virtual_router_id 51
    priority 100      #master的这个值必须比slave高
    #设置不抢占。在priority值比较高的服务器上设置即可。priority值比较低的服务器启动时，发现值高的服务器为master，自动不抢占。
    nopreempt
    #advert_int的作用是巡检的次数。keepalived默认是在启动完成后3秒向state：MASTER切换。若此处设置成2，则是2*3=6秒后才开启切换。
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass redis   #redis密码，没有不管
    }
    virtual_ipaddress {
        192.168.1.220    #vip
    }
    track_script {
        chk_redis
    }
    notify_master /usr/local/keepalived/etc/keepalived/scripts/master.sh
    notify_backup /usr/local/keepalived/etc/keepalived/scripts/backup.sh
    notify_fault  /usr/local/keepalived/etc/keepalived/scripts/fault.sh
    notify_stop   /usr/local/keepalived/etc/keepalived/scripts/stop.sh
}
 
#在Slave:192.168.1.219上创建如下配置文件（可根据实际情况调整）：
vi /usr/local/keepalived/etc/keepalived/keepalived.conf

! Configuration File for keepalived

vrrp_script chk_redis {
    script “/usr/local/keepalived/etc/keepalived/scripts/redis_check.sh”
    #如果脚本执行结果非0，并且weight配置的值小于0，则优先级相应的减少;如果脚本执行结果为0，并且weight配置的值大于0，则优先级相应的增加;其他情况，维持原本prority的优先级。
    #weight -20
    interval 10    #设置脚本执行的频率。10秒一次
}
 
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    garp_master_delay 10
    virtual_router_id 51
    priority 90
    #nopreempt
    #advert_int的作用是巡检的次数。keepalived默认是在启动完成后3秒向state：MASTER切换。若此处设置成2，则是2*3=6秒后才开启切换。
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass redis
    }
    virtual_ipaddress {
        192.168.1.220
    }
    track_script {
        chk_redis
    }
    #当keepalived切换成master时，会触发执行master.sh
    notify_master /usr/local/keepalived/etc/keepalived/scripts/master.sh
    #当keepalived切换成slave时，会触发执行slave.sh
    notify_backup /usr/local/keepalived/etc/keepalived/scripts/backup.sh
    #当keepalived出错时，会触发执行fault.sh
    notify_fault  /usr/local/keepalived/etc/keepalived/scripts/fault.sh
    #当keepalived停止时，会触发执行stop.sh
    notify_stop   /usr/local/keepalived/etc/keepalived/scripts/stop.sh
}
 
#指定keepalived的日志文件（我没有配置成功）
vi /usr/local/keepalived/etc/sysconfig/keepalived
 
#KEEPALIVED_OPTIONS=”-D”
KEEPALIVED_OPTIONS=”-D -d -S 0″
#redhat6.0以下服务器修改/etc/syslog.conf,redhat6.0以上（包括6.0）服务器修改/etc/rsyslog.conf,新增以下内容：
#Save keepalived message to keepalived.log
local0.*  /usr/local/keepalived/logs/keepalived.log
 
#重启日志服务
service rsyslog restart
 
#将文件拷贝到相应的位置,必须在keepalived目录下，这一步能复制配置文件，生成启动服务
cp -r * /
 
#在Master和Slave上创建监控Redis的相关脚本脚本，以下脚本都是master上的配置，slave上只需修改相应的IP地址。
 
#创建文件夹
mkdir /usr/local/keepalived/etc/keepalived/scripts
mkdir /usr/local/keepalived/logs
 
#创建redis_check.sh文件========================================================
vi /usr/local/keepalived/etc/keepalived/scripts/redis_check.sh
 
内容：
#!/bin/bash
KPATH=/usr/local/keepalived
RPATH=/usr/local/redis
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP=”192.168.1.218″
REMOTEIP=”192.168.1.219″
PORT=”6379″
PID=$$
 
ALIVE=`$REDISCLI PING`
if ["$ALIVE" == "PONG"]; then
echo "[INFO]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP local redis is health.">> $LOGFILE
exit 0
else
echo "[ERROR]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP local redis is not health.">> $LOGFILE
#当发现本地redis无法连接时，等待一秒后再进行一次检查。若恢复，则提示；若仍无法连接，则关闭本地keepalived,将虚拟ip漂移到另外一台服务器上。
sleep 1
ALIVE1=`$REDISCLI PING`
if [ "$ALIVE1" == "PONG"];then
echo "[NOTICE]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP local redis become health.">> $LOGFILE
exit 0
else
echo "[ERROR]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP local redis is error.">> $LOGFILE
echo "[ERROR]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP shutdown local keepalived.">> $LOGFILE
/etc/init.d/keepalived stop
if ["$?" != "0"];then
echo "[ERROR]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP keepalived shutdown error.">> $LOGFILE
else
echo "[INFO]`date +'%Y-%m-%d:%H:%M:%S'` :$LOCALIP keepalived shutdown completed.">> $LOGFILE
 fi
exit 1
  fi
fi
 
创建master.sh文件======================================================
vi /usr/local/keepalived/etc/keepalived/scripts/master.sh
 
内容：
#!/bin/bash
KPATH=/usr/local/keepalived
RPATH=/usr/local/redis
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP="192.168.1.218"
REMOTEIP="192.168.1.219"
PORT="6379"
PID=$$
 
#当此服务器的keepalived恢复成master时，即虚拟IP切换到本机时，将本机的redis切换成role:master
echo "[WARM]———–keepalived change to master,change local redis to master—————">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave]">> $LOGFILE
#先切换成role:slave
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] Run 'SLAVEOF $REMOTEIP $PORT'">> $LOGFILE
$REDISCLI SLAVEOF $REMOTEIP $PORT >> $LOGFILE 2>&1
#同步数据
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] wait 10 sec for data sync from old master">> $LOGFILE
sleep 10
#等待10秒（此时间要根据实际业务需要进行调整），待数据同步完，再切换成role：master
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] data rsync from old mater ok…">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] Run slaveof no one,close master/slave">> $LOGFILE
$REDISCLI SLAVEOF NO ONE >> $LOGFILE 2>&1
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] wait other slave connect….">> $LOGFILE
echo "————————————-complete!——————————————">> $LOGFILE
 
#创建backup.sh文件=====================================================
vi /usr/local/keepalived/etc/keepalived/scripts/backup.sh
 
内容：
#!/bin/bash
KPATH=/usr/local/keepalived
RPATH=/usr/local/redis
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP="192.168.1.218"
REMOTEIP="192.168.1.219"
PORT="6379"
PID=$$
 
#当此服务器的keepalived恢复成slave时，即虚拟IP切换到其他服务器时，将本机redis切换成role:slave
echo "[WARM]————keepalived change to slave,change local redis to slave—————-">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master]">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] Being slave state…">> $LOGFILE 2>&1
#切换时，等待10秒，让对方同步数据（此时间要根据实际业务需要进行调整）
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] wait 10 sec for data sync from old master">> $LOGFILE
sleep 10
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] data rsync from old mater ok…">> $LOGFILE
#等数据同步完，再切换成role：slave
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] Run 'SLAVEOF  $REMOTEIP $PORT'">> $LOGFILE
$REDISCLI SLAVEOF $REMOTEIP $PORT >> $LOGFILE  2>&1
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] slave connect to $REMOTEIP $PORT ok…">> $LOGFILE
echo "————————————-complete!——————————————">> $LOGFILE
 
#创建stop.sh文件==================================================
vi /usr/local/keepalived/etc/keepalived/scripts/stop.sh
 
内容：
#!/bin/sh
KPATH=/usr/local/keepalived
RPATH=/usr/local/redis
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP="192.168.1.218"
REMOTEIP="192.168.1.219"
PORT="6379"
PID=$$
 
#当主服务器的keepalived停止时，将本机redis切换成role:slave
echo "[ERROR]—————–keepalived stop,change local redis to slave———————">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master]">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] Being slave state…">> $LOGFILE 2>&1
#切换时，等待10秒，让对方同步数据（此时间要根据实际业务需要进行调整）
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] wait 10 sec for data sync from old master">> $LOGFILE
sleep 10
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] data rsync from old mater ok…">> $LOGFILE
#等数据同步完，再切换成role：slave
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] Run 'SLAVEOF  $REMOTEIP $PORT'">> $LOGFILE
$REDISCLI SLAVEOF $REMOTEIP $PORT >> $LOGFILE  2>&1
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] slave connect to $REMOTEIP $PORT ok…">> $LOGFILE
echo "————————————-complete!——————————————">> $LOGFILE
 
#创建fault.sh文件===================================================
vi /usr/local/keepalived/etc/keepalived/scripts/fault.sh
 
内容：
#!/bin/bash
KPATH=/usr/local/keepalived
RPATH=/usr/local/redis
REDISCLI=$RPATH/bin/redis-cli
LOGFILE=$KPATH/logs/redis-state.log
LOCALIP="192.168.1.218"
REMOTEIP="192.168.1.219"
PORT="6379"
PID=$$
 
#当此服务器的keepalived出错时，将本机redis切换成role:slave
echo "[ERROR]—————keepalived is fault,change local redis to slave——————-">> $LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master]">>$LOGFILE
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] Being slave state…">> $LOGFILE 2>&1
#切换时，等待10秒，让对方同步数据（此时间要根据实际业务需要进行调整）
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] wait 10 sec for data sync from old master” >> $LOGFILE
sleep 10
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[master] data rsync from old mater ok…">> $LOGFILE
#等数据同步完，再切换成role：slave
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] Run 'SLAVEOF  $REMOTEIP $PORT'">> $LOGFILE
$REDISCLI SLAVEOF $REMOTEIP $PORT >> $LOGFILE  2>&1
echo "`date +'%Y-%m-%d:%H:%M:%S'`|$PID|state:[slave] slave connect to $REMOTEIP $PORT ok…">> $LOGFILE
echo "————————————-complete!——————————————">> $LOGFILE
 
修改监控脚本的权限:
chmod -R 750 /usr/local/keepalived/etc/keepalived/scripts/
 
系统测试
注意：
(1).在keepalived.conf配置文件中，将keepalived双机 都设置成BACKUP.同时在218上设置了nopreempt，即恢复时不抢占。而规划中是将218作为master。所以在启动过程中要遵循以下顺序：先启动218上的keepalived，等待数据同步完成后，再启动219上的keepalived.

(2).在keepalived的巡检脚本redis_check.sh中加入了状态切换的监控脚本。在master.sh中设置了当keepalived切换成master，会先将redis切换成slave进行同步数据，再切换回master。所以在启动keepalived之前，要保证Master和Slave上redis的数据是一致的，这样先启动redis的master那台的keepalived，虽然redis master会连接到redis slave同步数据，但是两边数据在刚开始的时候是一致的，并不会产生什么问题。

(3).在实际生产环境中需要修改防火墙策略，开放相应的端口。在此直接先将防火墙关闭:service iptables stop。

以下为各种测试场景和输出结果：

—————————————–初始环境————————————————–

设定一下初始环境：
—-启动218和219的redis: /usr/local/redis/redis-start.sh

—-启动218的keepalived: service keepalived start;先不启动219的keepalived.
在218上执行tail –f /usr/local/keepalived/logs/keepalived.log，可看到keepavlived切换成master state(配置文件中是设置state:backup),且绑定了VIP。 

查看218Master:redis的日志，可以看到redis切换的过程如下：

—-启动219Slave的keepalived，并查看redis的日志，可以看到redis的状态变成了slave:

—————————————–初始环境————————————————–

—————————————–设计思路3————————————————-

—-模拟设计思路3，将218Master的redis进程kill掉:

此时218的keepalived会被停止，如下图：

219的keepalived会正确切换成State:Master,VIP完成漂移，如下图：

218的redis监控日志如下:

219的redis监控日志如下，显示了219已切换成master，保证了业务（当然此处218在内存中未写入文件的数据会丢失）：

—-模拟218从故障中恢复：

因为在发现故障时，会将218上的keepalived关闭，因此恢复时，需要先启动218的redis，然后再启动218的keepalived： 查看218的keepalived日志，218的keepalived直接进入state:backup,不会造成业务的来回切换：

查看218的redis日志，218的redis启动后，会切换成已存在redis服务器的备机。

综上所示，设计思路3测试成功。

—————————————–设计思路3————————————————-

—————————————–设计思路2————————————————-

—-先设置成初始环境，再模拟设计思路2，将218的keepalived进程kill掉（service keepalived stop）:

查看218的redis监控日志：

查看219的keepalivd日志，说明keepalived正常切换了：

查看219的redis监控日志，可以看到redis完成了主从切换：

—-模拟218从keepalived故障中恢复（只需要先kill所有keepalived进程后正常启动），执行service keepalived start:

查看219的keepalived的日志，可以看到keepalived的state为backup，不会造成VIP的漂移：

查看218的redis监控日志，可

查看218的redis运行日志，可以看到redis恢复为slave身份，不会造成业务切换：

综上所示，设计思路2测试成功。

相关指令

 启动redis：/usr/local/redis/redis-start.sh
 关闭redis：/usr/local/redis/redis-stop.sh
 启动keepalived：service keepalived start
 关闭keepalived：service keepalived stop

 查看进程：ps -ef|grep xxxxx

本文参照地址：http://luyx30.blog.51cto.com/1029851/1350832